This study aimed to determine the incidence of male breast cancer (MBC) and its survival outcomes in Korea, and to compare these results to those for female breast cancer (FBC).
We searched the Korea Central Cancer Registry and identified 227,122 breast cancer cases that were diagnosed between 1999 and 2016. Demographic and clinical characteristics and overall survival (OS) rates were estimated according to sex, age, histological type, and cancer stage.
The 227,122 patients included 1,094 MBC cases and 226,028 FBC cases. Based on the age-standardized rate, the male: female ratio was 0.0055:1. The most common ages at diagnosis were 60-69 years for MBC and 40-49 years for FBC (p < 0.001). Male patients were less likely than female patients to receive adjuvant radiotherapy (7.5% vs. 21.8%, p < 0.001) or adjuvant chemotherapy (40.1% vs. 55.4%, p < 0.001). The 5-year OS rates after diagnosis were 88.8% for all patients, although it was significantly lower for MBC than for FBC (76.2% vs. 88.9%, p < 0.001). In both groups, older age (≥ 60 years) was associated with shorter survival. The 5-year OS rates for the invasive histological types were 75.8% for men and 89.0% for women. The 5-year OS rates in both groups decreased with increasing cancer stage.
MBC was diagnosed at older ages than FBC, and male patients were less likely to receive radiotherapy and chemotherapy. The survival outcomes were worse for MBC than for FBC, with even poorer outcomes related to older age, the inflammatory histological types, and advanced stage. It is important that clinicians recognize the differences between FBC and MBC when treating these patients.
Male breast cancer (MBC) is a very rare disease [
The KCCR was searched to identify all patients with breast cancer who were diagnosed between 1999 and 2016. Primary breast cancer (C50) was defined according to the International Classification of Diseases, 10th edition (ICD-10) [
Patients were grouped according to sex, age (< 40 years, 40-49 years, 50-59 years, 60-69 years, 70-79 years, and ≥ 80 years), the Surveillance, Epidemiology, and End Results (SEER) summary stage, and the first course of treatment within 4 months after the diagnosis. Histological types were first classified according to the ICD-10 [
Analysis of variance testing was used to evaluate continuous variables, and the chi-squared test was used to evaluate categorical variables. Survival curves were created using the Kaplan-Meier method [
The study protocol was approved by our institutional review board (NCC 2018-0224) and the requirement for informed consent was waived because it is secondary analysis of de-identified data.
Between 1999 and 2016, the KCCR included 227,122 patients with newly diagnosed breast cancer, including 1,094 MBC patients and 226,028 FBC patients. Based on the ASR, the male:female ratio was 0.0055. Since 1999, the overall number of patients diagnosed with breast cancer has steadily increased, although different patterns were observed according to sex, with the annual percent change being –0.69% for MBC (p=0.397) and +5.61% for FBC (p < 0.001) (
The 5-year OS rates after diagnosis were 88.8% for all patients, 76.2% for male patients, and 88.9% for female patients (p < 0.001). The 10-year OS rates were 81.6% for all patients, 60.1% for male patients, and 81.7% for female patients (
The univariate analyses revealed that mortality was significantly associated with male sex (p < 0.001), older age (p < 0.001), the inflammatory histological types (p < 0.001), and advanced cancer stage (p < 0.001). The multivariate analyses also revealed that mortality was independently associated with male sex (hazard ratio [HR], 1.68; 95% confidence interval [CI], 1.45 to 1.96; p < 0.001), age of ≥ 60 years (HR, 2.19; 95% CI, 2.09 to 2.30; p < 0.001), the inflammatory histological types (HR, 2.93; 95% CI, 2.22 to 3.87; p < 0.001), and especially distant metastasis (HR, 22.05; 95% CI, 21.16 to 22.98; p < 0.001) (
The present study revealed that, based on KCCR data from an 18-year period, MBC accounted for 0.48% of all newly diagnosed breast cancers in Korea, with a slightly decreasing trend each year since 1999. In this context, MBC is known to be a rare disease, accounting for approximately 0.6%-1% of newly diagnosed breast cancer cases in Western countries [
Relative to FBC, adjuvant radiotherapy is less commonly performed for MBC patients [
This study also found that adjuvant chemotherapy was used significantly less frequently in MBC overall, and within each stage (
Improvements in early detection and treatment strategies have improved the survival rate for breast cancer. For example, KCCR data from 2002-2013 revealed that the 5-year relative survival rates were 87% for men and 90.8% for women [
This study had several strengths, such as the use of a population-based cancer registry that contained information regarding approximately 98% of Korean cancer cases [
When comparing OS rates, we divided the histological type into four groups because of differences in treatment and prognosis. In this study, we were defined as an invasive type, which accounts for the majority, and the limitation was that the group was not compared for each type.
