1Department of Family Medicine, Supportive Care Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
2Department of Clinical Research Design and Evaluation, Samsung Advanced Institute for Health Sciences and Technology (SAIHST), Sungkyunkwan University, Seoul, Korea
3Department of Digital Health, Samsung Advanced Institute for Health Sciences and Technology (SAIHST), Sungkyunkwan University, Seoul, Korea
4Department of Thoracic and Cardiovascular Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
5Healthcare System Gangnan Center, Seoul National University Hospital, Seoul, Korea
6Cancer Education Center, Samsung Medical Center, Seoul, Korea
7Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, Korea
8Departments of Health, Behavior, and Society and Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
9Department of Thoracic and Cardiovascular Surgery, Armed Forces Capital Hospital, Seongnam, Korea
Copyright © 2021 by the Korean Cancer Association
This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Ethical Statement
The study was approved by Institutional Review Board (IRB) of that Samsung Medical Center and informed consent were waived as we used di-identified data only (IRB no. SMC 2019-01-159-001).
Author Contributions
Concept and design: Shin DW, Cho JH, Zo JI, Cho J, Lee G, Shim YM.
Acquisition of data: Cho JH, Lee G, Shin S, Kim HK, Choi YS, Kim J, Zo JI, Shim YM.
Analysis and interpretation of data: Shin DW, Cho JH, Yoo JE, Cho J, Yoon DW, Shin S, Kim HK, Choi YS, Kim J, Zo JI, Shim YM.
Drafting the manuscript; Shin DW, Yoo JE, Lee G.
Critical revision of the manuscript for important intellectual contents: Shin DW, Cho JH, Yoo JE, Cho J, Yoon DW, Lee G, Shin S, Kim HK, Choi YS, Kim J, Zo JI, Shim YM.
Statistical analysis: Shin DW, Yoo JE, Cho J.
Obtained funding: Shin DW, Shim YM.
Administrative, technical, or material support: Lee G, Shim YM.
Integrity of the data and the accuracy of the data analysis: Shim YM.
Conflicts of Interest
Conflict of interest relevant to this article was not reported.
Cardiovascular disease includes a history of ischemic heart disease, heart failure, and cerebrovascular disease. Lung disease includes a history of chronic pulmonary obstructive disease, asthma, and diffuse interstitial lung disease. Numbers of each category might not sum up to the total number due to missing information: n=7,288 for smoking, n=8,592 for FEV1, n=6,173 for DLCO. DLCO, single-breath carbon monoxide diffusion capacity; FEV1, forced expiratory volume in 1 second; ICD-O-3, International Classification of Diseases for Oncology, 3rd edition; SD, standard deviation.
