Association of prostate size with urinary morbidity following mixed conformal neutron and photon irradiation

Purpose: This study was designed to characterize the relationship between t he observed rate of postradiation genitourinary (GU) complications and the prostate gland size. Methods and Materials: Two hundred seventy-three patients received conforma l neutron and photon irradiation to the prostate seminal vesicles. Data on post-treatment urinary morbidity were collected and examined in relationshi p to a number of clinical and technical factors. Results: With a median follow-up of 30 months (range 7-61), the 4-year rate of Grade 2 or higher GU complications was 21%, on univariate analysis, the risk of complications was significantly associated with prostate size and neutron beam arrangement. On multivariate analysis, only the prostate size was significantly associated with the risk of GU morbidity. Patients with a preradiation prostate volume more than 74 cc had a two and a half fold inc rease in the risk of complications compared to patients with smaller glands . Conclusion: Patients with an enlarged prostate have a significantly higher risk of chronic GU complications. Although these data were obtained for pat ients receiving combined neutron and photon irradiation, it is likely that these data would also be applicable for those patients receiving photon irr adiation as well. These observations may add an additional rationale for th e study of preirradiation hormonal treatment. (C) 1999 Elsevier Science Inc .