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Original Articles
Adjuvant Chemotherapy in Breast Cancer After Neoadjuvant Therapy: Essential or Optional?
Di Zhang, Luo Yang, Yuan Zheng, Qi Zhou
Received December 31, 2024  Accepted April 20, 2025  Published online April 24, 2025  
DOI: https://doi.org/10.4143/crt.2024.1254    [Accepted]
AbstractAbstract PDF
Purpose
This study aimed to evaluate the impact of postoperative adjuvant chemotherapy (AC) on survival outcomes in breast cancer (BC) patients who have already undergone neoadjuvant chemotherapy (NAC) followed by surgery.
Materials and Methods
Data from a population-based cohort (2010-2020) were analyzed for BC patients treated with NAC and surgery. Univariate and multivariate Cox regression identified prognostic factors for overall survival (OS), and a nomogram was developed and validated. Personalized scores from the nomogram were used for risk stratification to assess the effect of postoperative AC.
Results
A total of 15,921 BC patients were analyzed, with 11,144 in the training cohort and 4,777 in the validation cohort. The key prognostic indicators for OS included age, race, marital status, histological grade, breast cancer subtype, T stage, N stage, type of surgery, and response to NAC (all p<0.05). The nomogram effectively predicted individualized OS rates and stratified patients into various risk categories. Postoperative AC was found to significantly enhance OS in the high-risk subgroup (p=0.011 in the training cohort, p=0.012 in the overall population). However, for the low-risk subgroup, there was no significant survival benefit from postoperative AC (p=0.130 for the training cohort, p=0.588 for the overall population), suggesting that some patients might safely forgo unnecessary postoperative AC.
Conclusion
This study efficiently differentiates between varying levels of risk, enabling clinicians to identify patients unlikely to benefit from postoperative AC and thus reduce the likelihood of overtreatment.
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Differences in Responses to Neoadjuvant Anti-HER2 Therapy between HER2 2+ISH+ and HER2 3+ in HER2-Positive Breast Cancer
Lingjun Ma, Ran Zheng, Lingyun Xu, Ying Zhu, Hong Yin, Xiaoqing Zhang, Rong Deng, Jue Wang, Xiaoming Zha
Received December 12, 2024  Accepted April 18, 2025  Published online April 21, 2025  
DOI: https://doi.org/10.4143/crt.2024.1200    [Accepted]
AbstractAbstract PDF
Purpose
Dual anti-HER2 drugs has become the standard regimen for neoadjuvant systematic treatment (NST) to HER2-positive breast cancer patients. However, the efficacy varies greatly among patients with different HER2 protein expression levels
Materials and Methods
A total of 575 HER2-positive breast cancer patients from multiple centers throughout China from 2013 to 2022 were retrospectively analyzed. We compared clinicopathological features in different HER2 IHC classes (HER2 2+ISH+ or HER2 3+), and their difference in response to NST and survival with single or dual anti-HER2 drugs. Drug sensitivity assays were used to evaluate different efficacy of anti-HER2 drugs in vitro.
Results
Compared to HER2 3+ subgroup, the HER2 2+ISH+ group had a higher proportion of HR+ status (48.7% vs. 76.1%; p < 0.001), more HER2 protein loss after NST, lower pCR rate (46.07% vs. 16.24%; p < 0.001), and tended to have worse DFS. In HER2 2+ISH+ patients, treated with pertuzumab and trastuzumab in combination had no significant improvement in pCR (19.12% vs. 12.24%; p=0.287) and DFS (p=0.908) than using alone. Drug sensitivity assay showed poor efficacy with dual anti-HER2 drugs in HER2 2+ISH+ cell lines, however, T-Dxd drugs had a satisfactory effect.
Conclusion
Owing to the differences in clinicopathological features and treatment efficacy, we considered the HER2 2+ISH+ group to be a distinct subtype and defined it as the HER2-moderate-positive (HER2-mod) subgroup. In this subgroup, dual anti-HER2 drugs did not exert significant improvement in pCR and DFS. Therefore, treatment optimization is warranted, with ADC drugs as potential options.
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The Impact of Obesity on Treatment Outcomes in Patients with Hormone Receptor-Positive HER2-Negative Metastatic Breast Cancer Receiving CDK 4/6 Inhibitors
Yoo Bin Jung, Hee Kyung Ahn, Hyun-Young Shin, Ji Hyung Hong, Chai Hong Rim
Received January 25, 2025  Accepted April 13, 2025  Published online April 15, 2025  
DOI: https://doi.org/10.4143/crt.2025.110    [Accepted]
AbstractAbstract PDF
Purpose
Guidelines from the aromatase inhibitor era for early breast cancer (EBC) treatment recommend maintaining a body mass index (BMI) below 25. In the current era of CDK 4/6 inhibitors, now standard in metastatic breast cancer (MBC), limited data exist on treatment outcomes in obese patients. This study investigates how adiposity affects the treatment outcome of CDK 4/6 inhibitors in patients with hormone receptor (HR)-positive, HER2-negative MBC.
Materials and Methods
We searched PubMed, MEDLINE, and Embase databases, assessing efficacy outcomes such as progression-free survival (PFS) based on obesity markers, including BMI and visceral adipose tissue (VAT) index.
Results
Twelve studies were reviewed, with seven studies and 1,812 patients included in a pooled meta-analysis. Among patients with BMI ≥25, modest improvement in PFS was observed, with a pooled hazard ratio (HR) of 0.944 (95% CI, 0.909-0.980; p = 0.003). Besides, add-on analysis using VAT to define obesity revealed a notable PFS improvement, with a pooled HR of 0.452 (95% CI, 0.256-0.798; p = 0.006).
Conclusion
While BMI-defined obesity showed slight PFS improvement with CDK 4/6 inhibitors and endocrine therapy, using VAT to define obesity revealed significant PFS gains. This highlights the need for further research on biomarker to clarify the role of adiposity in MBC, which may differ from its impact in EBC.
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Spatial Transcriptomic Landscape of Brain Metastases from Triple-Negative Breast Cancer: Comparison of Primary Tumor and Brain Metastases Using Spatial Analysis
Jihwan Yoo, Inho Park, Hyun Jung Kim, Hun Ho Park, Sora Lee, Jee Hung Kim, Yoon Jin Cha
Received January 8, 2025  Accepted April 13, 2025  Published online April 15, 2025  
DOI: https://doi.org/10.4143/crt.2025.033    [Accepted]
AbstractAbstract PDF
Purpose
Triple-negative breast cancer (TNBC) is a particularly aggressive subtype of breast cancer, with approximately 30% of patients eventually developing brain metastases (BM), which result in poor outcomes. An understanding of the tumor microenvironment (TME) at both primary and metastatic sites offers insights into the mechanisms underlying BM and potential therapeutic targets.
Materials and Method
Spatial RNA sequencing (spRNA-seq) was performed on primary TNBC and paired BM tissues from three patients, one of whom had previously received immune checkpoint inhibitors before BM diagnosis. Specimen regions were categorized into tumor, proximal, and distal TME based on their spatial locations. Gene expression differences across these zones were analyzed, and immune cell infiltration was estimated using TIMER. A gene module analysis was conducted to identify key gene clusters associated with BM.
Results
Distinct gene expression profiles were noted in the proximal and distal TMEs. In BM, the proximal TME exhibited neuronal gene expression, suggesting neuron-tumor interactions compared to tumor, and upregulation of epithelial genes compared to the distal TME. Immune cell analysis revealed dynamic changes in CD8+ T cells and macrophages across the tumor and TME zones. Gene module analysis identified five key modules, including one related to glycolysis, which correlated with patient survival. Drug repurposing analysis identified potential therapeutic targets, including VEGFA, RAC1, EGLN3, and CAMK1D.
Conclusion
This study provides novel insights into the transcriptional landscapes in TNBC BM using spRNA-seq, emphasizing the role of neuron-tumor interactions and immune dynamics. These findings suggest new therapeutic strategies and underscore the importance of further research.
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Comparison of Long-term Oncological Outcome of Sentinel Lymph Node Mapping Methods (Dye-Only versus Dye and Radioisotope) in Breast Cancer Patients Following Neoadjuvant Chemotherapy
Jinyoung Byeon, Changjin Lim, Eunhye Kang, Ji-Jung Jung, Hong-Kyu Kim, Han-Byoel Lee, Hyeong-Gon Moon, Wonshik Han
Received December 30, 2024  Accepted April 13, 2025  Published online April 15, 2025  
DOI: https://doi.org/10.4143/crt.2024.1253    [Accepted]
AbstractAbstract PDF
Purpose
Sentinel lymph node biopsy (SLNB) using dye and isotope (DUAL) is recommended over the dye-only (DYE) method after neoadjuvant chemotherapy (NCT) due to potentially lower false-negative rates. However, the long-term outcome of either method is unclear. We aimed to compare the long-term oncological outcomes of DYE versus DUAL SLNB methods in patients who received NCT.
Materials and Methods
In this retrospective cohort study, 893 patients who underwent SLNB following NCT and had pathologically negative lymph nodes were included. After propensity score matching for cT, cN, and pT stages, 280 patients were in the DYE group and 560 in the DUAL group. Indigo carmine was used for dye and Tc-99m antimony trisulfate for isotope mapping.
Results
Median follow-up was 75.6 months in the DYE group and 83.0 months in the DUAL group. Mean (±SD) number of harvested sentinel nodes was 6.7 (±3.4) and 6.7 (±3.8) in the DYE and DUAL groups (p=0.51). Five-year distant metastasis-free survival was 95.2% in DYE group and 93.3% in DUAL group (HR=1.45; 95% CI, 0.82–2.57; p=0.19). Disease-free survival (HR=0.97; 95% CI, 0.69–1.50; p=0.91) and overall survival (HR=0.98; 95% CI, 0.56–1.69; p=0.95) were not significantly different. Axillary recurrence rate was 1.8% and 2.5% in DYE and DUAL groups(p=0.64).
Conclusion
Long-term oncological outcomes did not significantly differ between DYE and DUAL SLNB methods. The dye-only method can be safely recommended for breast cancer patients who received NCT.
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Association Between Benign Thyroid Disorders and Breast Cancer Risk in Korean Women
Boyoung Park, Thi Xuan Mai Tran