In conclusion, the present study revealed noticeable differences between MBC and FBC cases, with MBC having an older peak age at diagnosis. In addition, MBC had poorer survival outcomes than FBC, and we observed different OS rates patterns according to age, histological type, and cancer stage. Therefore, clinicians need to recognize the differences between FBC and MBC when treating these patients, and additional studies are needed to develop specific treatment guidelines for MBC.
Supplementary materials are available at Cancer Research and Treatment website (
The status of adjuvant radiotherapy according to disease stage
The status of adjuvant chemotherapy according to disease stage
Conflict of interest relevant to this article was not reported.
This work was supported by National Cancer Center Grants (NCC-1911274-1 and NCC-1910132-1).
Overall survival among all Korean breast cancer patients (A) and according to sex (B).
Overall survival according to sex, age, histological type, and breast cancer stage. (A) Overall survival was evaluated for male patients who were < 40 years old (blue line), men who were 40-59 years old (red line), men who were ≥ 60 years old (green line), female patients who were < 40 years old (orange line), women who were 40-59 years old (gray line), and women who were ≥ 60 years old (purple line). (B) Overall survival was also evaluated for male patients with invasive carcinoma (blue line), Paget disease (red line), inflammatory type (green line), and other cancer types (orange line), as well as for female patients with invasive carcinoma (gray line), Paget disease (purple line), inflammatory type (pink line), and other cancer types (light green line). (C) Overall survival was also evaluated for male patients with localized breast cancer (blue line), regional breast cancer (red line), distant breast cancer (green line), and unknown breast cancer (orange line), as well as for female patients with localized breast cancer (gray line), regional breast cancer (purple line), distant breast cancer (pink line), and unknown breast cancer (light green line).
Age-standardized rates of breast cancer among men and women according to year
Year | Diagnosis of breast cancer patients |
|||||
---|---|---|---|---|---|---|
Male |
Female |
Male/Female ratio (ASR) | Male/Female ratio (cases) | |||
ASR | No. | ASR | No. | |||
1999 | 0.17 | 39 | 20.69 | 5,640 | 0.0082 | 0.0065 |
2000 | 0.23 | 57 | 20.67 | 5,782 | 0.0126 | 0.0084 |
2001 | 0.22 | 49 | 24.44 | 7,032 | 0.0090 | 0.0063 |
2002 | 0.25 | 56 | 26.88 | 7,936 | 0.0093 | 0.0066 |
2003 | 0.23 | 57 | 27.58 | 8,373 | 0.0083 | 0.0055 |
2004 | 0.21 | 51 | 29.06 | 9,064 | 0.0072 | 0.0056 |
2005 | 0.21 | 55 | 31.83 | 10,124 | 0.0066 | 0.0054 |
2006 | 0.19 | 50 | 33.11 | 10,812 | 0.0056 | 0.0046 |
2007 | 0.13 | 35 | 35.40 | 11,855 | 0.0036 | 0.0030 |
2008 | 0.26 | 75 | 37.08 | 12,693 | 0.0071 | 0.0056 |
2009 | 0.20 | 61 | 38.56 | 13,502 | 0.0051 | 0.0044 |
2010 | 0.21 | 69 | 40.53 | 14,481 | 0.0051 | 0.0047 |
2011 | 0.22 | 72 | 43.88 | 15,976 | 0.0049 | 0.0045 |
2012 | 0.18 | 65 | 44.79 | 16,562 | 0.0040 | 0.0038 |
2013 | 0.16 | 58 | 45.79 | 17,274 | 0.0035 | 0.0034 |
2014 | 0.21 | 77 | 47.45 | 18,236 | 0.0044 | 0.0042 |
2015 | 0.20 | 77 | 48.99 | 19,076 | 0.0040 | 0.0040 |
2016 | 0.22 | 91 | 54.60 | 21,610 | 0.0040 | 0.0042 |
Total | 0.20 | 1,094 | 37.38 | 226,028 | 0.0055 | 0.0047 |
APC | –0.69% (p=0.397) | 5.61% (p < 0.001) |
ASR, age-standardized rate (world standard population); APC, annual percent change.
