PD12-12 ADJUVANT RADIOTHERAPY IMPROVES CANCER-SPECIFIC SURVIVAL ONLY IN PATIENTS WITH HIGHLY AGGRESSIVE PROSTATE CANCER. VALIDATION OF RECENTLY RELEASED CRITERIA

Abstract

INTRODUCTION AND OBJECTIVES: Radical prostatectomy (RP) and initial observation may be considered as therapeutic options for the management of patients with locally advanced prostate cancer (PCa). The aim of our study was to describe the survival benefit associated with RP, as compared to initial observation, in these patients. Specifically, we relied on competing-risks analyses to estimate cancer-specific mortality (CSM) rates of patients treated with RP and to compare them to patients treated with initial observation. METHODS: Overall, 1,382 patients with locally advanced PCa (clinical stage T3/T4) treated with RP or initial observation between 1995 and 2009 within the Surveillance, Epidemiology, and End Results Medicare-linked were evaluated. Patients in both treatment arms (RP vs. observation) were matched using propensity-score methodology. Ten-year cancer-specific mortality (CSM) rates were estimated, and the number needed to treat (NNT) was calculated. Competing-risks regression analyses tested the relationship between treatment type and CSM. All analyses were repeated after stratifying patients according to Gleason score ( 7 vs. 8-10) and clinical stage (T3a vs. T3b/T4). RESULTS: Overall, 908 (65.7%) and 474 (34.3%) patients were treated with observation and RP. Overall, the 10-year CSM rates were 11.8 vs. 19.3% for patients treated with RP vs. initial observation, respectively (P<0.001). The corresponding 10-year NNT was 13. The 10-year CSM rates for the same respective treatment groups were 8.9 vs. 13.9% for Gleason score 7, 16.8 vs. 27.8% for Gleason score 8-10, 10.1 vs. 15.8% for clinical stage T3a, and 17.0 vs. 29.3% for clinical stage T3b/T4, respectively (all P 0.04). The corresponding NNTs were 20, 9, 17, and 8, respectively. In multivariable analyses, RP was an independent predictor of more favorable CSM in all categories (all P 0.04). CONCLUSIONS: Radical prostatectomy leads to a significant survival advantage compared to initial observation in patients with locally advanced disease. Particularly, 13 men with clinical stage T3/T4 should be treated with surgery to prevent one cancer-related death at 10-year follow-up. The highest survival benefit was observed in patients with more aggressive disease (i.e., clinical stage T3b/T4 and Gleason score 8-10 PCa). As such, surgery should be considered in these individuals when feasible.