Received August 16, 2024  Accepted February 25, 2025  Published online February 26, 2025  
DOI: https://doi.org/10.4143/crt.2024.787    [Accepted]
AbstractAbstract PDF
Purpose
This study aimed to investigate the potential association between thyroid disorders and breast cancer (BC) risk in a cohort of Korean women.
Materials and Methods
Data for this retrospective cohort study were obtained from the Korean National Health Insurance database, including all women aged ≥ 40 who underwent BC screening from 2009 to 2010 in Korea. Thyroid disorders were identified using medical records from 2009 to 2010 and extracted using the ICD-10 codes for thyroid nodules, hypothyroidism, and hyperthyroidism. BC cases were defined using the ICD-10 codes and tracked until December 2021. A Cox regression model was used to evaluate the association between thyroid disorders and the risk of BC. Additionally, we evaluated the association between well-known risk factors of BC and thyroid disorders using logistic regression analysis.
Results
Among 5,051,633 women, the mean (standard deviation) age was 55.2 (10.7) years, and the median follow-up was 11.6 years, with 87,784 BC cases recorded. The proportions of patients with thyroid nodules, hypothyroidism, and hyperthyroidism were 2.5, 1.8, and 0.9%, respectively. The hazard ratio (HR) for BC risk associated with thyroid nodules was 1.16 (95% CI 1.11–1.20), for hypothyroidism was 0.98 (95% CI 0.93–1.03), and for hyperthyroidism was 1.13 (95% CI 1.06–1.21). In both premenopausal and postmenopausal women, an increased risk of BC was significantly associated with thyroid nodules (aHR 1.16 and 1.13) and hyperthyroidism (aHR 1.11 and 1.16). History of benign breast disease, oral contraceptive use, breastfeeding, menopausal status, and hormone replacement therapy were associated with thyroid nodules and hyperthyroidism.
Conclusion
Our findings suggest an increased risk of BC in women with a history of thyroid nodules and hyperthyroidism, whereas no such association was found in women with hypothyroidism.
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Novel Breast Cancer Risk Assessment Tools for Pre- and Post-Menopausal Asian Women: Development and Validation in a Nationwide Mammographic Screening Cohort
Wonyoung Jung, Yong-Moon Mark Park, Sang Hyun Park, Kyungdo Han, Junhee Park, Yohwan Yeo, Jung Kwon Lee, Dale P. Sandler, Dong Wook Shin
Received September 4, 2024  Accepted January 30, 2025  Published online January 31, 2025  
DOI: https://doi.org/10.4143/crt.2024.861    [Accepted]
AbstractAbstract PDF
Purpose
Widely used breast cancer risk-prediction tools are based on data from Western countries, but risk factors may differ for Asian women. Hence, we aimed to develop a risk assessment tool for breast cancer in Asian women using a nationwide, population-based mammographic screening cohort.
Materials and Methods
Women aged ≥40 years who underwent breast cancer screening and general health examination in 2009 were included. Age, body mass index (BMI), breast density, lifestyle and reproductive factors, and comorbidities were used to develop 5-year breast cancer risk-prediction models for premenopausal (n=771,856) and postmenopausal (n=1,108,047) women at baseline. The best-fit risk prediction model was constructed using backward stepwise selection in a Cox proportional hazards model and was transformed into a risk score nomogram. The performance was assessed by discrimination and calibration.
Results
In premenopausal women, high BMI, low parity, short breastfeeding period, early age at menarche, high breast density, a history of benign breast masses, and family history of breast cancer contributed to the risk prediction of breast cancer. In postmenopausal women, age, diabetes mellitus, dyslipidemia, late-onset menopause, and hormone replacement therapy use were additional risk predictors of breast cancer. Our risk-prediction model showed a concordant statistic of 0.58 (0.57–0.59) for premenopausal women and 0.64 (0.63–0.65) for postmenopausal women. The calibration plot demonstrated good correlations for both models.
Conclusion
Our breast cancer risk-prediction model demonstrated performance comparable to that of Western countries, especially among postmenopausal women. This provides a foundation for implementing risk-based screening recommendations in Asian women.
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Prognostic Performance of the Next-Generation Sequencing-Based Multigene Assay in Early Breast Cancer Patients Treated According to the 21-Gene Assay Results
Eunhye Kang, Jong-Ho Cheun, Jeeyeon Lee, Jiwon Koh, Hyunwoo Lee, Ji-Young Park, Hee Jin Lee, Byeongju Kang, Woong Ki Park, Jeongeun Son, Bumjoon Kim, Woosung Chung, Wonshik Han, Han-Byoel Lee, Sae Byul Lee, Jai Min Ryu
Received October 28, 2024  Accepted December 22, 2024  Published online December 23, 2024  
DOI: https://doi.org/10.4143/crt.2024.1035    [Accepted]
AbstractAbstract PDF
Purpose
Multigene assays guide treatment decisions in early-stage hormone receptor-positive breast cancer. OncoFREE, a next-generation sequencing assay using 179 genes, was developed for this purpose. This study aimed to evaluate the concordance between the Oncotype DX (ODX) Recurrence Score (RS) and the OncoFREE Decision Index (DI) and to compare their performance.
Materials and Methods
We retrospectively collected tumor blocks from patients who underwent ODX and treatment between 2012 and 2022 at four tertiary hospitals and performed OncoFREE on these samples. Distant metastasis-free survival (DMFS) was compared using RS and DI, with score cut-offs of 25 and 20, respectively.
Results
Among 838 patients, a strong correlation was observed between RS and DI (Pearson correlation coefficient 0.83). At a median follow-up of 54 months, patients with high DI had significantly worse DMFS compared to those with low DI (log-rank p < 0.001, hazard ratio [HR] 5.73, 95% confidence interval [CI] 1.87–17.57; multivariable p=0.048, HR 3.45, 95% CI 1.01–11.76). In 513 patients aged ≤50 years, DMFS was significantly different as a function of DI (p=0.035, HR 3.98, 95% CI 1.00–15.89) but not RS (p=0.792). Among 376 patients aged ≤50 years who avoided chemotherapy based on low RS, 64 with high DI had worse DMFS (p=0.015, HR 5.91, 95% CI 1.17–29.78).
Conclusion
OncoFREE showed strong concordance with ODX and effectively identified high-risk patients, particularly in younger individuals. It could be an affordable alternative to ODX for guiding treatment in hormone receptor-positive early breast cancer.
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Evaluating the Effects of Mindfulness-Based Self-Help via an OTT Platform on Breast Cancer Patients Undergoing Radiotherapy: A Prospective Nonrandomized Controlled Trial
Hyejo Ryu, Si Nae You, Sohee Oh, Bora Kim, Jeong-Hyun Kim, In Ah Kim
Received October 1, 2024  Accepted November 20, 2024  Published online November 25, 2024  
DOI: https://doi.org/10.4143/crt.2024.955    [Epub ahead of print]
AbstractAbstract PDFSupplementary MaterialPubReaderePub
Purpose
Previous research showed the benefits of mindfulness meditation on the mental health and quality of life of breast cancer patients. Traditionally, these programs relied on in-person interactions, but the coronavirus disease 2019 pandemic necessitated alternative delivery methods. This study evaluated the effectiveness and feasibility of a mindfulness-based self-help (MBSH) program via Netflix for breast cancer patients undergoing radiotherapy.
Materials and Methods
This prospective nonrandomized controlled study assigned patients to a control or MBSH group based on age and preference. The MBSH group watched episodes of “Headspace Guide to Meditation” on Netflix and practiced guided meditation at least twice per week for four weeks. Participants completed questionnaires assessing depression, anxiety, stress, insomnia, mindfulness, mental adjustment to cancer, and quality of life at weeks 0 and 8. Data were analyzed using a two-way repeated measures ANOVA.
Results
Ninety-six patients participated, with 84 eligible for final analysis (44 control, 40 MBSH). Intention-to-treat analysis revealed a significant improvement in depression (f=4.306, p=0.041). Half of the experimental group (n=20) adhered to the study protocol. At week 8, the experimental group showed significant improvement compared to the control group in cognitive avoidance (f=8.530, p=0.005) and positive attitude (f=5.585, p=0.021), both indicative of adaptive coping strategies.
Conclusion
This study firstly investigated the effect and feasibility of a Netflix-based MBSH program for breast cancer patients undergoing radiotherapy. Findings suggest MBSH on Netflix can improve mental health and adaptive mental adjustment, highlighting the potential of self-help mindfulness interventions to enhance the well-being of cancer patients and need for further research.
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Estimation of Population Attributable Fraction by Hormone and Reproductive Factors on Female Cancer in the Republic of Korea, 2015 to 2030
Youjin Hong, Soseul Sung, Woojin Lim, Sungji Moon, Kwang-Pil Ko, Jung Eun Lee, Inah Kim, Sun Ha Jee, Sun-Seog Kweon, Min-Ho Shin, Sangmin Park, Seung-Ho Ryu, Sun Young Yang, Jeongseon Kim, Sang-Wook Yi, Yoon-Jung Choi, Jeong-Soo Im, Hong Gwan Seo, Sue K. Park
Received July 26, 2024  Accepted November 18, 2024  Published online November 19, 2024  
DOI: https://doi.org/10.4143/crt.2024.707    [Epub ahead of print]
AbstractAbstract PDFSupplementary MaterialPubReaderePub
Purpose
Population attributable fractions (PAFs) for hormone and reproductive factors have been estimated in several countries. International Agency for Research on Cancer (IARC) designated as group 1 and group 2A carcinogen for hormone factors in breast, ovarian, endometrial and uterine cervix cancer. This study aimed to estimate the PAFs of hormone/reproductive factor attributed to cancer incidence and deaths in Korean women and projected trends from 2015 to 2030.
Materials and Methods
The PAF was estimated with using the 2005 standardized prevalence rates and 2020 incidence and deaths with a 15-year latency. Based on the Levin’s formula, prevalence rates were calculated using the Korea National Health and Nutrition Examination Survey (KNHANES) and the relative risks, which were the risk of selected female cancer associated with oral contraceptive, hormone replacement therapy and duration of breastfeeding, were estimated from the meta-analysis of studies performed in Korean women population. Studies based on the Asian and Global populations were calculated as a sensitivity analysis.
