To analyze the impact of hormonal therapy (HT) on late gastrointestinal (GI) and genitourinary (GU) toxicity from external beam radiotherapy (RT).

The records of 445 consecutive patients with prostate cancer undergoing RT with or without HT were reviewed. Late toxicity rates, using established toxicity scoring guidelines, were tabulated in the two groups and compared using the chi-square test. Ordered logit regression analyses were performed that included the major demographic, disease, and treatment factors.

The chi-square analyses demonstrated lower rates of GI toxicity (P = 0.013) and GU toxicity (P = 0.041) in the cohort receiving HT; this reduction in toxicity appeared to be consistent across different toxicity grades. However, on regression analysis, the only factor reaching statistical significance in predicting late GI and late GU toxicity was the radiation dose (P = 0.004 and P = 0.047, respectively). In particular, on regression analysis, HT did not reach statistical significance in predicting late GI toxicity (P = 0.229) or late GU toxicity (P = 0.910).

Observed late RT toxicity rates were generally similar in patients who did and did not receive HT. Thus, increased late RT toxicity should not be a major concern when deciding to add HT to RT for treatment of localized prostate cancer.