Nonrandomized comparison of efficacy and side effects of bicalutamide compared with luteinizing hormone-releasing hormone (LHRH) analogs in combination with radiation therapy in the CHHiP trial

Abstract

Purpose: CHHiP is a randomized trial evaluating moderately hypofractionated radiation therapy for treatment of localized prostate cancer. Of all participants, 97% of them had concurrent short-course hormone therapy (HT), either luteinizing hormone-releasing hormone analog (LHRHa) or 150 mg of bicalutamide daily. This exploratory analysis compares efficacy and side effects in a nonrandomized comparison. Methods and materials: In our study, 2700 patients received LHRHa and 403 received bicalutamide. The primary endpoint was biochemical/clinical failure. Groups were compared with Cox regression adjusted for various prognostic factors and stratified by radiation therapy dose. A key secondary endpoint was erectile dysfunction (ED) assessed by clinicians (using scores from Late Effects on Normal Tissues: Subjective/Objective/Management [LENT-SOM] subjective erectile function for vaginal penetration) and patients (single items within the University of California-Los Angeles Prostate Cancer Index [UCLA PCI] and Expanded Prostate Cancer Index Composite [EPIC]-50 questionnaires) at 2 years and compared between HT regimens by χ2 trend test. Results: Bicalutamide patients were significantly younger (median 67 vs 69 years LHRHa). Median follow-up was 9.3 years. There was no difference in biochemical or clinical failure with an adjusted hazard ratio or 0.97 (95% confidence interval, 0.77-1.23; P = .8). At 2 years, grade ≥2 LENT-SOM ED was reported in significantly more LHRHa patients (313 out of 590; 53%) versus bicalutamide (17 out of 68; 25%) (P < .0001). There were no differences in ED seen with UCLA-PCI and EPIC-50 questionnaires. Conclusions: In this nonrandomized comparison, there was no evidence of a difference in efficacy according to type of HT received. Bicalutamide preserved clinician assessed (LENT-SOM) erectile function at 2 years but patient-reported outcomes were similar between groups.