Results
The estimation PAFs for hormone was 1.02% with 1,192 cases and reproductive was 2.67% with 3,112 cases. Moreover, 0.40% (125 deaths) and 1.09% (342 deaths) in female-related cancer deaths in order. Estrogen-progesterone combined hormone replacement therapy (HRT) accounted the most proportion in hormone factors and breastfeeding in reproductive factors. Also, the breast cancer had the highest percent in both hormone and reproductive factors.
Conclusion
Through this study, 1.02% and 2.67% of female-related cancer incidence will be reduced by encouraging avoiding the use of oral contraceptives and HRT and breastfeeding for more than 6 months in reproductive factors. Additionally, among four selected female cancers in this study, breast cancer was observed to be a significant level of prevention.
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Breast cancer
Kinect-Based Mixed Reality Exercise Program Improves Physical Function and Quality of Life in Breast Cancer Survivors: A Randomized Clinical Trial
Byunggul Lim, Xinxing Li, Yunho Sung, Parivash Jamrasi, SoYoung Ahn, Hyejung Shin, Wook Song
Cancer Res Treat. 2025;57(2):478-491.   Published online October 30, 2024
DOI: https://doi.org/10.4143/crt.2024.758
AbstractAbstract PDFPubReaderePub
Purpose
Exercise is an effective non-pharmacological approach for alleviating treatment-related adverse effects and enhancing physical fitness in breast cancer survivors. A Kinect-based mixed reality device (KMR), with real-time feedback and user data collection, is an innovative exercise intervention for breast cancer survivors. This study aimed to investigate the effect of KMR exercise program on quality of life (QOL) and physical function in breast cancer survivors.
Materials and Methods
Seventy-seven participants were randomly assigned to either the KMR exercise group or home stretching group with an 8-week intervention. Physical function (shoulder range of motion, body composition, aerobic capacity, and hand grip strength) was evaluated before and after the intervention period. Participants completed questionnaires such as the Disabilities of the Arm, Shoulder, and Hand (DASH), Functional Assessment of Cancer Therapy-Breast, and International Physical Activity Questionnaire (IPAQ) to assess upper extremity disabilities, QOL, and physical activity levels.
Results
Significant group-by-time interaction was found for flexion of the operated arm (154.3±12.5 to 165.8±11.2), and the non-operated arm (158.2±13.8 to 166.5±12.2), abduction of the non-operated arm (154.8±31.6 to 161.1±28.1), and adduction of the operated arm (46.5±9.1 to 52.6±7.2). Significant improvements were also observed in DASH (46.8±9.1 to 40.8±9.3) and IPAQ (1,136.3±612.8 to 1,287±664.1).
Conclusion
The KMR exercise program effectively improved the physical function, alleviated edema, reduced upper extremity disability, and enhanced the QOL in breast cancer survivors. Coupled with significant group-by-time interactions for various outcomes, the results emphasize the potential benefits of incorporating the KMR exercise program to improve the QOL in breast cancer survivors.
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Synergistic Activation of LEPR and ADRB2 Induced by Leptin Enhances Reactive Oxygen Specie Generation in Triple-Negative Breast Cancer Cells
Chang Liu, Jing Yu, Yongjun Du, Yu Xie, Xiaofei Song, Chang Liu, Yan Yan, Yue Wang, Junfang Qin
Cancer Res Treat. 2025;57(2):457-477.   Published online August 21, 2024
DOI: https://doi.org/10.4143/crt.2024.368
AbstractAbstract PDFSupplementary MaterialPubReaderePub
Purpose
Leptin interacts not only with leptin receptor (LEPR) but also engages with other receptors. While the pro-oncogenic effects of the adrenergic receptor β2 (ADRB2) are well-established, the role of leptin in activating ADRB2 in triple-negative breast cancer (TNBC) remains unclear.
Materials and Methods
The pro-carcinogenic effects of LEPR were investigated using murine TNBC cell lines, 4T1 and EMT6, and a tumor-bearing mouse model. Expression levels of LEPR, NADPH oxidase 4 (NOX4), and ADRB2 in TNBC cells and tumor tissues were analyzed via western blot and quantitative real-time polymerase chain reaction. Changes in reactive oxygen species (ROS) levels were assessed using flow cytometry and MitoSox staining, while immunofluorescence double-staining confirmed the co-localization of LEPR and ADRB2.
Results
LEPR activation promoted NOX4-derived ROS and mitochondrial ROS production, facilitating TNBC cell proliferation and migration, effects which were mitigated by the LEPR inhibitor Allo-aca. Co-expression of LEPR and ADRB2 was observed on cell membranes, and bioinformatics data revealed a positive correlation between the two receptors. Leptin activated both LEPR and ADRB2, enhancing intracellular ROS generation and promoting tumor progression, which was effectively countered by a specific ADRB2 inhibitor ICI118551. In vivo, leptin injection accelerated tumor growth and lung metastases without affecting appetite, while treatments with Allo-aca or ICI118551 mitigated these effects.
Conclusion
This study demonstrates that leptin stimulates the growth and metastasis of TNBC through the activation of both LEPR and ADRB2, resulting in increased ROS production. These findings highlight LEPR and ADRB2 as potential biomarkers and therapeutic targets in TNBC.
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Harnessing Institutionally Developed Clinical Targeted Sequencing to Improve Patient Survival in Breast Cancer: A Seven-Year Experience
Jiwon Koh, Jinyong Kim, Go-Un Woo, Hanbaek Yi, So Yean Kwon, Jeongmin Seo, Jeong Mo Bae, Jung Ho Kim, Jae Kyung Won, Han Suk Ryu, Yoon Kyung Jeon, Dae-Won Lee, Miso Kim, Tae-Yong Kim, Kyung-Hun Lee, Tae-You Kim, Jee-Soo Lee, Moon-Woo Seong, Sheehyun Kim, Sungyoung Lee, Hongseok Yun, Myung Geun Song, Jaeyong Choi, Jong-Il Kim, Seock-Ah Im
Cancer Res Treat. 2025;57(2):443-456.   Published online August 21, 2024
DOI: https://doi.org/10.4143/crt.2024.296
AbstractAbstract PDFSupplementary MaterialPubReaderePub
Purpose
Considering the high disease burden and unique features of Asian patients with breast cancer (BC), it is essential to have a comprehensive view of genetic characteristics in this population. An institutional targeted sequencing platform was developed through the Korea Research-Driven Hospitals project and was incorporated into clinical practice. This study explores the use of targeted next-generation sequencing (NGS) and its outcomes in patients with advanced/metastatic BC in the real world.
Materials and Methods
We reviewed the results of NGS tests administered to BC patients using a customized sequencing platform—FiRST Cancer Panel (FCP)—over 7 years. We systematically described clinical translation of FCP for precise diagnostics, personalized therapeutic strategies, and unraveling disease pathogenesis.
Results
NGS tests were conducted on 548 samples from 522 patients with BC. Ninety-seven point six percentage of tested samples harbored at least one pathogenic alteration. The common alterations included mutations in TP53 (56.2%), PIK3CA (31.2%), GATA3 (13.8%), BRCA2 (10.2%), and amplifications of CCND1 (10.8%), FGF19 (10.0%), and ERBB2 (9.5%). NGS analysis of ERBB2 amplification correlated well with human epidermal growth factor receptor 2 immunohistochemistry and in situ hybridization. RNA panel analyses found potentially actionable and prognostic fusion genes. FCP effectively screened for potentially germline pathogenic/likely pathogenic mutation. Ten point three percent of BC patients received matched therapy guided by NGS, resulting in a significant overall survival advantage (p=0.022), especially for metastatic BCs.
Conclusion
Clinical NGS provided multifaceted benefits, deepening our understanding of the disease, improving diagnostic precision, and paving the way for targeted therapies. The concrete advantages of FCP highlight the importance of multi-gene testing for BC, especially for metastatic conditions.
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Special Article
Trends in Cancer-Screening Rates in Korea: Findings from the National Cancer Screening Survey, 2004-2023
EunKyo Kang, Kui Son Choi, Jae Kwan Jun, Yeol Kim, Hyeon Ji Lee, Chang Kyun Choi, Tae Hee Kim, Sun Hwa Lee, Mina Suh
Cancer Res Treat. 2025;57(1):28-38.   Published online August 2, 2024
DOI: https://doi.org/10.4143/crt.2024.325
AbstractAbstract PDFSupplementary MaterialPubReaderePub
Purpose
This study aimed to report the overall national trends in the rates of cancer screening based on recommendations and provide insights into the changing trends of these rates across different demographics.
Materials and Methods
This study used data from the Korean National Cancer Screening Survey (KNCSS), which surveys nationwide cancer-screening rates and includes 4,500 individuals meeting the Korean National Cancer Screening Program (NCSP) protocol age criteria. Cancer-screening rates were assessed using structured questionnaires; yearly trends were analyzed for both lifetime cancer-screening rates and rates of screening based on recommendations, and subgroup analyses were performed based on age and sex.
Results
The rates of cancer screening based on recommendations showed significant increments: the stomach cancer-screening rate increased from 39.2% in 2004 to 77.5% in 2023 (3.50% per year), the liver cancer-screening rate increased from 20.0% to 48.8% (4.30% per year), and the colorectal cancer, increased from 19.9% to 70.7% (5.15% per year). The breast cancer-screening rate increased from 33.2% to 72.7% (2.88% per year), and the cervical cancer, increased from 58.3% to 70.2% (1.08% per year). Despite some differences, particularly in relation to sociodemographic factors, screening rates increased significantly for all cancer types.
Conclusion
Cancer-screening rates in Korea increased consistently from 2004 to 2023, demonstrating the effectiveness of the national cancer-screening program. However, the increments in breast, cervical and lung cancer-screening rates were relatively lower, indicating the need for additional efforts and strategies.

