J Cancer 2020; 11(21):6204-6212. doi:10.7150/jca.44726 This issue

Research Paper

Does radiotherapy increase the risk of colorectal cancer among prostate cancer patients? A large population-based study

Chung-Han Ho1,2,3, Kuo-Chen Cheng4,5, Chien-Ming Chao6,7,8, Chih-Cheng Lai9, Shyh-Ren Chiang4,10, Chin-Ming Chen7, Kuang-Ming Liao11, Jhi-Joung Wang1,12, Po-Huang Lee13, Chao-Ming Hung14, Chi-Ming Tai15, Chong-Chi Chiu14✉

1. Department of Medical Research, Chi Mei Medical Center, Tainan 71004, Taiwan
2. Department of Hospital and Health Care Administration, Chia Nan University of Pharmacy and Science, Tainan 71710, Taiwan
3. Cancer Center, Wan Fang Hospital, Taipei Medical University, Taipei 11696, Taiwan
4. Department of Internal Medicine, Chi Mei Medical Center, Tainan 71004, Taiwan
5. Department of Safety, Health and Environment, Chung Hwa University of Medical Technology, Tainan 71703, Taiwan
6. Department of Intensive Care Medicine, Chi Mei Medical Center, Liouying 73657, Taiwan
7. Department of Intensive Care Medicine, Chi Mei Medical Center, Tainan 71004, Taiwan
8. Department of Dental Laboratory Technology, Min-Hwei College of Health Care Management, Tainan 73657, Taiwan
9. Department of Internal Medicine, Kaohsiung Veterans General Hospital, Tainan Branch, Tainan 71004, Taiwan
10. Departments of General Education, Chia Nan University of Pharmacy and Science, Tainan 71710, Taiwan
11. Department of Internal Medicine, Chi Mei Medical Center, Chiali 72263, Taiwan.
12. AI Biomed Center, Southern Taiwan University of Science and Technology, Tainan 71005, Taiwan
13. Department of Surgery, E-Da Hospital. I-Shou University, Kaohsiung 82400, Taiwan
14. Department of General Surgery, E-Da Cancer Hospital, I-Shou University, Kaohsiung 82400, Taiwan
15. Department of Internal Medicine, E-Da Hospital, I-Shou University, Kaohsiung 82400, Taiwan

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Citation:
Ho CH, Cheng KC, Chao CM, Lai CC, Chiang SR, Chen CM, Liao KM, Wang JJ, Lee PH, Hung CM, Tai CM, Chiu CC. Does radiotherapy increase the risk of colorectal cancer among prostate cancer patients? A large population-based study. J Cancer 2020; 11(21):6204-6212. doi:10.7150/jca.44726. Available from https://www.jcancer.org/v11p6204.htm

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Abstract

Objective: The survival of prostate cancer (PC) patients after radiotherapy (RT) has improved over time, but it raises the debate of increased risk of secondary colorectal cancer (SCRC). This study aimed to assess whether RT for PC treatment increases the risk of SCRC in comparison with radical prostatectomy (RP).

Methods: A population-based cohort of PC patients treated only with RT or only with RP between January 2007 and December 2015 was identified from the Taiwan Cancer Registry. The incidence rate of SCRC development was estimated using Cox regression model.

Results: In this study, total 8,797 PC patients treated with either RT (n = 3,219) or RP (n =5,578). Patients subjected to RT were elder (higher percentage of 70≧years, p < 0.0001) and more advanced clinically (stage III: 22.90% vs. 11.87%; stage IV: 22.15% vs. 13.80%, p < 0.0001), compared to those subjected to RP. More patients subjected to RT had a much higher percentage of autoimmune disease (22.34% vs. 18.75%, p < 0.0001) and osteoarthritis and allied disorders (16.31% vs. 12.98%, p < 0.0001). Besides, RT patients had a higher percentage of underlying Crohn's disease (0.25% vs. 0.05%, p = 0.0230). Although almost all selected factors were not statistically significant, they presented the positive risk of SCRC for those under RP compared with those among RT. Besides, for PC patients in clinical stage I and II, patients with RP may have borderline significantly protective effects of SCRC compared with those under RT (stage I, HR: 0.14; 95% C.I.:0.01-1.39; p = 0.0929; stage II, HR: 1.92; 95% C.I.:0.93-3.95; p = 0.0775). Kaplan-Meier curves for a 3-year-period, which demonstrated no statistical difference in the risk of SCRC free between PC patients undergoing RT and RP (p = 0.9766).

Conclusion: Whether or not pelvic RT for PC is associated with an increased risk for SCRC on a population-based level remains a matter of considerable debate. From a clinical perspective, these PC survivors should be counseled accordingly and received continued cancer surveillance with regular colonoscopy follow-up.

Keywords: secondary colorectal cancer, prostate cancer, radiotherapy, radical prostatectomy, large population-based study