Is Bicalutamide Equivalent to Goserelin for Prostate Volume Reduction before Radiation Therapy? A Prospective, Observational Study

Abstract

Introduction: We compare the cytoreductive efficacy of bicalutamide or goserelin with no hormonal manipulation in prostate cancer before brachytherapy. Materials and methods: Transrectal ultrasound volume estimations were performed in clinic and during the brachytherapy-planning scan. Between volume estimations, patients received no hormonal treatment, bicalutamide 150mg once daily or goserelin 3.6mg every 28 days. Results: Patients receiving no hormonal manipulation had a volume increase of 8% compared with an 8% volume reduction in the bicalutamide group and a 26% reduction in the goserelin group. As initial prostate volume was not equivalent in the three groups, a subgroup analysis was performed on patients who received active treatment for more than 3 months who had initial prostate volume less than 55cm³. In this subgroup, a mean fall in prostate volume of 7% occurred in the bicalutamide group compared with 21% in the goserelin group. In both the original and subgroup analysis, the cytoreductive efficacy of goserelin was significantly greater than bicalutamide (P<0.0001). Conclusion: In the absence of data from randomised trials, comparing the efficacy of these agents, luteinising hormone-releasing hormone (LHRH) analogues remain the gold standard for cytoreduction before prostate brachytherapy. If the neoadjuvant efficacy of hormonal manipulation in external beam radiotherapy is dependent on prostate volume reduction, then LHRH analogues may also prove more effective in this neoadjuvant role.