Citations

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  • Association Between Suicidal Ideation and Cancer Screening Uptake: Results from Middle-Aged and Older Adults in Korea
    Seong-Uk Baek, Jin-Ha Yoon
    Cancers.2025; 17(6): 956.     CrossRef
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Original Articles
Breast cancer
Locoregional Recurrence in Adenoid Cystic Carcinoma of the Breast: A Retrospective, Multicenter Study (KROG 22-14)
Sang Min Lee, Bum-Sup Jang, Won Park, Yong Bae Kim, Jin Ho Song, Jin Hee Kim, Tae Hyun Kim, In Ah Kim, Jong Hoon Lee, Sung-Ja Ahn, Kyubo Kim, Ah Ram Chang, Jeanny Kwon, Hae Jin Park, Kyung Hwan Shin
Cancer Res Treat. 2025;57(1):150-158.   Published online July 12, 2024
DOI: https://doi.org/10.4143/crt.2024.201
AbstractAbstract PDFPubReaderePub
Purpose
This study aims to evaluate the treatment approaches and locoregional patterns for adenoid cystic carcinoma (ACC) in the breast, which is an uncommon malignant tumor with limited clinical data.
Materials and Methods
A total of 93 patients diagnosed with primary ACC in the breast between 1992 and 2022 were collected from multi-institutions. All patients underwent surgical resection, including breast-conserving surgery (BCS) or total mastectomy (TM). Recurrence patterns and locoregional recurrence-free survival (LRFS) were assessed.
Results
Seventy-five patients (80.7%) underwent BCS, and 71 of them (94.7%) received post-operative radiation therapy (PORT). Eighteen patients (19.3%) underwent TM, with five of them (27.8%) also receiving PORT. With a median follow-up of 50 months, the LRFS rate was 84.2% at 5 years. Local recurrence (LR) was observed in five patients (5.4%) and four cases (80%) of the LR occurred in the tumor bed. Three of LR (3/75, 4.0%) had a history of BCS and PORT, meanwhile, two of LR (2/18, 11.1%) had a history of mastectomy. Regional recurrence occurred in two patients (2.2%), and both cases had a history of PORT with (n=1) and without (n=1) irradiation of the regional lymph nodes. Partial breast irradiation (p=0.35), BCS (p=0.96) and PORT in BCS group (p=0.33) had no significant association with LRFS.
Conclusion
BCS followed by PORT was the predominant treatment approach for ACC of the breast and LR mostly occurred in the tumor bed. The findings of this study suggest that partial breast irradiation might be considered for PORT in primary breast ACC.

