78 Background: Moderately hypofractionated radiotherapy has been increasingly adopted in the management of localized prostate cancer (PCa). We report 10-year outcomes for patients treated with intensity modulation radiation therapy (IMRT) for localized PCa with 70 Gy in 28 fractions at 2.5 Gy/fraction. Methods: This retrospective study included 854 consecutive patients with localized PCa treated with image-guided moderately hypofractionated IMRT at a single institution between 1998 and 2012. Patients with a single intermediate-risk factor were considered to have favorable intermediate-risk (FIR) disease; multiple intermediate-risk factors were considered unfavorable (UIR). Biochemical relapse free survival (bRFS), clinical relapse free survival (cRFS), overall survival (OS) and PCa specific mortality (PCSM) were analyzed used Kaplan-Meier analysis. Grade ≥3 genitourinary (GU) and gastrointestinal (GI) toxicities were recorded (CTCAE v4.03). Results: The median follow-up was 11.3 years (Max. 19 years). For patients with low-risk (LR, 31%), FIR (28%), UIR (12.5%), and high-risk (HR, 28.5%) disease the 10 year bRFS rates were 88%, 78%, 71% and 42%, respectively (p < 0.0001). The number of patients receiving no ADT, 1-6 months, or > 6 months of ADT were 39%, 50%, and 11%, respectively, reflecting practice patterns during this treatment period. The 10-year cRFS were 95%, 91%, 85% and 72% for patients with LR, FIR, UIR, and HR, respectively (p < 0.0001). The 10-year actuarial OS rate was 69% (95% CI 66-73%) and the 10-year PCSM was 6.8% (95% CI 5.1-8.6%) overall. For patients with LR, FIR, UIR and HR disease, the 10 year PCSM rates were 2%, 5%, 5% and 15%. 10-year cumulative incidence of grade ≥3 GU and GI toxicity was 2% and 1%, respectively. Multivariate analysis identified associations between clinical variables (ADT use, PSA nadir < 0.5ng/ml, and ISUP Grade Group) and bRFS, cRFS, and PCSM. Conclusions: Moderately hypofractionated IMRT with daily image guidance for localized PCa demonstrates favorable 10-year oncologic outcomes with a low incidence of toxicity for patients across all risk groups.
Year of treatment as an independent predictor of relapse-free survival in patients with localized prostate cancer treated with definitive radiotherapy in the PSA era
