The AVOCAT study: Bicalutamide monotherapy versus combined bicalutamide plus dutasteride therapy for patients with locally advanced or metastatic carcinoma of the prostate—a long-term follow-up…

Siebren Dijkstra, Wim P. J. Witjes, Erik P. M. Roos, Peter L. M. Vijverberg, Arno D. H. Geboers, Jos L. Bruins, Geert A. H. J. Smits, Henk Vergunst, Peter F. A. Mulders

Compare the efficacy and tolerability of dutasteride in combination with bicalutamide to bicalutamide monotherapy in the treatment of locally advanced and metastatic prostate cancer (PCa). One-hundred-fifty PCa patients with locally advanced or metastatic disease were prospectively enrolled and randomly assigned to receive either bicalutamide monotherapy 150 mg once daily (79 patients) or bicalutamide 150 mg plus dutasteride 0.5 mg once daily (71 patients). Treatment response was assessed by serum PSA level measurement, and standard procedures for diagnosis of clinical progression were used during follow-up. Patient-reported quality of life (QoL) was assessed using validated questionnaires (EORTC QLQ-C30 and QLQ-PR25). At 3 years follow-up, PSA progression was found in 52 patients [65.8 %; 95 % confidence interval (CI) 55.4-76.3] in the monotherapy group compared to 38 patients (53.5 %; 95 % CI 41.9-65.1) in the combined therapy group (p = 0.134). At the time of analysis 37 men (46.8 %; 95 % CI 35.8-57.8) in the monotherapy group had died versus 30 men (42.3 %; 95 % CI 30.8-53.7) in the combined therapy group. Median survival time was 5.4 and 5.8 years, respectively (p = 0.694). There was no statistically significant difference in the presentation frequency of adverse events between groups (p = 0.683). QoL was good and comparable between the two groups. Both therapies were well tolerated with a good QoL. However, despite a trend toward higher efficacy of the combined therapy, progression-free survival and overall survival was not significantly different between the groups. Further research on this therapy should be performed.