Purpose: To determine whether the number of unfavorable risk factors could be used to predict the risk of prostate cancer-specific mortality (PCSM) among men with intermediate- to high-risk prostate cancer.
Methods and materials: We studied 1,063 men who underwent radical prostatectomy (n = 559), external beam radiotherapy (n = 288), or radiotherapy plus androgen suppression therapy (n = 116) for prostate cancer between 1965 and 2002. Fine and Gray's regression analysis was used to determine whether an increasing number of unfavorable risk factors (prostate-specific antigen level >10 ng/mL, Gleason score of >or=7, clinical Stage T2b or greater, or pretreatment prostate-specific antigen velocity >2.0 ng/mL/y) was associated with the interval to PCSM and all-cause mortality.
Results: Median follow-up was 5.6 years. Compared with those with one risk factor, the adjusted hazard ratio for PCSM was 2.3 (95% confidence interval 1.1-4.8; p = 0.03) for two risk factors, 5.4 (95% confidence interval 2.7-10.7; p < 0.0001) for three risk factors, and 13.6 (95% confidence interval 6.3-29.2; p < 0.0001) for all four risk factors. The 5-year cumulative incidence of PCSM was 2.4% for one factor, 2.4% for two factors, 7.0% for three factors, and 14.7% for all four factors. Prostate cancer deaths as a proportion of all deaths was 19% for one factor, 33% for two factors, 53% for three factors, and 80% for four factors.
Conclusion: The number of unfavorable risk factors was significantly associated with PCSM. Prostate cancer was the major cause of death in men with at least three risk factors. Therefore, these men should be considered for clinical trials designed to assess whether survival is prolonged with the addition of novel agents to current standards of practice.