Reirradiation for isolated local recurrence of prostate cancer: Mono-institutional series of 64 patients treated with salvage stereotactic body radiotherapy (SBRT)

Objective: To evaluate high-precision external beam reirradiation (re-EBRT) for local relapse of prostate cancer (PCa) after radiotherapy. Methods: This retrospective study included patients with biochemical failure and evidence of isolated local recurrence of PCa after radical/salvage EBRT or brachytherapy that received salvage stereotactic body radiation therapy (SBRT, re-EBRT). Biopsy was not mandatory if all diagnostic elements were univocal (prostate specific antigen evolution, choline-positron emission tomography or magnetic resonance imaging). Salvage SBRT (re-EBRT) was delivered with image-guided radiation therapy (RapidArc (R), VERO (R) and CyberKnife (R)). Results: Data of 64 patients were included, median age at salvage SBRT was 73.2 years, median pre-salvage SBRT prostate specific antigen was 3.89 ng m1 -1 . Median total dose was 30 Gy in five fractions, biologically effective dose (BED) of 150 Gy. One acute G3 genitourinary event and one late G3 genitourinary event were observed. No G > 3 bowel toxicity was registered. At the median follow-up of 26.1 months, tumor progression was observed in 41 patients (64%). 18 patients (28%) experienced local relapse. 2-year local control, biochemical and clinical relapse free survival rates were 75, 40 and 53%, respectively. With BED >130 Gy 1-year biochemical and clinical progression-free survival rate were 85 and 90%, respectively. Conclusions: Salvage SBRT (re-EBRT) for isolated local PCa recurrence is a safe, feasible and noninvasive salvage treatment. Further investigation is warranted to define the optimal patient selection, dose and volume parameters. Advances In knowledge: Salvage SBRT reirradiation for the locally recurrent PCa offer a satisfactory tumor control and excellent toxicity profile, if BED >= 130 Gy is administered.