Reirradiation of Locally Recurrent Prostate Cancer With Volumetric Modulated Arc Therapy

Abstract

This study explores the efficacy and safety of reirradiation with modern radiation therapy techniques in patients previously irradiated for prostate cancer and affected by local relapse of disease. Patients affected by previously irradiated prostate cancer were enrolled in this reirradiation study if they had a biochemical relapse and a 11C-choline positron emission tomography scan revealing the presence of a local recurrence of disease. Reirradiation consisted of a stereotactic treatment delivered by image guided radiation therapy-volumetric modulated arc therapy with flattening filter-free technology in 5 daily fractions. Twenty-three patients underwent reirradiation to the prostate, prostatic bed, or prostate and local recurrence. Re-treatment consisted of a median total dose of 25Gy in 5 fractions. A biochemical response was observed in all cases. Acute toxicity was mainly genitourinary (GU) grade 1 to 2 (n=13; 56.5%). One patient (4.3%) had grade 3 hematuria. A grade 1 GU late toxicity was registered in 4 patients (17.4%) and grade 3 in 1 patient (4.3%, urethral obstruction). Gastrointestinal toxicity was negligible. Regression analysis showed that only a short elapsed time in months from primary radiation therapy was significantly correlated with acute GU toxicity. After a median follow-up of 33months (range, 5-58months), the median biochemical recurrence-free survival was 19months, and the 2-year biochemical recurrence-free survival (BRFS) was 41.7%. Median local control was 30months; the 2-year local control rate was 58.1%. Reirradiation of patients with prostate cancer who underwent previous radiation therapy is a valuable option that can be safely considered to delay the beginning of hormonal treatment.