Postoperative high-dose pelvic radiotherapy for N+ prostate cancer: toxicity and matched case comparison with postoperative prostate bed-only radiotherapy.

PURPOSE: To report on toxicity of postoperative high-dose whole-pelvis radiotherapy (WPRT) with androgen deprivation therapy for lymph node metastasized (N1) prostate cancer (PC). To perform a matched-case analysis to compare this toxicity profile to postoperative prostate bed-only radiotherapy (PBRT).
MATERIALS AND METHODS: Forty-eight N1-PC patients were referred for WPRT and 239 node-negative patients for PBRT. Patients were matched 1:1 according to pre-treatment demographics, symptoms, treatment and tumor characteristics. Mean dose to the prostate bed was 75Gy (WPRT-PBRT) and 54Gy to the elective nodes (WPRT) in 36 or 37 fractions. End points are genito-urinary (GU) and gastro-intestinal (GI) toxicity.
RESULTS: After WPRT, 35% developed grade 2 (G2) and 4% G3 acute GU toxicity. Acute GI toxicity developed in 42% (G2). Late GU toxicity developed in 36% (G2) and 7% (G3). One patient had G4 incontinence. Recuperation occurred in 59%. Late GI toxicity developed in 25% (G2) with 100% recuperation. Incidence of acute and late GI toxicity was higher following WPRT compared to PBRT (p⩽0.041). GU toxicity was similar. With WPRT mean dose to bladder and rectosigmoid were higher.
CONCLUSIONS: Postoperative high-dose WPRT comes at the cost of a temporary increase in G2. GI toxicity compared to PBRT because larger volumes of rectosigmoid are irradiated.