# The Impact of Radiation Proctopathy on Secondary-Primary Colorectal Cancer in Patients with Prostate Cancer

## TL;DR

This study finds that prostate cancer patients who develop radiation proctopathy have a significantly higher risk of later developing colon and rectal cancer.

## Contribution

The study establishes radiation proctopathy as an independent risk factor for secondary colorectal cancer in prostate cancer patients.

## Key findings

- Patients with radiation proctopathy had 3.75% colorectal cancer incidence compared to 0.63% in those without.
- Radiation proctopathy was associated with a 4.43-fold higher risk of colon cancer and 7.27-fold higher risk of rectal cancer.
- The follow-up period showed statistically significant differences in cancer incidence between the groups.

## Abstract

We designed this study to evaluate the relationship between radiation proctopathy (RP) and the risk of colon and rectal cancer in prostate cancer patients.

This is a retrospective cohort study evaluating patients with prostate cancer who received pelvic radiation therapy between January 2004 and January 2024. The study aims to compare the incidence of post-radiation rectal and colon cancer between patients who developed RP and patients who did not. We excluded patients with a previous history of colon cancer, colectomy, or inflammatory bowel disease.

In total, 12,629 met the inclusion criteria, 533 patients were diagnosed with RP, and 12,096 were without. We observed a higher incidence of colorectal cancer (3.75% vs. 0.63%), colon cancer (2.06% vs 0.40%), and rectal cancer (1.69% vs 0.23%) in patients with RP compared to those without PR (p < 0.001) during the follow-up period of 81 months for the RP group and 68 months for the non-RP group. PR was associated with colon and rectal cancer with an HR of 4.43 (95% CI, 2.29–8.57; p < 0.0001) and 7.27 (95% CI, 3.43–15.43; p < 0.0001), respectively.

RP is an independent risk factor for developing rectal and colon cancer after pelvic radiation therapy in patients with prostate cancer.