Recurrence-free survival (%)a) | Overall survival (%) | Overall relative survival (%) | ||||
---|---|---|---|---|---|---|
|
|
|
||||
5 Years (95% CI) | 10 Years (95% CI) | 5 Years (95% CI) | 10 Years (95% CI) | 5 Years (95% CI) | 10 Years (95% CI) | |
Total | 65.5 (64.3–66.8) | 58.8 (57.0–60.5) | 72.7 (71.6–73.7) | 56.7 (55.2–58.1) | 79 (78.8–79.1) | 67.8 (67.6–68.0) |
|
||||||
Age (yr) | ||||||
|
||||||
20–49 | 70.1 (66.5–73.5) | 68.6 (64.8–72.1) | 85.7 (83.0–88.0) | 76.5 (72.8–79.9) | 88.3 (88.2–88.4) | 81.4 (81.2–81.5) |
|
||||||
50–59 | 69.3 (67.0–71.5) | 63.2 (60.1–66.2) | 82.4 (80.6–84.0) | 70.6 (67.9–73.1) | 84.4 (84.3–84.4) | 75.4 (75.4–75.5) |
|
||||||
60–64 | 68.5 (65.7–71.2) | 61.9 (58.0–65.6) | 75.1 (72.7–77.3) | 61.5 (58.2–64.7) | 80.3 (80.2–80.3) | 69.5 (69.4–69.6) |
|
||||||
65–69 | 63.4 (60.5–66.2) | 53.6 (49.0–57.9) | 66.6 (64.0–69.0) | 46.1 (42.7–49.5) | 74.3 (74.2–74.3) | 61.1 (60.9–61.2) |
|
||||||
≥ 70 | 56.0 (52.8–59.0) | 42.0 (35.1–48.7) | 57.9 (55.5–60.4) | 33.2 (29.8–36.7) | 71.2 (71.1–71.3) | 56.9 (56.8–57.1) |
|
||||||
Sex | ||||||
|
||||||
Male | 63.3 (61.8–64.9) | 57.3 (55.2–59.3) | 66.1 (64.8–67.4) | 50.1 (48.3–51.8) | 78.3 (78.2–78.5) | 66.9 (66.7–67.1) |
|
||||||
Female | 69.3 (67.1–71.5) | 61.1 (57.7–64.3) | 85.6 (84.1–87.0) | 70.6 (68.0–73.1) | 80.2 (80.0–80.4) | 69.6 (69.3–69.9) |
|
||||||
Histology (ICD-O-3) | ||||||
|
||||||
Adenocarcinoma | 66.4 (64.8–68.0) | 58.2 (55.6–60.7) | 80.0 (78.7–81.2) | 63.7 (61.6–65.7) | 79.7 (79.5–79.9) | 68.9 (68.7–69.1) |
|
||||||
Squamous cell carcinoma | 62.6 (60.2–64.9) | 56.8 (53.7–59.7) | 59.1 (57.0–61.1) | 43.3 (40.9–45.7) | 76.9 (76.7–77.2) | 64.9 (64.6–65.3) |
|
||||||
Large cell carcinoma | 49.3 (41.7–56.5) | 43.6 (35.0–51.9) | 47.8 (40.6–54.6) | 36.8 (29.6–44.0) | 77.9 (77.1–78.7) | 66.3 (65.1–67.4) |
|
||||||
Others/Mixed | 70.5 (66.1–74.5) | 67.3 (62.4–71.7) | 74.4 (70.5–78.0) | 63.5 (58.7–68.0) | 80.9 (80.3–81.5) | 70.7 (69.8–71.5) |
|
||||||
Stage at diagnosis | ||||||
|
||||||
I | 78.2 (76.7–79.6) | 71.2 (69.0–73.4) | 84.5 (83.4–85.6) | 69.6 (67.8–71.4) | 79.3 (79.1–79.4) | 68.3 (68.0–68.5) |
|
||||||
II | 50.6 (47.8–53.2) | 43.9 (40.4–47.4) | 58.0 (55.6–60.4) | 41.7 (38.8–44.5) | 78.3 (78.0–78.5) | 66.8 (66.4–67.2) |
|
||||||
III | 31.3 (28.0–34.5) | 26.5 (23.0–30.1) | 45.0 (41.8–47.9) | 27.4 (24.1–30.8) | 78.7 (78.3–79.1) | 67.5 (67.0–68.0) |
|
||||||
Year of diagnosis | ||||||
|
||||||
1994–1999 | 51.5 (46.7–56.1) | 46.7 (41.8–51.5) | 53.5 (49.0–57.8) | 39.03 (34.7–43.3) | 80.0 (79.5–80.5) | 69.3 (68.6–70.1) |
|
||||||
2000–2009 | 63.3 (61.4–65.2) | 56.6 (54.3–58.3) | 68.1 (66.4–69.8) | 53.7 (51.8–55.6) | 79.1 (78.9–79.3) | 68.0 (67.7–68.4) |
