Late gastrointestinal toxicities following radiation therapy for prostate cancer.

BACKGROUND: Radiation therapy is commonly used to treat localized prostate cancer; however, representative data regarding treatment-related toxicities compared with conservative management are sparse.
OBJECTIVE: To evaluate gastrointestinal (GI) toxicities in men treated with either primary radiation or conservative management for T1-T2 prostate cancer. DESIGN, SETTING, AND PARTICIPANTS: We performed a population-based cohort study, using Medicare claims data linked to the Surveillance Epidemiology and End Results data. Competing risk models were used to evaluate the risks. MEASUREMENTS: GI toxicities requiring interventional procedures occurring at least 6 mo after cancer diagnosis. RESULTS AND LIMITATIONS: Among 41,737 patients in this study, 28,088 patients received radiation therapy. The most common GI toxicity was GI bleeding or ulceration. GI toxicity rates were 9.3 per 1000 person-years after three-dimensional conformal radiotherapy, 8.9 per 1000 person-years after intensity-modulated radiotherapy, 5.3 per 1000 person-years after brachytherapy alone, 20.1 per 1000 person-years after proton therapy, and 2.1 per 1000 person-years for conservative management patients. Radiation therapy is the most significant factor associated with an increased risk of GI toxicities (hazard ratio [HR]: 4.74; 95% confidence interval [CI], 3.97-5.66). Even after 5 yr, the radiation group continued to experience significantly higher rates of new GI toxicities than the conservative management group (HR: 3.01; 95% CI, 2.06-4.39). Because our cohort of patients were between 66 and 85 yr of age, these results may not be applicable to younger patients.
CONCLUSIONS: Patients treated with radiation therapy are more likely to have procedural interventions for GI toxicities than patients with conservative management, and the elevated risk persists beyond 5 yr. Published by Elsevier B.V.