Hypofractionated intensity-modulated radiation therapy for prostate cancer confined to the pelvis: analysis of efficacy and late toxicity

Abstract

We sought to evaluate the efficacy and safety of a hypofractionated intensity-modulated radiotherapy (IMRT) regimen for pelvic-confined prostate cancer in prostate-specific antigen (PSA)-unscreened Chinese patients. We prospectively enrolled 140 prostate cancer patients (T1–4N0–1M0) on a phase II protocol who were then treated with hypofractionated IMRT (2.7 Gy × 25 fractions; total 67.5 Gy). High-risk patients (≥30 % probability of pelvic nodal involvement, 55 patients) and patients with pelvic nodal enlargement (25 patients) also received 50 Gy in 25 fractions to the pelvic lymph nodes. Outcomes and toxicity data were analyzed for all patients at a median follow-up of 35 months. The 3-year overall survival and biochemical recurrence–free survival (bRFS) rates were 94.6 and 89.1 %, respectively. The bRFS at 3 years was 100 % for low/intermediate-risk patients, 89.6 % for high-risk patients, 82.5 % for very high risk patients, and 73.5 % for those with N1 disease. Cumulative grade ≥2 Radiation Therapy Oncology Group late gastrointestinal (GI) and genitourinary (GU) toxicity at 3 years was 26.4 and 18.6 %, respectively. There were four grade 3 GI and seven grade 3 GU events and one grade 4 GI and one grade 4 GU event. At the last follow-up, 8.5 and 9.3 % of patients had late grade ≥2 GI and GU toxicity, respectively, and 1.4 and 2.9 % patients had late grade ≥3 GI and GU toxicity, respectively. Moderately hypofractionated IMRT for prostate cancer is efficacious and well-tolerated in this predominantly high-risk, locally advanced, or N1 Chinese patients and is associated with low rates of severe late toxicity during early follow-up.