Acute Toxicity Profiles of Hypofractionated Adjuvant and Salvage Radiation Therapy After Radical Prostatectomy: Results of a Prospective Study

Purpose: Hypofractionated radiation therapy (RT) is controversial after radical prostatectomy (RP). In this interim analysis, our prospective observational study assessed acute genitourinary (GU) and gastrointestinal (GI) toxicity after hypofractionated adjuvant and salvage RT, as delivered by helical tomotherapy (HT), in patients with prostate cancer. Methods and Materials: After undergoing RP with or without pelvic lymph node dissection, 112 patients were enrolled. Hypofractionated adjuvant RT (2.25 Gy daily for 29 fractions; total 65.25 Gy) was administered to 40 patients with high-risk features. Hypofractionated salvage RT (2.25 Gy daily for 32 or 33 fractions; total 72-74.25 Gy) was prescribed for 72 patients (24 with biochemical relapse, 48 with local relapse). Toxicity was graded according to the Common Terminology Criteria for Adverse Events version 4.02. The impact of RT on urinary flow was assessed by uroflowmetry. Results: Acute GU toxicity occurred in 41 of 112 patients (36%) (G1 31, G2 10). Acute GI toxicity was observed in 55 (49%) patients (G1 44, G2 11). Uroflowmetry showed that only salvage RT reduced maximum flow significantly (maximum, 68 vs 50 mL/s; P =.003), perhaps because a higher RT dose had been administered. Conclusions: After RP, moderate hypofractionated adjuvant and salvage RT were associated with acceptable incidences of slight-to-moderate acute GU and GI toxicity and had little impact on urinary flow. Prospective trials are warranted with longer follow-up in larger cohorts to confirm these findings.