Ten-year outcomes of moderately hypofractionated (70 Gy in 28 fractions) intensity modulated radiotherapy for localized prostate cancer
Menée à partir de données portant sur 854 patients atteints d'un cancer localisé de la prostate (durée médiane de suivi : 11,3 ans), cette étude évalue la toxicité et les taux de survie à 10 ans d'une radiothérapie avec modulation d'intensité et hypofractionnement modéré
Purpose/objectives : Long term outcomes with hypofractionated radiotherapy for prostate cancer are limited. We report 10-year outcomes for patients treated with intensity modulated radiation therapy (IMRT) for localized prostate cancer with 70 Gy in 28 fractions at 2.5 Gy/fraction. Methods and Materials : The study included 854 consecutive patients with localized prostate cancer treated with moderately hypofractionated IMRT and daily image guidance at a single institution between 1998 and 2012. Patients with a single intermediate-risk factor were considered to have favorable intermediate-risk (FIR) disease, and those with multiple intermediate-risk factors were considered unfavorable (UIR). Biochemical relapse free survival (bRFS), clinical relapse free survival (cRFS), overall survival (OS) were analyzed using Kaplan-Meier analysis. Prostate Cancer Specific Mortality (PCSM) was analyzed using competing risk regression. All grade ≥3 genitourinary (GU) and gastrointestinal (GI) toxicities were recorded using CTCAE version 4.03 and cumulative incidence rates of GU and GI toxicity were calculated. Results : The median follow-up was 11.3 years (maximum, 19 years). For patients with low-risk (LR), FIR, UIR, and high-risk (HR) disease the 10-year bRFS rates were 88%, 78%, 71% and 42%, respectively (p <0.0001). The 10-year cRFS were 95%, 91%, 85% and 72% for patients with LR, FIR, UIR, and HR, respectively (p <0.0001). For all patients, the 10-year actuarial OS rate was 69% (95% confidence interval (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%. Long term grade ≥3 GU or GI toxicity remained low with 10-year cumulative incidences of 2% and 1%, respectively. Conclusion : High-dose moderately hypofractionated IMRT with daily image guidance for localized prostate cancer demonstrates favorable 10-year oncologic outcomes with a low incidence of toxicity. This fractionation schedule appears to be acceptable for patients across all risk groups.