Purpose: We describe the results of North American Trial 23 of the bicalutamide (Casodex) early prostate cancer program in the context of the overall early prostate cancer program findings.
Materials and methods: In Trial 23, 3,292 men with T1b-4, N0-Nx (N+ not allowed) M0 prostate cancer who had undergone radical prostatectomy or radiotherapy at 96 specialist referral centers in the United States (2,974) and Canada (318) were randomized 1:1 to 150 mg bicalutamide daily or placebo in addition to standard care for 2 years.
Results: In Trial 23 at a 7.7-year median followup there were few clinical events in the bicalutamide or standard care groups and the rates of objective progression were 15.4% and 15.3%, respectively. Mortality rates were 12.9% in the treatment group and 12.3% in the standard care group, including 11.2% and 11.0% for nonprostate cancer deaths in the absence of objective progression and 1.6% and 0.9%, respectively, for mortality due to prostate cancer. No differences in the primary end points (objective progression-free and overall survival) were seen between patients treated with bicalutamide and those treated with standard care alone. Bicalutamide (150 mg) significantly improved time to PSA progression (HR 0.80, 95% CI 0.72 to 0.90, p <0.001). The tolerability profile of bicalutamide was similar to that previously described.
Conclusions: In Trial 23 the current data suggest that early or adjuvant therapy may not benefit patients at low risk for recurrence, such as those with localized disease. The findings of Trial 23 contrast with the results in the overall early prostate cancer program and in other published literature, in which bicalutamide has been shown to provide significant clinical benefit for locally advanced disease.