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  • Adenoid Cystic Carcinoma of the Breast: A Narrative Review and Update on Management
    Taylor Neilson, Zaibo Li, Christina Minami, Sara P. Myers
    Cancers.2025; 17(7): 1079.     CrossRef
  • 1,441 View
  • 129 Download
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A Single-Arm Phase II Clinical Trial of Fulvestrant Combined with Neoadjuvant Chemotherapy of ER+/HER2– Locally Advanced Breast Cancer: Integrated Analysis of 18F-FES PET-CT and Metabolites with Treatment Response
Qing Shao, Ningning Zhang, Xianjun Pan, Wenqi Zhou, Yali Wang, Xiaoliang Chen, Jing Wu, Xiaohua Zeng
Cancer Res Treat. 2025;57(1):126-139.   Published online July 9, 2024
DOI: https://doi.org/10.4143/crt.2023.1251
AbstractAbstract PDFSupplementary MaterialPubReaderePub
Purpose
This Phase II trial was objected to evaluate the efficacy and safety of adding fulvestrant to neoadjuvant chemotherapy in patients with estrogen receptor (ER)+/human epidermal growth factor receptor 2 (HER2)– locally advanced breast cancer (LABC). Additionally, the study aimed to investigate the association of 16α-18F-fluoro-17β-fluoroestradiol (18F-FES) positron emission tomography (PET)–computed tomography (CT) and metabolites with efficacy.
Materials and Methods
Fulvestrant and EC-T regimen were given to ER+/HER2– LABC patients before surgery. At baseline, patients received 18F-FES PET-CT scan, and plasma samples were taken for liquid chromatography–mass spectrometry analysis. The primary endpoint was objective response rate (ORR). Secondary endpoints included total pathologic complete response (tpCR) and safety.
Results
Among the 36 patients enrolled, the ORR was 86.1%, the tpCR rate was 8.3%. The incidence of grade ≥ 3 treatment-emergent adverse events was 22%. The decrease in ER value in sensitive patients was larger than that in non-sensitive patients, as was Ki-67 (p < 0.05). The maximum standardized uptake value, mean standardized uptake values, total lesion ER expression of 18F-FES PET-CT in sensitive patients were significantly higher than those in non-sensitive patients (p < 0.05). Moreover, these parameters were significantly correlated with Miller and Payne grade and the change in ER expression before and after treatment (p < 0.05). Thirteen differential expressed metabolites were identified, which were markedly enriched in 19 metabolic pathways.
Conclusion
This regimen demonstrated acceptable toxicity and encouraging antitumor efficacy. 18F-FES PET-CT might serve as a tool to predict the effectiveness of this therapy. Altered metabolites or metabolic pathways might be associated with treatment response.
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Molecular Classification of Breast Cancer Using Weakly Supervised Learning
Wooyoung Jang, Jonghyun Lee, Kyong Hwa Park, Aeree Kim, Sung Hak Lee, Sangjeong Ahn
Cancer Res Treat. 2025;57(1):116-125.   Published online June 25, 2024
DOI: https://doi.org/10.4143/crt.2024.113
AbstractAbstract PDFSupplementary MaterialPubReaderePub
Purpose
The molecular classification of breast cancer is crucial for effective treatment. The emergence of digital pathology has ushered in a new era in which weakly supervised learning leveraging whole-slide images has gained prominence in developing deep learning models because this approach alleviates the need for extensive manual annotation. Weakly supervised learning was employed to classify the molecular subtypes of breast cancer.
Materials and Methods
Our approach capitalizes on two whole-slide image datasets: one consisting of breast cancer cases from the Korea University Guro Hospital (KG) and the other originating from The Cancer Genomic Atlas dataset (TCGA). Furthermore, we visualized the inferred results using an attention-based heat map and reviewed the histomorphological features of the most attentive patches.
Results
The KG+TCGA-trained model achieved an area under the receiver operating characteristics value of 0.749. An inherent challenge lies in the imbalance among subtypes. Additionally, discrepancies between the two datasets resulted in different molecular subtype proportions. To mitigate this imbalance, we merged the two datasets, and the resulting model exhibited improved performance. The attentive patches correlated well with widely recognized histomorphologic features. The triple-negative subtype has a high incidence of high-grade nuclei, tumor necrosis, and intratumoral tumor-infiltrating lymphocytes. The luminal A subtype showed a high incidence of collagen fibers.
Conclusion
The artificial intelligence (AI) model based on weakly supervised learning showed promising performance. A review of the most attentive patches provided insights into the predictions of the AI model. AI models can become invaluable screening tools that reduce costs and workloads in practice.
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Endoxifen Concentration Is Associated with Recurrence-Free Survival in Hormone-Sensitive Breast Cancer Patients
Beomki Lee, Seok Jin Nam, Seok Won Kim, Jonghan Yu, Byung-Joo Chae, Se Kyung Lee, Jai Min Ryu, Jeong Eon Lee, Soo-Youn Lee
Cancer Res Treat. 2025;57(1):140-149.   Published online June 18, 2024
DOI: https://doi.org/10.4143/crt.2023.1285
AbstractAbstract PDFPubReaderePub
Purpose
The metabolism of tamoxifen is influenced by various cytochrome p450 enzymes, including CYP2D6 and CYP2C19, leading to variations in the levels of endoxifen, even with the same tamoxifen dose. However, the clinical significance of endoxifen for the prognosis of breast cancer patients remains controversial. This study aimed to elucidate the relevance of endoxifen level to recurrence-free survival censored with tamoxifen discontinuation (RFSt), representing the RFS for tamoxifen itself, of breast cancer patients and determine a suitable cutoff for prognostication.
Materials and Methods
The study included 478 breast cancer patients. Tamoxifen and its metabolites, including endoxifen, were measured using liquid chromatography-tandem mass spectrometry. An optimal cutoff was determined with maximally selected rank statistics. Survival analysis and Cox regression were conducted based on this cutoff.
Results
An endoxifen level of 21.00 ng/mL was the optimal cutoff for prognostication. Survival analysis revealed a statistically significant difference in RFSt between the low endoxifen group (≤ 21.00 ng/mL) and the high endoxifen group (> 21.00 ng/mL) (log-rank test, p=0.032). The 10-year probability of RFSt was 83.2% (95% confidence interval [CI], 77.0 to 89.9) and 88.3% (95% CI, 83.3 to 93.5) in the low and high endoxifen groups, respectively. Multivariable Cox proportional hazards regression indicated endoxifen concentration as a significant factor associated with prognosis.
Conclusion
Endoxifen could serve as a marker for appropriate tamoxifen treatment with a cutoff of 21.00 ng/mL. Based on this cutoff, therapeutic drug monitoring would benefit patients displaying suboptimal endoxifen concentrations.
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A 10-Gene Signature to Predict the Prognosis of Early-Stage Triple-Negative Breast Cancer
Chang Min Kim, Kyong Hwa Park, Yun Suk Yu, Ju Won Kim, Jin Young Park, Kyunghee Park, Jong-Han Yu, Jeong Eon Lee, Sung Hoon Sim, Bo Kyoung Seo, Jin Kyeoung Kim, Eun Sook Lee, Yeon Hee Park, Sun-Young Kong
Cancer Res Treat. 2024;56(4):1113-1125.   Published online May 10, 2024
DOI: https://doi.org/10.4143/crt.2024.100
AbstractAbstract PDFSupplementary MaterialPubReaderePub
Purpose
Triple-negative breast cancer (TNBC) is a particularly challenging subtype of breast cancer, with a poorer prognosis compared to other subtypes. Unfortunately, unlike luminal-type cancers, there is no validated biomarker to predict the prognosis of patients with early-stage TNBC. Accurate biomarkers are needed to establish effective therapeutic strategies.
Materials and Methods
In this study, we analyzed gene expression profiles of tumor samples from 184 TNBC patients (training cohort, n=76; validation cohort, n=108) using RNA sequencing.
Results
By combining weighted gene expression, we identified a 10-gene signature (DGKH, GADD45B, KLF7, LYST, NR6A1, PYCARD, ROBO1, SLC22A20P, SLC24A3, and SLC45A4) that stratified patients by risk score with high sensitivity (92.31%), specificity (92.06%), and accuracy (92.11%) for invasive disease-free survival. The 10-gene signature was validated in a separate institution cohort and supported by meta-analysis for biological relevance to well-known driving pathways in TNBC. Furthermore, the 10-gene signature was the only independent factor for invasive disease-free survival in multivariate analysis when compared to other potential biomarkers of TNBC molecular subtypes and T-cell receptor β diversity. 10-gene signature also further categorized patients classified as molecular subtypes according to risk scores.
Conclusion
Our novel findings may help address the prognostic challenges in TNBC and the 10-gene signature could serve as a novel biomarker for risk-based patient care.

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  • Significance of Multi-Cancer Genome Profiling Testing for Breast Cancer: A Retrospective Analysis of 3326 Cases from Japan’s National Database
    Kyoka Kawabata, Hinano Nishikubo, Saki Kanei, Rika Aoyama, Yuki Tsukada, Tomoya Sano, Daiki Imanishi, Takashi Sakuma, Koji Maruo, Yurie Yamamoto, Qiang Wang, Zhonglin Zhu, Canfeng Fan, Masakazu Yashiro
    Genes.2024; 15(6): 792.     CrossRef
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  • 149 Download
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Dural Metastasis in Breast Cancer: MRI-Based Morphological Subtypes and Their Clinical Implications
Sung Jun Ahn, Bio Joo, Mina Park, Hun Ho Park, Sang Hyun Suh, Sung Gwe Ahn, Jihwan Yoo
Cancer Res Treat. 2024;56(4):1105-1112.   Published online March 19, 2024
DOI: https://doi.org/10.4143/crt.2024.138
AbstractAbstract PDFSupplementary MaterialPubReaderePub
Purpose
This study aimed to investigate the clinical factors associated with breast cancer (BRCA) dural metastases (DMs), their impact on prognosis compared to brain parenchymal metastases (BPMs) alone, and differences between DM subtypes, aiming to inform clinical decisions.
Materials and Methods
We retrospectively analyzed 119 patients with BRCA with brain metastasis, including 91 patients with BPM alone and 28 patients with DM. Univariate and multivariate analyses were performed to compare the clinical characteristics between the two groups and within subtypes of DM. Overall survival after DM (OSDM) and the interval from DM to leptomeningeal carcinomatosis (LMC) were compared using Kaplan-Meier analysis.
Results
DM was notably linked with extracranial metastasis, luminal-like BRCA subtype (p=0.033), and skull metastases (p < 0.001). Multiple logistic regression revealed a strong association of DM with extracranial and skull metastases, but not with subtype or hormone receptor status. Patients with DM did not show survival differences compared with patients with BPM alone. In the subgroup analysis, nodular-type DM correlated with human epidermal growth factor receptor 2 status (p=0.044), whereas diffuse-type DM was significantly associated with a higher prevalence of the luminal-like subtype (p=0.048) and the presence of skull metastasis (p=0.002). Patients with diffuse DM did not exhibit a significant difference in OSDM but had a notably shorter interval from DM to LMC compared to those with nodular DM (p=0.049).
Conclusion
While the impact of DM on the overall prognosis of patients with BRCA is minimal, our findings underscore distinct characteristics and prognostic outcomes within DM subgroups.