|
||||||
2010–2016 | 68.5 (66.6–70.3) | 78.0 (76.6–79.3) | 78.8 (78.6–79.0) | 67.6 (67.4–67.8) | ||
|
||||||
Smoking status | ||||||
|
||||||
Never smoker | 69.3 (67.2–71.3) | 60.9 (57.6–63.9) | 84.6 (83.1–86.0) | 70.3 (67.8–72.7) | 88.9 (88.8–88.9) | 77.9 (77.8–80.0) |
|
||||||
Ex-smoker | 62.9 (60.4–65.2) | 57.5 (54.0–60.8) | 66.2 (64.0–68.3) | 49.6 (46.6–52.5) | 74.6 (74.3–75.0) | 62.7 (62.2–63.2) |
|
||||||
Current smoker | 64.2 (61.7–66.7) | 58.5 (55.1–61.8) | 67.8 (65.6–69.9) | 50.8 (47.7–53.7) | 73.7 (73.3–74.0) | 61.5 (61.0–62.0) |
|
||||||
Comorbidities | ||||||
|
||||||
Hypertension | ||||||
|
||||||
No | 65.3 (63.8–66.8) | 58.5 (56.4–60.5) | 72.5 (71.2–73.8) | 57.8 (56.0–59.5) | 78.0 (77.8–78.2) | 67.5 (67.3–67.8) |
|
||||||
Yes | 66.0 (63.7–68.2) | 59.5 (56.2–62.7) | 73.1 (71.2–74.9) | 53.8 (51.0–56.6) | 80.6 (80.5–80.8) | 68.1 (67.9–68.4) |
|
||||||
Diabetes mellitus | ||||||
|
||||||
No | 65.8 (64.4–67.1) | 58.8 (56.9–60.6) | 73.9 (72.7–75.0) | 57.9 (56.3–59.5) | 79.9 (79.8–80.0) | 69.3 (69.1–69.4) |
|
||||||
Yes | 64.1 (60.5–67.4) | 59.2 (54.5–63.6) | 65.7 (62.6–68.6) | 48.9 (44.8–52.9) | 73.9 (73.4–74.3) | 59.8 (59.2–60.5) |
|
||||||
CVD | ||||||
|
||||||
No | 65.6 (64.3–66.9) | 58.9 (57.1–60.7) | 73.4 (72.3–74.4) | 57.6 (56.0–59.1) | 79.5 (79.3–79.6) | 68.5 (68.3–68.7) |
|
||||||
Yes | 64.3 (59.5–68.8) | 56.7 (48.2–64.2) | 65.7 (61.7–69.3) | 45.2 (39.1–51.1) | 74.4 (74.1–74.7) | 61.6 (61.2–62.0) |
|
||||||
Lung disease | ||||||
|
||||||
No | 65.9 (64.6–67.2) | 59.1 (57.2–60.8) | 74.0 (72.9–75.0) | 58.0 (56.5–59.5) | 80.2 (80.1–80.3) | 69.4 (69.2–69.6) |
|
||||||
Yes | 59.4 (54.0–64.4) | 55.9 (49.3–62.0) | 55.1 (50.4–59.5) | 36.1 (30.0–42.2) | 63.7 (62.9–64.5) | 45.8 (44.8–46.9) |
|
||||||
Preoperative pulmonary function | ||||||
|
||||||
FEV1 < 80% of predicted | ||||||
|
||||||
No | 66.2 (64.8–67.6) | 59.6 (57.7–61.5) | 74.9 (73.8–76.1) | 59.5 (57.9–61.1) | 81.1 (80.9–81.2) | 70.6 (70.4–70.8) |
|
||||||
Yes | 61.3 (58.2–64.4) | 53.8 (49.0–58.3) | 62.3 (59.5–64.9) | 80.3 (78.9–81.6) | 69.3 (69.1–69.6) | 54.2 (53.8–54.6) |
|
||||||
DLCO < 80% of predicted | ||||||
|
||||||
No | 69.5 (67.7–71.3) | 60.9 (56.8–64.7) | 80.3 (78.9–81.6) | 62.3 (59.2–65.2) | 86.5 (86.4–86.7) | 74.5 (74.2–74.7) |
|
||||||
Yes | 58.7 (54.2–62.9) | 54.8 (48.5–60.6) | 41.1 (34.1–48.0) | 41.1 (34.1–48.0) | 67.9 (67.3–68.5) | 53.5 (52.7–54.3) |
Characteristics of study population at the time of surgery
Characteristic | No. (%) |
---|---|
Age (yr) | |
Mean±SD | 61.7±9.8 |
20–49 | 918 (10.4) |
50–59 | 2,428 (27.6) |
60–64 | 1,718 (19.5) |
65–69 | 1,673 (19.0) |
≥ 70 | 2,061 (23.4) |
Sex | |
Male | 5,732 (65.2) |
