RADIOTHERAPY DOSES OF 80 GY AND HIGHER ARE ASSOCIATED WITH LOWER MORTALITY IN MEN WITH GLEASON SCORE 8 TO 10 PROSTATE CANCER

Purpose: Men with Gleason score (GS) 8-10 prostate cancer (PCa) are assumed to have a high risk of micrometastatic disease at presentation. However, local failure is also a major problem. We sought to establish the importance of more aggressive local radiotherapy (RT) to >= 80 Gy. Methods and Materials: There were 226 men treated consecutively with RT +/- ADT from 1988 to 2002 for GS 8-10 PCa. Conventional, three-dimensional conformal or intensity-modulated (IM) RT was used. Radiation dose was divided into three groups: (1) <75 Gy (n = 50); (2) 75-79.9 Gy (n = 60); or (3) >= 80 Gy (n = 116). The endpoints examined included biochemical failure (BF; nadir + 2 definition), distant metastasis (DM), cause-specific mortality, and overall mortality (OM). Results: Median follow-up was 66, 71, and 58 months for Groups 1, 2, and 3. On Fine and Gray's competing risk regression analysis, significant predictors of reduced BF were RT dose >= 80 Gy (p = 0.011) and androgen deprivation therapy duration >= 24 months (p = 0.033). In a similar model of DM, only RT dose >= 80 Gy was significant (p = 0.007). On Cox regression analysis, significant predictors of reduced OM were RT dose >= 80 Gy (p = 0.035) and T category (T3/4 vs. T1, p = 0.041). Dose was not a significant determinant of cause-specific mortality. Results for RT dose were similar in a model with RT dose and ADT duration as continuous variables. Conclusion: The results indicate that RT dose escalation to >= 80 Gy is associated with lower risks of BF, DM, and OM in men with GS 8-10 PCa, independently of androgen deprivation therapy. (c) 2012 Elsevier Inc.