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  • Small-cell neuroendocrine carcinoma of the cervix with leptomeningeal spread: A rare coincidence report and literature review
    Mohammed A. Azab, Oday Atallah, Nour El-Gohary, Ahmed Hazim, Hamed Abdelma’aboud Mostafa
    Surgical Neurology International.2024; 15: 310.     CrossRef
  • Left homonymous hemianopia as an atypical manifestation of isolated pachymeningeal metastasis secondary to breast cancer: Case report and review of the literature
    Aziz Ahizoune, Moad Belouad, Houda Alloussi, Mohamed Allaoui, Mohamed Hamid, Ahmed Bourazza
    Radiology Case Reports.2024; 19(11): 5459.     CrossRef
  • 1,541 View
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A Nationwide Study on HER2-Low Breast Cancer in South Korea: Its Incidence of 2022 Real World Data and the Importance of Immunohistochemical Staining Protocols
Min Chong Kim, Eun Yoon Cho, So Yeon Park, Hee Jin Lee, Ji Shin Lee, Jee Yeon Kim, Ho-chang Lee, Jin Ye Yoo, Hee Sung Kim, Bomi Kim, Wan Seop Kim, Nari Shin, Young Hee Maeng, Hun Soo Kim, Sun Young Kwon, Chungyeul Kim, Sun-Young Jun, Gui Young Kwon, Hye Jeong Choi, So Mang Lee, Ji Eun Choi, Ae Ri An, Hyun Joo Choi, EunKyung Kim, Ahrong Kim, Ji-Young Kim, Jeong Yun Shim, Gyungyub Gong, Young Kyung Bae
Cancer Res Treat. 2024;56(4):1096-1104.   Published online March 6, 2024
DOI: https://doi.org/10.4143/crt.2024.092
AbstractAbstract PDFSupplementary MaterialPubReaderePub
Purpose
Notable effectiveness of trastuzumab deruxtecan in patients with human epidermal growth factor receptor 2 (HER2)–low advanced breast cancer (BC) has focused pathologists’ attention. We studied the incidence and clinicopathologic characteristics of HER2-low BC, and the effects of immunohistochemistry (IHC) associated factors on HER2 IHC results.
Materials and Methods
The Breast Pathology Study Group of the Korean Society of Pathologists conducted a nationwide study using real-world data on HER2 status generated between January 2022 and December 2022. Information on HER2 IHC protocols at each participating institution was also collected.
Results
Total 11,416 patients from 25 institutions included in this study. Of these patients, 40.7% (range, 6.0% to 76.3%) were classified as HER2-zero, 41.7% (range, 10.5% to 69.1%) as HER2-low, and 17.5% (range, 6.7% to 34.0%) as HER2-positive. HER2-low tumors were associated with positive estrogen receptor and progesterone receptor statuses (p < 0.001 and p < 0.001, respectively). Antigen retrieval times (≥ 36 minutes vs. < 36 minutes) and antibody incubation times (≥ 12 minutes vs. < 12 minutes) affected on the frequency of HER2 IHC 1+ BC at institutions using the PATHWAY HER2 (4B5) IHC assay and BenchMark XT or Ultra staining instruments. Furthermore, discordant results between core needle biopsy and subsequent resection specimen HER2 statuses were observed in 24.1% (787/3,259) of the patients.
Conclusion
The overall incidence of HER2-low BC in South Korea concurs with those reported in previously published studies. Significant inter-institutional differences in HER2 IHC protocols were observed, and it may have impact on HER2-low status. Thus, we recommend standardizing HER2 IHC conditions to ensure precise patient selection for targeted therapy.

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  • Impact of immunohistochemistry staining conditions on the incidence of human epidermal growth factor receptor 2 (HER2)-low breast cancer
    Min Chong Kim, Sun Young Kwon, Hye Ra Jung, Young Kyung Bae
    Virchows Archiv.2024; 485(6): 1117.     CrossRef
  • Breast Cancer: Extracellular Matrix and Microbiome Interactions
    Lourdes Herrera-Quintana, Héctor Vázquez-Lorente, Julio Plaza-Diaz
    International Journal of Molecular Sciences.2024; 25(13): 7226.     CrossRef
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Implementation of BRCA Test among Young Breast Cancer Patients in South Korea: A Nationwide Cohort Study
Yung-Huyn Hwang, Tae-Kyung Yoo, Sae Byul Lee, Jisun Kim, Beom Seok Ko, Hee Jeong Kim, Jong Won Lee, Byung Ho Son, Il Yong Chung
Cancer Res Treat. 2024;56(3):802-808.   Published online February 19, 2024
DOI: https://doi.org/10.4143/crt.2023.1186
AbstractAbstract PDFSupplementary MaterialPubReaderePub
Purpose
This study aimed to investigate the frequency of BRCA testing and related factors among young breast cancer patients (age < 40 years) in South Korea.
Materials and Methods
We conducted a nationwide retrospective cohort study using data from the Health Insurance Review and Assessment claims. Newly diagnosed breast cancer patients younger than 40 were included. Annual BRCA testing ratios (number of BRCA test recipients/the number of patients undergoing breast cancer surgery in each year) were analyzed by region and health care delivery system. We investigated the location of breast cancer diagnosis and BRCA testing.
Results
From January 2010 to December 2020, there were 25,665 newly diagnosed young breast cancer patients, of whom 12,186 (47.5%) underwent BRCA testing. The BRCA testing ratios increased gradually from 0.084 (154/1,842) in 2010 to 0.961 (1,975/2,055) in 2020. Medical aid (vs. health insurance) and undergoing surgery in metropolitan cities or others (vs. Seoul), general hospitals, and clinics (vs. tertiary hospitals) were associated with a lower likelihood of BRCA testing. While 97.8% of the patients diagnosed in Seoul underwent BRCA testing in Seoul, 22.9% and 29.2% of patients who were diagnosed in metropolitan areas and other regions moved to Seoul and underwent BRCA testing, respectively.
Conclusion
The frequency of BRCA testing has increased over time in South Korea, with Seoul showing a particularly high rate of testing. About one-quarter of patients diagnosed with breast cancer outside of Seoul moved to Seoul and underwent BRCA testing.
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Review Article
HER2-Low Breast Cancer: Now and in the Future
Sora Kang, Sung-Bae Kim
Cancer Res Treat. 2024;56(3):700-720.   Published online January 30, 2024
DOI: https://doi.org/10.4143/crt.2023.1138
AbstractAbstract PDFPubReaderePub
Breast cancer is a heterogeneous disease, and its subtypes are characterized by hormone receptor and human epidermal growth factor receptor 2 (HER2) expression status. “HER2-low” tumors, which exhibit a low level of HER2 expression (immunohistochemistry 1+ or 2+ without gene amplification), were conventionally considered not amenable to anti-HER2 targeting agents based on the results of a phase III trial of trastuzumab. However, this perspective is being challenged by the emergence of novel anti-HER2 antibody-drug conjugates, such as trastuzumab-deruxtecan. These innovative therapies have demonstrated remarkable efficacy against HER2-low breast cancer, shedding new light on a previously overlooked category of breast cancer. Such promising results highlight the need for in-depth investigations of the biology and prognostic implications of HER2-low tumors. In this review, we comprehensively summarize the current evidence surrounding this topic and highlight areas that warrant further exploration and research in the future.

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  • The impact of the new histological classification of breast cancer with the introduction of HER 2 low status
    Myriam Doucet, Marion De Berti, Flavie Arbion, Caroline Goupille, Gilles Body, Lobna Ouldamer
    Journal of Gynecology Obstetrics and Human Reproduction.2025; 54(4): 102928.     CrossRef
  • Study on the Efficacy of HER-2 Expression in Neoadjuvant Chemotherapy for HER2-Negative Breast Cancer
    伟康 于
    Advances in Clinical Medicine.2025; 15(02): 1690.     CrossRef
  • Toxicities and management strategies of emerging antibody–drug conjugates in breast cancer
    Sora Kang, Sung-Bae Kim
    Therapeutic Advances in Medical Oncology.2025;[Epub]     CrossRef
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Original Articles
Breast cancer
PD-L1 (SP142) Expression in Primary and Recurrent/Metastatic Triple-Negative Breast Cancers and Its Clinicopathological Significance
Eun Kyung Han, Ji Won Woo, Koung Jin Suh, Se Hyun Kim, Jee Hyun Kim, So Yeon Park
Cancer Res Treat. 2024;56(2):557-566.   Published online December 12, 2023
DOI: https://doi.org/10.4143/crt.2023.1025
AbstractAbstract PDFPubReaderePub
Purpose
The programmed death-ligand 1 (PD-L1) SP142 assay identifies patients with triple-negative breast cancer (TNBC) who are most likely to respond to the anti–PD-L1 agent atezolizumab. We aimed to compare PD-L1 (SP142) expression between primary and recurrent/metastatic TNBCs and elucidate the clinicopathological features associated with its expression.
Materials and Methods
Primary and recurrent/metastatic TNBCs tested with PD-L1 (SP142) were collected, and clinicopathological information of these cases was obtained through a review of slides and medical records.
Results
PD-L1 (SP142) positivity was observed in 50.9% (144/283) of primary tumors and 37.8% (31/82) of recurrent/metastatic TNBCs with a significant difference. Recurrent or metastatic sites were associated with PD-L1 positivity, with high PD-L1 positivity in the lung, breast, and soft tissues, and low positivity in the bone, skin, liver, and brain. When comparing PD-L1 expression between primary and matched recurrent/metastatic TNBCs using 55 paired samples, 20 cases (36.4%) showed discordance; 10 cases revealed positive conversion, and another 10 cases revealed negative conversion during metastatic progression. In primary TNBCs, PD-L1 expression was associated with a higher histologic grade, lower T category, pushing border, and higher tumor-infiltrating lymphocyte infiltration. In survival analyses, PD-L1 positivity, especially high positivity, was found to be associated with favorable prognosis of patients.
Conclusion
PD-L1 (SP142) expression was lower in recurrent/metastatic TNBCs, and substantial cases showed discordance in its expression between primary and recurrent/metastatic sites, suggesting that multiple sites may need to be tested for PD-L1 (SP142) when considering atezolizumab therapy. PD-L1 (SP142)–positive TNBCs seems to be associated with favorable clinical outcomes.

