Randomized non-inferiority trial of Bicalutamide and Dutasteride versus LHRH agonists for prostate volume reduction prior to I-125 permanent implant brachytherapy for prostate cancer.

To determine the efficacy and toxicity of a 3-month regimen of Dutasteride and Bicalutamide compared to LHRH agonists for prostate volume (PV) reduction prior to permanent implant prostate brachytherapy (PIPB).

Patients with low-risk or low-tier intermediate risk prostate cancer eligible for PIPB with a prostate volume greater than 50cc were randomized to either Dutasteride 0. 5mg Bicalutamide 50mg daily and Tamoxifen 10mg daily for 3months (D+B group) or to a 3month dose of an LHRH agonist and Bicalutamide daily for 1month (LHRH group). Their PV was measured at baseline and at pre-implant. Non-inferiority analysis was completed for the relative (%) PV reduction. IPSS and EPIC questionnaires were completed at baseline, pre-implant and at 1, 3, 6, 12, 18 and 24months post-treatment. IPSS and EPIC comparisons were based on superiority analysis RESULTS: 60 patients were randomized (31 to LHRH group and 29 to D+B group). Mean relative PV reduction (SD) was 35. 5% (8. 9) in the LHRH group and 31. 7% (9. 6) in the D+B group. The upper bound of the 95% confidence for the interval for the difference between groups favouring LHRH agonists for PV reduction was 8. 6 which did not cross the 10% non-inferiority margin meaning D+B is non-inferior to LHRH agonist for PV reduction, although 5/29 (17%) of those in the D+B group required longer duration of D+B to achieve adequate volume reduction. There were no statistically significant differences in IPSS scores over the entire follow-up period. EPIC sexual summary score was significantly better in the D+B group at pre-implant, 1month, 3months post-implant.

Dutasteride and Bicalutamide is a regimen of non-inferior efficacy to LHRH agonist based regimens for prostate volume reduction prior to permanent implant prostate brachytherapy. D+B has less sexual toxicity compared to LHRH agonists prior to implant and for the first 6months after implant. D+B is therefore an option to be considered for prostate volume reduction prior to PIPB.

Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. 2015 Dec 15 [Epub ahead of print]

Marc Gaudet, Éric Vigneault, William Foster, François Meyer, André-Guy Martin

Radiation Oncology, Centre Hospitalier Universitaire de Québec, Hôtel-Dieu de Québec, Canada; Radiation Oncology, Centre Intégré de Santé et Services Sociaux de l'Outaouais, Gatineau, Canada.  Radiation Oncology, Centre Hospitalier Universitaire de Québec, Hôtel-Dieu de Québec, Canada; Centre de recherche sur le cancer de l'Université Laval, Québec, Canada. , Radiation Oncology, Centre Hospitalier Universitaire de Québec, Hôtel-Dieu de Québec, Canada. , Centre de recherche sur le cancer de l'Université Laval, Québec, Canada. , Radiation Oncology, Centre Hospitalier Universitaire de Québec, Hôtel-Dieu de Québec, Canada; Centre de recherche sur le cancer de l'Université Laval, Québec, Canada.

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