Female | 3,066 (34.8) |
Year of diagnosis | |
1994–1999 | 497 (5.6) |
2000–2009 | 2,815 (32.0) |
2010–2016 | 5,486 (62.4) |
Smokinga) | |
Never smoker | 2,975 (40.8) |
Ex-smoker | 2,249 (30.9) |
Current smoker | 2,064 (28.3) |
Comorbidities | |
Hypertension | 2,905 (33.0) |
Diabetes mellitus | 1,282 (14.6) |
Cardiovascular disease | 809 (9.2) |
Lung disease | 623 (7.1) |
Histology (ICD-O-3) | |
Adenocarcinoma | 5,536 (62.9) |
Squamous cell carcinoma | 2,475 (28.1) |
Large cell carcinoma | 210 (2.4) |
Others/Mixed | 577 (6.6) |
Pathologic stage | |
I | 5,617 (63.8) |
II | 1,943 (22.1) |
III | 1,238 (14.1) |
Surgical approach | |
VATS | 4,202 (47.8) |
Open | 4,596 (52.2) |
Surgical procedure | |
Pneumonectomy | 471 (5.4) |
Bilobectomy | 448 (5.1) |
Lobectomy | 6,856 (77.9) |
Segmentectomy | 406 (4.6) |
Wedge resection | 617 (7.0) |
Preoperative pulmonary functiona) | |
FEV1 (%), mean±SD | 94.4±18.5 |
FEV1 < 80% of predicted | 1,652 (19.2) |
DLCO (%), mean±SD | 90.9±18.7 |
DLCO < 80% of predicted | 1,609 (26.1) |
Cardiovascular disease includes a history of ischemic heart disease, heart failure, and cerebrovascular disease. Lung disease includes a history of chronic pulmonary obstructive disease, asthma, and diffuse interstitial lung disease. Numbers of each category might not sum up to the total number due to missing information: n=7,288 for smoking, n=8,592 for FEV1, n=6,173 for DLCO. DLCO, single-breath carbon monoxide diffusion capacity; FEV1, forced expiratory volume in 1 second; ICD-O-3, International Classification of Diseases for Oncology, 3rd edition; SD, standard deviation.
Five- and 10-year recurrence-free, overall, and overall relative survival of lung cancer patients
Recurrence-free survival (%) |
Overall survival (%) | Overall relative survival (%) | ||||
---|---|---|---|---|---|---|
|
|
| ||||
5 Years (95% CI) | 10 Years (95% CI) | 5 Years (95% CI) | 10 Years (95% CI) | 5 Years (95% CI) | 10 Years (95% CI) | |
Total | 65.5 (64.3–66.8) | 58.8 (57.0–60.5) | 72.7 (71.6–73.7) | 56.7 (55.2–58.1) | 79 (78.8–79.1) | 67.8 (67.6–68.0) |
| ||||||
Age (yr) | ||||||
| ||||||
20–49 | 70.1 (66.5–73.5) | 68.6 (64.8–72.1) | 85.7 (83.0–88.0) | 76.5 (72.8–79.9) | 88.3 (88.2–88.4) | 81.4 (81.2–81.5) |
| ||||||
50–59 | 69.3 (67.0–71.5) | 63.2 (60.1–66.2) | 82.4 (80.6–84.0) | 70.6 (67.9–73.1) | 84.4 (84.3–84.4) | 75.4 (75.4–75.5) |
| ||||||
60–64 | 68.5 (65.7–71.2) | 61.9 (58.0–65.6) | 75.1 (72.7–77.3) | 61.5 (58.2–64.7) | 80.3 (80.2–80.3) | 69.5 (69.4–69.6) |
| ||||||
65–69 | 63.4 (60.5–66.2) | 53.6 (49.0–57.9) | 66.6 (64.0–69.0) | 46.1 (42.7–49.5) | 74.3 (74.2–74.3) | 61.1 (60.9–61.2) |
| ||||||