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  • Discrepancy of PD1/ PD-L1 status between primary and metastatic triple negative breast cancer in diagnostic biopsies
    Manar Moustafa, Basma Hamed Ibrahim
    Revista de Senología y Patología Mamaria.2025; 38(3): 100680.     CrossRef
  • Solamargine inhibits gastric cancer progression via inactivation of STAT3/PD‑L1 signaling
    Xiongxiang Liu, Lin Song, Wen Liu, Bin Liu, Lang Liu, Yao Su
    Molecular Medicine Reports.2024;[Epub]     CrossRef
  • Prevalence of Programmed Death-Ligand 1 Positivity Using SP142 in Patients With Advanced Stage Triple-Negative Breast Cancer in Malaysia: A Cross-Sectional Study
    Pathmanathan Rajadurai, Ning Yi Yap, Seow Fan Chiew, Reena Rahayu Md Zin, Suria Hayati Md Pauzi, Aniqah Shamimi Binti Jaafar, Azyani Yahaya, Lai Meng Looi
    Journal of Breast Cancer.2024; 27(6): 362.     CrossRef
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Genomic Characteristics and Its Therapeutic Implications in Breast Cancer Patients with Detectable Molecular Residual Disease
Shu Zhang, Yan Jiang, Lu Zhou, Jing Xu, Gang Zhang, Lu Shen, Yan Xu
Cancer Res Treat. 2024;56(2):538-548.   Published online December 5, 2023
DOI: https://doi.org/10.4143/crt.2023.1059
AbstractAbstract PDFSupplementary MaterialPubReaderePub
Purpose
Molecular residual disease (MRD) is the main cause of postoperative recurrence of breast cancer. However, the baseline tumor genomic characteristics and therapeutic implications of breast cancer patients with detectable MRD after surgery are still unknown.
Materials and Methods
In this study, we enrolled 80 patients with breast cancer who underwent next-generation sequencing-based genetic testing of 1,021 cancer-related genes performed on baseline tumor and postoperative plasma, among which 18 patients had detectable MRD after surgery.
Results
Baseline clinical characteristics found that patients with higher clinical stages were more likely to have detectable MRD. Analysis of single nucleotide variations and small insertions/deletions in baseline tumors showed that somatic mutations in MAP3K1, ATM, FLT1, GNAS, POLD1, SPEN, and WWP2 were significantly enriched in patients with detectable MRD. Oncogenic signaling pathway analysis revealed that alteration of the Cell cycle pathway was more likely to occur in patients with detectable MRD (p=0.012). Mutational signature analysis showed that defective DNA mismatch repair and activation-induced cytidine deaminase (AID) mediated somatic hypermutation (SHM) were associated with detectable MRD. According to the OncoKB database, 77.8% (14/18) of patients with detectable MRD had U.S. Food and Drug Administration–approved mutational biomarkers and targeted therapy.
Conclusion
Our study reports genomic characteristics of breast cancer patients with detectable MRD. The cell cycle pathway, defective DNA mismatch repair, and AID-mediated SHM were found to be the possible causes of detectable MRD. We also found the vast majority of patients with detectable MRD have the opportunity to access targeted therapy.
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Implication of Pre- and Post-radiotherapy ctDNA Dynamics in Patients with Residual Triple-Negative Breast Cancer at Surgery after Neoadjuvant Chemotherapy: Findings from a Prospective Observational Study
Tae Hoon Lee, Haeyoung Kim, Yeon Jeong Kim, Woong-Yang Park, Won Park, Won Kyung Cho, Nalee Kim
Cancer Res Treat. 2024;56(2):531-537.   Published online November 10, 2023
DOI: https://doi.org/10.4143/crt.2023.996
AbstractAbstract PDFPubReaderePub
Purpose
This study aims to determine the association between pre- and postoperative radiotherapy (PORT) circulating tumor DNA (ctDNA) dynamics and oncological outcomes in patients with residual triple-negative breast cancer who underwent surgery after neoadjuvant chemotherapy (NAC).
Materials and Methods
Between March 2019 and July 2020, 11 nonmetastatic patients with residual disease who underwent surgery after NAC were prospectively enrolled. In each patient, tumor specimens obtained during surgery and blood samples collected at three time points during PORT (T0: pre-PORT, T1: 3 weeks after PORT, T2: 1 month after PORT) were sequenced, targeting 38 cancer-related genes. Disease-free survival (DFS) was evaluated and the association between DFS and ctDNA dynamics was analyzed.
Results
At T0, ctDNA was detected in three (27.2%) patients. The ctDNA dynamics were as follows: two showed a decreasing ctDNA variant allele frequency (VAF) and reached zero VAF at T2, while one patient exhibited an increasing VAF during PORT and maintained an elevated VAF at T2. After a median follow-up of 48 months, two patients experienced distant metastasis without any locoregional failures. All failures occurred in patients with ctDNA positivity at T0 and a decreased VAF after PORT. The 4-year DFS rates according to the T0 ctDNA status were 67% (positive ctDNA) and 100% (negative ctDNA) (p=0.032).
Conclusion
More than a quarter of the patients with residual disease after post-NAC surgery exhibited pre-PORT ctDNA positivity, and ctDNA positivity was associated with poor DFS. For patients with pre-PORT ctDNA positivity, the administration of a more effective systemic treatment should be considered.

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  • Role of circulating tumor DNA in early-stage triple-negative breast cancer: a systematic review and meta-analysis
    Diana Zhang, Shayesteh Jahanfar, Judy B. Rabinowitz, Joshua Dower, Fei Song, Cherng-Horng Wu, Xiao Hu, Phillip Tracy, Mark Basik, Arielle Medford, Po-Han Lin, Chiun-Sheng Huang, Francois-Clement Bidard, Shufang Renault, Lori Pai, Mary Buss, Heather A. Par
    Breast Cancer Research.2025;[Epub]     CrossRef
  • Multiple drugs

    Reactions Weekly.2024; 2033(1): 183.     CrossRef
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Temporal Trend in Uptake of the National General Health Checkups and Cancer Screening Program among Korean Women with Breast Cancer
Thi Xuan Mai Tran, Soyeoun Kim, Chihwan Cha, Boyoung Park
Cancer Res Treat. 2024;56(2):522-530.   Published online October 30, 2023
DOI: https://doi.org/10.4143/crt.2023.729
AbstractAbstract PDFSupplementary MaterialPubReaderePub
Purpose
This study assessed the temporal trends of uptake of national general health and cancer screening among women with breast cancer in Korea between 2009 and 2016.
Materials and Methods
We retrospectively analyzed the claims data from the Korean National Health Insurance Service database. Participants included 101,403 breast cancer patients diagnosed between 2009 and 2016. Information on participation in national screening programs, including breast cancer screening, general health, and gastric, colorectal, and cervical cancers, up to 2020 was collected. Screening participation rates within the first 2 and 5 years postdiagnosis were calculated by diagnosis year and fitted with joinpoint regression models to assess temporal trends.
Results
Overall, the participation rate in breast cancer screening within 2 years postdiagnosis increased from 10.9% to 14.0% from 2009-2016, with an annual percentage change (APC) of 3.7% (p < 0.05). The participation rate in breast cancer screening was lower than that in general health checkup and screening for other cancers within 2 and 5 years postdiagnosis. A steady increase in screening trends was also observed for general health, gastric, colorectal, and cervical cancers, with APC of 5.3%, 5.7%, 6.9%, and 7.6% in the 2-year postdiagnosis rate, and APC of 3.6%, 3.7%, 3.7%, and 4.4% in 5-year postdiagnosis rate, respectively. The screening rate was highest among age groups 50-59 and 60-69 in 2009 and significant upward trends were observed in all age groups for general health checkup and gastric, colorectal, and cervical cancer screening.
Conclusion
Among female breast cancer survivors in Korea, the uptake rate of screenings for general health and various cancers, including breast, gastric, colorectal, and cervical cancers, has shown a gradual increase in recent years.

