Survival Benefit of Radical Prostatectomy in Patients with Localized Prostate Cancer: Estimations of the Number Needed to Treat According to Tumor and Patient Characteristics

Purpose: The benefit of active treatment for prostate cancer is a subject of continuous debate. We assessed the relationship between treatment type (radical prostatectomy vs observation) and cancer specific mortality in a large, population based cohort. Materials and Methods: We examined the records of 44,694 patients treated with radical prostatectomy or observation between 1992 and 2005 in the SEER (Surveillance, Epidemiology and End Results)-Medicare linked database. Patients were matched by propensity score. Competing risks analysis was done to test the effect of treatment type on cancer specific mortality after accounting for other cause mortality. The number needed to treat was calculated. All analysis was stratified by prostate cancer risk group, baseline Charlson comorbidity index and patient age. Results: For patients treated with radical prostatectomy vs observation the 10-year cancer specific mortality rate was 5.2% vs 12.8% for high risk prostate cancer, 1.4% vs 3.8% for low-intermediate risk prostate cancer, 2.4% vs 5.8% for a Charlson comorbidity index of 0, 2.3% vs 6.4% for a comorbidity index of 1, 2.5% vs 5.4% for a comorbidity index of 2 or greater, 2.0% vs 4.6% at ages 65 to 69, 2.6% vs 5.6% at ages 70 to 74 and 2.7% vs 8.1% at ages 75 to 80 years (each p < 0.001). The corresponding number need to treat was 13, 42, 29, 24, 34, 38, 33 and 19, respectively. On multivariable analysis radical prostatectomy was an independent predictor of more favorable cancer specific mortality in all categories (each p < 0.001). Conclusions: Patients with high risk prostate cancer benefit the most from radical prostatectomy. The lowest benefit was observed in patients with low-intermediate risk prostate cancer. An intermediate benefit was observed when patients were classified by Charlson comorbidity index and age category.