≥ 70 | 56.0 (52.8–59.0) | 42.0 (35.1–48.7) | 57.9 (55.5–60.4) | 33.2 (29.8–36.7) | 71.2 (71.1–71.3) | 56.9 (56.8–57.1) |
| ||||||
Sex | ||||||
| ||||||
Male | 63.3 (61.8–64.9) | 57.3 (55.2–59.3) | 66.1 (64.8–67.4) | 50.1 (48.3–51.8) | 78.3 (78.2–78.5) | 66.9 (66.7–67.1) |
| ||||||
Female | 69.3 (67.1–71.5) | 61.1 (57.7–64.3) | 85.6 (84.1–87.0) | 70.6 (68.0–73.1) | 80.2 (80.0–80.4) | 69.6 (69.3–69.9) |
| ||||||
Histology (ICD-O-3) | ||||||
| ||||||
Adenocarcinoma | 66.4 (64.8–68.0) | 58.2 (55.6–60.7) | 80.0 (78.7–81.2) | 63.7 (61.6–65.7) | 79.7 (79.5–79.9) | 68.9 (68.7–69.1) |
| ||||||
Squamous cell carcinoma | 62.6 (60.2–64.9) | 56.8 (53.7–59.7) | 59.1 (57.0–61.1) | 43.3 (40.9–45.7) | 76.9 (76.7–77.2) | 64.9 (64.6–65.3) |
| ||||||
Large cell carcinoma | 49.3 (41.7–56.5) | 43.6 (35.0–51.9) | 47.8 (40.6–54.6) | 36.8 (29.6–44.0) | 77.9 (77.1–78.7) | 66.3 (65.1–67.4) |
| ||||||
Others/Mixed | 70.5 (66.1–74.5) | 67.3 (62.4–71.7) | 74.4 (70.5–78.0) | 63.5 (58.7–68.0) | 80.9 (80.3–81.5) | 70.7 (69.8–71.5) |
| ||||||
Stage at diagnosis | ||||||
| ||||||
I | 78.2 (76.7–79.6) | 71.2 (69.0–73.4) | 84.5 (83.4–85.6) | 69.6 (67.8–71.4) | 79.3 (79.1–79.4) | 68.3 (68.0–68.5) |
| ||||||
II | 50.6 (47.8–53.2) | 43.9 (40.4–47.4) | 58.0 (55.6–60.4) | 41.7 (38.8–44.5) | 78.3 (78.0–78.5) | 66.8 (66.4–67.2) |
| ||||||
III | 31.3 (28.0–34.5) | 26.5 (23.0–30.1) | 45.0 (41.8–47.9) | 27.4 (24.1–30.8) | 78.7 (78.3–79.1) | 67.5 (67.0–68.0) |
| ||||||
Year of diagnosis | ||||||
| ||||||
1994–1999 | 51.5 (46.7–56.1) | 46.7 (41.8–51.5) | 53.5 (49.0–57.8) | 39.03 (34.7–43.3) | 80.0 (79.5–80.5) | 69.3 (68.6–70.1) |
| ||||||
2000–2009 | 63.3 (61.4–65.2) | 56.6 (54.3–58.3) | 68.1 (66.4–69.8) | 53.7 (51.8–55.6) | 79.1 (78.9–79.3) | 68.0 (67.7–68.4) |
| ||||||
2010–2016 | 68.5 (66.6–70.3) | 78.0 (76.6–79.3) | 78.8 (78.6–79.0) | 67.6 (67.4–67.8) | ||
| ||||||
Smoking status | ||||||
| ||||||
Never smoker | 69.3 (67.2–71.3) | 60.9 (57.6–63.9) | 84.6 (83.1–86.0) | 70.3 (67.8–72.7) | 88.9 (88.8–88.9) | 77.9 (77.8–80.0) |
| ||||||
Ex-smoker | 62.9 (60.4–65.2) | 57.5 (54.0–60.8) | 66.2 (64.0–68.3) | 49.6 (46.6–52.5) | 74.6 (74.3–75.0) | 62.7 (62.2–63.2) |
| ||||||
Current smoker | 64.2 (61.7–66.7) | 58.5 (55.1–61.8) | 67.8 (65.6–69.9) | 50.8 (47.7–53.7) | 73.7 (73.3–74.0) | 61.5 (61.0–62.0) |
| ||||||
Comorbidities | ||||||
| ||||||
Hypertension | ||||||
| ||||||
No | 65.3 (63.8–66.8) | 58.5 (56.4–60.5) | 72.5 (71.2–73.8) | 57.8 (56.0–59.5) | 78.0 (77.8–78.2) | 67.5 (67.3–67.8) |
| ||||||
Yes | 66.0 (63.7–68.2) | 59.5 (56.2–62.7) | 73.1 (71.2–74.9) | 53.8 (51.0–56.6) | 80.6 (80.5–80.8) | 68.1 (67.9–68.4) |
| ||||||
Diabetes mellitus | ||||||
