Retrospective Study
Copyright ©The Author(s) 2018. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Oct 28, 2018; 24(40): 4586-4595
Published online Oct 28, 2018. doi: 10.3748/wjg.v24.i40.4586
Second primary malignancy risk after radiotherapy in rectal cancer survivors
Ti-Hao Wang, Chia-Jen Liu, Tze-Fan Chao, Tzeng-Ji Chen, Yu-Wen Hu
Ti-Hao Wang, Department of Radiation Oncology, China Medical University Hospital, Taichung 40447, Taiwan
Chia-Jen Liu, Department of Medicine, Taipei Veterans General Hospital, Division of Hematology and Oncology, Taipei 11217, Taiwan
Tze-Fan Chao, Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei 11217, Taiwan
Tzeng-Ji Chen, Department of Family Medicine, Taipei Veterans General Hospital, Taipei 11217, Taiwan
Yu-Wen Hu, Department of Oncology, Taipei Veterans General Hospital, Taipei 11217, Taiwan
Yu-Wen Hu, Institute of Public Health, National Yang-Ming University, Taipei 11217, Taiwan
Author contributions: Wang TH, Liu CJ, Chao TF, Chen TJ and Hu YW designed research; Wang TH, Liu CJ and Chao TF performed research; Wang TH, Chen TJ and Hu YW contributed new reagents or analytic tools; Wang TH and Hu YW analyzed data; Wang TH wrote the paper.
Institutional review board statement: This study was exempted from full review by the Institutional Review Board (No. 2016-05-007BC).
Conflict-of-interest statement: None.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Yu-Wen Hu, MD, Attending Doctor, Department of Oncology, Taipei Veterans General Hospital, No.201, Sec. 2, Shipai Road, Beitou District, Taipei 11217, Taiwan. ywhu@vghtpe.gov.tw
Telephone: +886-2-28757270 Fax: +886-2-28732131
Received: June 30, 2018
Peer-review started: July 2, 2018
First decision: July 18, 2018
Revised: August 14, 2018
Accepted: October 5, 2018
Article in press: October 5, 2018
Published online: October 28, 2018
Abstract
AIM

To investigate second primary malignancy (SPM) risk after radiotherapy in rectal cancer survivors

METHODS

We used Taiwan’s National Health Insurance Research Database to identify rectal cancer patients between 1996 and 2011. Surgery-alone, preoperative short course, preoperative long course, and post-operative radiotherapy groups were defined. The overall and site-specific SPM incidence rates were compared among the radiotherapy groups by multivariate Cox regression, taking chemotherapy and comorbidities into account. Sensitivity tests were performed for attained-year adjustment and long-term survivors analysis.

RESULTS

A total of 28220 patients were analyzed. The 10-year cumulative SPM incidence was 7.8% [95% confidence interval (CI): 7.2%-8.2%] using a competing risk model. The most common sites of SPM were the lung, liver, and prostate. Radiotherapy was not associated with increased SPM risk in multi-variate Cox model (hazard ratio = 1.05, 95%CI: 0.91-1.21, P = 0.494). The SPM hazard remained unchanged in 10-year-survivors. In addition, no SPM risk difference was found between the preoperative radiotherapy and postoperative radiotherapy groups.

CONCLUSION

In this large population-based cohort study, we demonstrated that radiotherapy had no increase in SPM.

Keywords: Radiotherapy, Second primary malignancy, Rectal cancer, Preoperative long-course, Preoperative short-course

Core tip: Developing a second primary malignancy (SPM) after radiotherapy represents a major problem for long-term cancer survivors. In this large population-based study, no increased risk of developing SPM was found in rectal cancer patients who received pelvic radiotherapy in their initial treatment after carefully adjusted basline confounders. Also, the SPM risk remained the same among the preoperative long-course, preoperative short-course, and postoperative radiotherapy groups. However, rectal cancer survivors, similarly to other cancer survivors, are burdened with an overall higher probability of developing a second primary cancer. Life-long follow-up is recommended.