Effect of pretreatment prostate volume on urinary quality of life following intensity-modulated radiation therapy for localized prostate cancer

BACKGROUND: The aim of this study was to describe the effect of pretreatment prostate volume on urinary quality of life after intensity-modulated radiation therapy (IMRT) for clinically localized prostate cancer. METHODS: A total of 368 men treated with prostate IMRT (77.4–81 Gy) were stratified into three gland volume groups, ie, <30 g (group 1), 30–60 g (group 2), and >60 g (group 3). Post-IMRT urinary function was evaluated by National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) version 4.0 genitourinary guidelines at one year post-IMRT, and surveyed by the International Prostate Symptom Score (IPSS) before treatment, and then at one month and one year post-IMRT. RESULTS: Late (one year post-IMRT) CTCAE version 4.0 genitourinary toxicity occurred in 11/368 (3.0%) men, but was not severe (grade ≥ 3); total toxicity was similar between the prostate volume groups (P = 0.86). Continuous prostate volume neither correlated with (P = 0.50) nor predicted late genitourinary toxicity (univariate odds ratio 0.99, 95% confidence interval 0.96–1.02). The total IPSS cohort, group 1 (<30 g) and 2 (30–60 g), showed a similar IPSS trend of elevation from pretreatment baseline to one month post-IMRT (each P < 0.01), then a reduction to baseline at one year (each P < 0.01). Group 3 (>60 g) had the highest pretreatment IPSS, but uniquely showed a better urinary symptom trend than the smaller volume groups, with similar IPSS from baseline to one month post-IMRT (P = 0.88) and improved post-treatment IPSS from baseline at one year (P = 0.003). CONCLUSION: Pretreatment prostate volume and initial IPSS scores were not associated with increased late genitourinary toxicity after IMRT in our series. Patients with smaller prostates had an initial increase in urinary symptoms, but returned to baseline at one year. Larger prostate glands (>60 g) had comparatively worse pretreatment symptoms, but at one year showed an overall improvement in IPSS versus baseline.