Hypofractionated intensity-modulated arc therapy for lymph node metastasized prostate cancer: early late toxicity and 3-year clinical outcome.

Abstract

For patients with N1 prostate cancer (PCa) aggressive local therapies can be advocated. We evaluated clinical outcome, gastro-intestinal (GI) and genito-urinary (GU) toxicity after intensity modulated arc radiotherapy (IMAT)+androgen deprivation (AD) for N1 PCa. Eighty patients with T1-4N1M0 PCa were treated with IMAT and 2-3years of AD. A median dose of 69.3Gy (normalized isoeffective dose at 2Gy per fraction: 80Gy [α/β=3]) was prescribed in 25 fractions to the prostate. The pelvic lymph nodes received a minimal dose of 45Gy. A simultaneous integrated boost to 72Gy and 65Gy was delivered to the intraprostatic lesion and/or pathologically enlarged lymph nodes, respectively. GI and GU toxicity was scored using the RTOG/RILIT and RTOG-SOMA/LENT-CTC toxicity scoring system respectively. Three-year actuarial risk of grade 2 and 3/4 GI-GU toxicity and biochemical and clinical relapse free survival (bRFS and cRFS) were calculated with Kaplan-Meier statistics. Median follow-up was 36months. Three-year actuarial risk for late grade 3 and 2 GI toxicity is 8% and 20%, respectively. Three-year actuarial risk for late grade 3-4 and 2 GU toxicity was 6% and 34%, respectively. Actuarial 3-year bRFS and cRFS was 81% and 89%, respectively. Actuarial 3-year bRFS and cRFS was, respectively 26% and 32% lower for patients with cN1 disease when compared to patients with cN0 disease. IMAT for N1 PCa offers good clinical outcome with moderate toxicity. Patients with cN1 disease have poorer outcome.