Intensity-Modulated Radiation Therapy with Simultaneous Integrated Boost for Clinically Node-Positive Prostate Cancer: A Single-Institutional Retrospective Study

This study aimed to evaluate clinical outcomes and the toxicity of intensity-modulated radiation therapy with simultaneous integrated boost (SIB-IMRT) combined with androgen-deprivation therapy for clinically node-positive (cN1) prostate cancer. We retrospectively analyzed 97 patients with cN1 prostate cancer who received SIB-IMRT between June 2008 and October 2017 at our hospital. The prescribed dosages delivered to the prostate and seminal vesicle, elective node area, and residual lymph nodes were 69, 54, and 60 Gy in 30 fractions, respectively. Kaplan–Meier analysis was used to determine 5-year biochemical relapse-free survival (bRFS), relapse-free survival (RFS), overall survival (OS), and prostate cancer-specific survival (PCSS). Toxicity was evaluated using the Common Terminology Criteria for Adverse Events ver. 4.0. Over a median follow-up duration of 60 months, the 5-year bRFS, RFS, OS, and PCSS were 85.1%, 88.1%, 92.7% and 95.0%, respectively. Acute Grade 2 genito-urinary (GU) and gastro-intestinal (GI) toxicities were observed in 10.2% and 2.1%, respectively, with no grade ≥3 toxicities being detected. The cumulative incidence rates of 5-year Grade ≥2 late GU and GI toxicities were 4.7% and 7.4%, respectively, with no Grade 4 toxicities being detected. SIB-IMRT for cN1 prostate cancer demonstrated favorable 5-year outcomes with low incidences of toxicity.