Purpose: Inflammatory bowel disease (IBD) is a relative contraindication for radiotherapy due to perceived increased risk of bowel toxicity. We aimed to evaluate the safety of stereotactic body radiotherapy (SBRT) for prostate cancer in men with IBD.

Methods/Materials: Queried a consortium database for patients with IBD receiving SBRT for prostate cancer between 2006-2012. Identified patients were matched with patients without IBD in a 3:1 fashion based on dose, fractionation, use of androgen deprivation therapy, and age distribution. Logistic regression was used to evaluate the association between having IBD and experiencing acute and late gastrointestinal (GI) and genitourinary (GU) toxicities as scored on the Common Terminology Criteria for Adverse Events scale. Time to late toxicity was evaluated using proportional hazard Cox models.

Results: Identified 39 patients with inactive IBD at time of treatment (median follow-up 83.9 months) and 117 matched controls (median follow-up 88.7 months). IBD was associated with increased odds of developing any late grade GI toxicity (odds ratio [OR] 6.11, P<0.001) and GU toxicity (OR 6.14, P<0.001), but not odds of developing late grade ≥2 GI (P=0.08) or GU toxicity (P=0.069). Acute GI and GU toxicity, both overall and for grade ≥2 toxicities, were more frequent in men with IBD (P<0.05). Time to late GI and GU toxicity of any grade was significantly shorter in patients with IBD (P<0.001). Time to late grade ≥2 GU, but not grade ≥2 GI toxicity, was also shorter in patients with IBD (P=0.044 for GU and P=0.144 for GI).

Conclusions: Odds of late grade ≥2 GI or GU toxicity following SBRT are not increased in men with IBD, though rates of acute toxicities and lower grade late toxicities are significantly higher, and late toxicities occur earlier. Men with inactive IBD should be properly counseled about these risks, but they remain candidates for SBRT.