Salvage Stereotactic Body Radiation Therapy for Local Prostate Cancer Recurrence After Radiation Therapy: A Retrospective Multicenter Study of the GETUG

Purpose: To assess the efficacy and safety of salvage stereotactic body radiation therapy (SBRT) in patients with biopsy-proven local prostate cancer recurrence after radiation therapy. Methods and Materials: Between April 2010 and January 2017, 100 patients were included in 7 centers. Disease extension was assessed by pelvic multiparametric magnetic resonance imaging and choline positron emission tomography in 87% and 94% of patients, respectively. The median time interval between the 2 treatments was 7.5 years (range, 2-18). Median prostate-specific antigen at recurrence was 4.3 ng/mL (range, 2-38). Median SBRT dose was 36 Gy (range, 25-36.25) in 6 fractions (range, 5-6), every other day. Thirty-four percent of patients were treated by androgen deprivation therapy for a median duration of 12 months. Toxicity was assessed according to Common Terminology Criteria for Adverse Events version 4.03. Results: Median follow-up was 29.3 months (range, 4-91). Second biochemical recurrence-free survival rate at 3 years was 55% (95% confidence interval [CI], 42%-66%). The initial D'Amico group, time interval after first radiation therapy, and SBRT dose were prognostic factors of biochemical recurrence-free survival in multivariate analysis (P = .09, P = .025, P = .018, respectively). No patient developed acute gastrointestinal toxicity of grade >1; rates of acute genitourinary toxicity of grade 2 and 3 were 8% and 1%, respectively. The actuarial 3-year grade >= 2 genitourinary and gastrointestinal toxicity was 20.8% (95% CI, 13%-29%) and 1% (95% CI, 0.1%-5.1%), respectively. One patient presented with neuritis of grade 3. Conclusions: With a short follow-up, this study shows that salvage SBRT allows for encouraging control and acceptable toxicity. Further prospective studies are necessary to confirm these preliminary results and to determine late toxicity. (C) 2019 Elsevier Inc. All rights reserved.