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  • Identifying potential medical aid beneficiaries using machine learning: A Korean Nationwide cohort study
    Junmo Kim, Su Hyun Park, Hyesu Lee, Su Kyoung Lee, Jihye Kim, Suhyun Kim, Yong Jin Kwon, Kwangsoo Kim
    International Journal of Medical Informatics.2025; 195: 105775.     CrossRef
  • Screening Adherence for Second Primary Malignancies in Breast Cancer Survivors: Behaviors, Facilitators, and Barriers to Enhance Quality Care
    Fernanda Mesa-Chavez, Misael Salazar-Alejo, Cynthia Villarreal-Garza
    Seminars in Oncology.2024; 51(5-6): 156.     CrossRef
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Pyrotinib Combined with Vinorelbine in Patients with Previously Treated HER2-Positive Metastatic Breast Cancer: A Multicenter, Single-Arm, Prospective Study
Kuikui Jiang, Ruoxi Hong, Wen Xia, Qianyi Lu, Liang Li, Jianhao Huang, Yanxia Shi, Zhongyu Yuan, Qiufan Zheng, Xin An, Cong Xue, Jiajia Huang, Xiwen Bi, Meiting Chen, Jingmin Zhang, Fei Xu, Shusen Wang
Cancer Res Treat. 2024;56(2):513-521.   Published online October 12, 2023
DOI: https://doi.org/10.4143/crt.2023.786
AbstractAbstract PDFPubReaderePub
Purpose
This study aims to evaluate the efficacy and safety of a new combination treatment of vinorelbine and pyrotinib in human epidermal growth factor receptor 2 (HER2)–positive metastatic breast cancer (MBC) and provide higher level evidence for clinical practice.
Materials and Methods
This was a prospective, single-arm, phase 2 trial conducted at three institutions in China. Patients with HER2-positive MBC, who had previously been treated with trastuzumab plus a taxane or trastuzumab plus pertuzumab combined with a chemotherapeutic agent, were enrolled between March 2020 and December 2021. All patients received pyrotinib 400 mg orally once daily plus vinorelbine 25 mg/m2 intravenously or 60-80 mg/m2 orally on day 1 and day 8 of 21-day cycle. The primary endpoint was progression-free survival (PFS), and the secondary endpoints included the objective response rate (ORR), disease control rate (DCR), overall survival, and safety.
Results
A total of 39 patients were enrolled. All patients had been pretreated with trastuzumab and 23.1% (n=9) of them had accepted trastuzumab plus pertuzumab. The median follow-up time was 16.3 months (95% confidence interval [CI], 5.3 to 27.2), and the median PFS was 6.4 months (95% CI, 4.0 to 8.8). The ORR was 43.6% (95% CI, 27.8% to 60.4%) and the DCR was 84.6% (95% CI, 69.5% to 94.1%). The median PFS of patients with versus without prior pertuzumab treatment was 4.6 and 8.3 months (p=0.017). The most common grade 3/4 adverse events were diarrhea (28.2%), neutrophil count decreased (15.4%), white blood cell count decreased (7.7%), vomiting (5.1%), and anemia (2.6%).
Conclusion
Pyrotinib plus vinorelbine showed promising efficacy and tolerable toxicity as second-line treatment in patients with HER2-positive MBC.

Citations

Citations to this article as recorded by  
  • Combination Therapy of Pyrotinib and Metronomic Vinorelbine in HER2+ Advanced Breast Cancer after Trastuzumab Failure (PROVE): A Prospective Phase 2 Study
    Chunfang Hao, Xu Wang, Yehui Shi, Zhongsheng Tong, Shufen Li, Xiaodong Liu, Lan Zhang, Jie Zhang, Wenjing Meng, Li Zhang
    Cancer Research and Treatment.2025; 57(2): 434.     CrossRef
  • Unraveling the future: Innovative design strategies and emerging challenges in HER2-targeted tyrosine kinase inhibitors for cancer therapy
    Sixiang Zheng, Ruixian Chen, Lele Zhang, Lun Tan, Lintao Li, Fangyi Long, Ting Wang
    European Journal of Medicinal Chemistry.2024; 276: 116702.     CrossRef
  • Pyrotinib combined with metronomic etoposide in heavily pretreated HER2-positive metastatic breast cancer: a single-arm, phase II study
    Jiaxuan Liu, Maiyue He, Mingxia Jiang, Shihan Zhou, Mengqi Zhang, Yiqun Li, Shanshan Chen, Ruigang Cai, Hongnan Mo, Bo Lan, Fei Ma, Binghe Xu, Qiao Li
    BMC Cancer.2024;[Epub]     CrossRef
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Review Article
Recent Developments in the Therapeutic Landscape of Advanced or Metastatic Hormone Receptor–Positive Breast Cancer
Eunice Yoojin Lee, Dae-Won Lee, Kyung-Hun Lee, Seock-Ah Im
Cancer Res Treat. 2023;55(4):1065-1076.   Published online October 5, 2023
DOI: https://doi.org/10.4143/crt.2023.846
AbstractAbstract PDFPubReaderePub
Hormone receptor–positive (HR+) disease is the most frequently diagnosed subtype of breast cancer. Among tumor subtypes, natural course of HR+ breast cancer is indolent with favorable prognosis compared to other subtypes such as human epidermal growth factor protein 2–positive disease and triple-negative disease. HR+ tumors are dependent on steroid hormone signaling and endocrine therapy is the main treatment option. Recently, the discovery of cyclin-dependent kinase 4/6 inhibitors and their synergistic effects with endocrine therapy has dramatically improved treatment outcome of advanced HR+ breast cancer. The demonstrated efficacy of additional nonhormonal agents, such as targeted therapy against mammalian target of rapamycin and phosphatidylinositol 3-kinase signaling, poly(ADP-ribose) polymerase inhibitors, antibody-drug conjugates, and immunotherapeutic agents have further expanded the available therapeutic options. This article reviews the latest advancements in the treatment of HR+ breast cancer, and in doing so discusses not only the development of currently available treatment regimens but also emerging therapies that invite future research opportunities in the field.

Citations

Citations to this article as recorded by  
  • Breast Cancer and Tumor Microenvironment: The Crucial Role of Immune Cells
    Tânia Moura, Paula Laranjeira, Olga Caramelo, Ana M. Gil, Artur Paiva
    Current Oncology.2025; 32(3): 143.     CrossRef
  • Metastasiertes hormonrezeptorpositives Mammakarzinom – die Qual der Wahl
    Marion T. van Mackelenbergh, Michael Friedrich, Nicolai Maass
    Die Gynäkologie.2025;[Epub]     CrossRef
  • Therapies for the Treatment of Advanced/Metastatic Estrogen Receptor-Positive Breast Cancer: Current Situation and Future Directions
    Rohan Kalyan Rej, Joyeeta Roy, Srinivasa Rao Allu
    Cancers.2024; 16(3): 552.     CrossRef
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  • 248 Download
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Original Article
Breast cancer
Short-term Impact of Hormone Replacement Therapy on Risk of Breast Cancer in BRCA Mutation Carriers: A Nationwide Study in South Korea
Hye Yeon Kim, Jisoo Park, Seok Joo Moon, Sohyeon Jeong, Jin Hwa Hong, Jae Kwan Lee, Geum Joon Cho, Hyun-Woong Cho
Cancer Res Treat. 2024;56(1):143-148.   Published online August 16, 2023
DOI: https://doi.org/10.4143/crt.2023.653
AbstractAbstract PDFPubReaderePub
Purpose
BRCA1/2 mutations are well-known risk factors for breast and ovarian cancers in women. Risk-reducing salpingo-oophorectomy (RRSO) is the standard treatment for preventing ovarian cancer with BRCA mutations. Postmenopausal syndrome (symptoms after RRSO can be alleviated by hormone replacement therapy (HRT); however, the use of HRT in carriers of BRCA mutations has been controversial because of the concern that HRT increases the risk of breast cancer. This study aimed to evaluate the effects of HRT in BRCA mutation carriers who underwent RRSO.
Materials and Methods
A total of 151 carriers, who underwent RRSO between 2013 and 2020 after the diagnosis of BRCA1 or BRCA2 mutations were selected and followed up for a median of 3.03 years. Patients were divided into two groups: those who received HRT after RRSO (n=33) and those who did not (n=118). We compared the incidence of breast cancer over time between these two groups.
Results
There was no significant difference in the incidence of breast cancer between women who received HRT and those who did not (p=0.229). Multivariate logistic regression analysis, adjusted for age and parity revealed no significant difference in the risk of breast cancer between these two groups (hazard ratio, 0.312; 95% confidence interval, 0.039 to 2.480; p=0.278).
Conclusion
In this study, we found no relationship between post-RRSO HRT and breast cancer in the population with BRCA mutations. Therefore, healthcare providers may consider the alleviation of symptoms of postmenopausal syndrome through HRT in patients who underwent RRSO.

Citations

Citations to this article as recorded by  
  • A contemporary review of breast cancer risk factors and the role of artificial intelligence
    Orietta Nicolis, Denisse De Los Angeles, Carla Taramasco
    Frontiers in Oncology.2024;[Epub]     CrossRef
  • 3,658 View
  • 259 Download
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