| ||||||
No | 65.8 (64.4–67.1) | 58.8 (56.9–60.6) | 73.9 (72.7–75.0) | 57.9 (56.3–59.5) | 79.9 (79.8–80.0) | 69.3 (69.1–69.4) |
| ||||||
Yes | 64.1 (60.5–67.4) | 59.2 (54.5–63.6) | 65.7 (62.6–68.6) | 48.9 (44.8–52.9) | 73.9 (73.4–74.3) | 59.8 (59.2–60.5) |
| ||||||
CVD | ||||||
| ||||||
No | 65.6 (64.3–66.9) | 58.9 (57.1–60.7) | 73.4 (72.3–74.4) | 57.6 (56.0–59.1) | 79.5 (79.3–79.6) | 68.5 (68.3–68.7) |
| ||||||
Yes | 64.3 (59.5–68.8) | 56.7 (48.2–64.2) | 65.7 (61.7–69.3) | 45.2 (39.1–51.1) | 74.4 (74.1–74.7) | 61.6 (61.2–62.0) |
| ||||||
Lung disease | ||||||
| ||||||
No | 65.9 (64.6–67.2) | 59.1 (57.2–60.8) | 74.0 (72.9–75.0) | 58.0 (56.5–59.5) | 80.2 (80.1–80.3) | 69.4 (69.2–69.6) |
| ||||||
Yes | 59.4 (54.0–64.4) | 55.9 (49.3–62.0) | 55.1 (50.4–59.5) | 36.1 (30.0–42.2) | 63.7 (62.9–64.5) | 45.8 (44.8–46.9) |
| ||||||
Preoperative pulmonary function | ||||||
| ||||||
FEV1 < 80% of predicted | ||||||
| ||||||
No | 66.2 (64.8–67.6) | 59.6 (57.7–61.5) | 74.9 (73.8–76.1) | 59.5 (57.9–61.1) | 81.1 (80.9–81.2) | 70.6 (70.4–70.8) |
| ||||||
Yes | 61.3 (58.2–64.4) | 53.8 (49.0–58.3) | 62.3 (59.5–64.9) | 80.3 (78.9–81.6) | 69.3 (69.1–69.6) | 54.2 (53.8–54.6) |
| ||||||
DLCO < 80% of predicted | ||||||
| ||||||
No | 69.5 (67.7–71.3) | 60.9 (56.8–64.7) | 80.3 (78.9–81.6) | 62.3 (59.2–65.2) | 86.5 (86.4–86.7) | 74.5 (74.2–74.7) |
| ||||||
Yes | 58.7 (54.2–62.9) | 54.8 (48.5–60.6) | 41.1 (34.1–48.0) | 41.1 (34.1–48.0) | 67.9 (67.3–68.5) | 53.5 (52.7–54.3) |
CI, confidence interval; CVD, cardiovascular disease; DLCO, single-breath carbon monoxide diffusion capacity; FEV1, forced expiratory volume in 1 second; ICD-O-3, International Classification of Diseases for Oncology, 3rd edition.
a)Events for RFS included recurrence only and deaths were censored.
Cardiovascular disease includes a history of ischemic heart disease, heart failure, and cerebrovascular disease. Lung disease includes a history of chronic pulmonary obstructive disease, asthma, and diffuse interstitial lung disease. Numbers of each category might not sum up to the total number due to missing information: n=7,288 for smoking, n=8,592 for FEV1, n=6,173 for DLCO. DLCO, single-breath carbon monoxide diffusion capacity; FEV1, forced expiratory volume in 1 second; ICD-O-3, International Classification of Diseases for Oncology, 3rd edition; SD, standard deviation.
CI, confidence interval; CVD, cardiovascular disease; DLCO, single-breath carbon monoxide diffusion capacity; FEV1, forced expiratory volume in 1 second; ICD-O-3, International Classification of Diseases for Oncology, 3rd edition. Events for RFS included recurrence only and deaths were censored.