Clinicopathological characteristics of breast cancer patients in Korea
Characteristic | Men | Women | p-value |
---|---|---|---|
1,094 | 226,028 | ||
Mean±SD | 61.71±13.97 | 50.82±11.49 | < 0.001 |
Median (range) | 63 (24-97) | 49 (6-102) | |
< 0.001 | |||
< 40 | 69 (6.4) | 32,708 (14.5) | |
40-49 | 166 (15.2) | 83,179 (36.8) | |
50-59 | 229 (20.9) | 62,335 (27.6) | |
60-69 | 272 (24.9) | 30,882 (13.7) | |
70-79 | 257 (23.5) | 13,385 (5.9) | |
≥ 80 | 101 (9.2) | 3,539 (1.6) | |
< 0.001 | |||
Invasive | 1,061 (97.0) | 223,561 (98.9) | |
Paget | 14 (1.3) | 1,288 (0.6) | |
Inflammatory | 1 (0.1) | 201 (0.1) | |
Others | 18 (1.6) | 978 (0.4) | |
730 | 172,077 | < 0.001 | |
Localized | 322 (44.1) | 95,017 (55.2) | |
Regional | 284 (38.9) | 58,371 (33.9) | |
Distant | 50 (6.8) | 8,463 (4.9) | |
Unknown | 74 (10.1) | 10,226 (5.9) | |
< 0.001 | |||
Yes | 893 (81.6) | 196,516 (86.9) | |
No | 201 (18.4) | 29,512 (13.1) | |
< 0.001 | |||
Yes | 82 (7.5) | 49,367 (21.8) | |
No | 1,012 (92.5) | 177,673 (78.6) | |
< 0.001 | |||
Yes | 439 (40.1) | 125,247 (55.4) | |
No | 655 (59.9) | 100,781 (44.6) | |
Mean±SD | 75.91±58.09 | 84.11±56.68 | < 0.001 |
Median (range) | 64 (0-227) | 72 (0-227) |
Values are presented as number (%). SD, standard deviation.
ANOVA tests were performed to evaluate differences by factor for continuous variables, and chi-square tests were performed to evaluate differences by factor for categorical variables.
Univariate and multivariate Poisson regression analyses according to risk factors between 1999 and 2016
Univariate |
Multivariate |
|||||
---|---|---|---|---|---|---|
HR | 95% CI | p-value | HR | 95% CI | p-value | |
Female | 1.00 | 1.00 | ||||
Male | 2.52 | 2.27-2.80 | < 0.001 | 1.68 | 1.45-1.96 | < 0.001 |
< 40 | 1.00 | 1.00 | ||||
40-59 | 0.79 | 0.77-0.82 | < 0.001 | 0.89 | 0.85-0.93 | < 0.001 |
≥ 60 | 2.05 | 1.98-2.12 | < 0.001 | 2.19 | 2.09-2.30 | < 0.001 |
Invasive | 1.00 | 1.00 | ||||
Paget | 0.96 | 0.87-1.14 | 0.941 | 1.12 | 0.92-1.36 | 0.276 |
Inflammatory | 5.70 | 4.93-6.59 | < 0.001 | 2.93 | 2.22-3.87 | < 0.001 |
Others | 0.95 | 0.83-1.10 | 0.513 | 1.22 | 0.95-1.55 | 0.115 |
Localized | 1.00 | 1.00 | ||||
Regional | 2.78 | 2.68-2.89 | < 0.001 | 2.85 | 2.75-2.96 | < 0.001 |
Distant | 22.29 | 21.39-23.23 | < 0.001 | 22.05 | 21.16-22.98 | < 0.001 |
Unknown | 3.50 | 3.31-3.69 | < 0.001 | 3.46 | 3.28-3.65 | < 0.001 |
HR, hazard ratio; CI, confidence interval.