BACKGROUND AND OBJECTIVE The optimal management of prostate cancer (PC) recurrences after definitive or postoperative radiotherapy (RT) is still controversial. The aim of the present retrospective study was to report the preliminary clinical results and toxicity of a mono-institutional series of patients re-irradiated with linac-based SBRT in recurrent prostate cancer. METHODS Inclusion criteria were previous definitive or adjuvant/salvage RT, evidence of biochemical recurrence and radiological detection of local relapse (Magnetic Resonance Imaging or PSMA/choline-Positron Emission Tomography), and IPSS <10. Toxicity was assessed according to Common Terminology Criteria for Adverse Events v4.0. RESULTS Between 12/2014 and 12/2019, 24 patients with median age 75 years (65-89) underwent re-RT for PC recurrence. Median follow-up was 21 months (2-68). The recurrences occurred in 13 cases within the prostate and in 11 cases within the prostate bed. All patients were treated with SBRT to a median total dose of 30 Gy (25-36 Gy) in 5-6 fractions, and simultaneous androgen deprivation therapy was administered in 4 patients. Acute toxicity was G1 in 8.3% and G2 in 12.5% for genitourinary (GU), no acute gastrointestinal (GI) toxicity occurred. Concerning late side effects, 19.7% of patients were found to have ≥G2 GU toxicity, including one G3 urethral stenosis. Only one case of G1 late GI toxicity occurred and no ≥G2. The 2‑year overall survival was 95%. The 1‑ and 2‑year biochemical relapse-free survival (BRFS) and progression-free survival (PFS) rates were 80 and 54.9%, respectively. CONCLUSION Despite of the heterogeneity of the sample, linac-based SBRT as a salvage treatment in previously irradiated locally recurrent PC patients seems to be a safe and feasible treatment option. Long-term data are pending.

中文翻译：

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基于直线加速器的SBRT可作为先前接受放射治疗的前列腺癌局部复发的可行挽救选择。

背景和目的确定性或术后放疗（RT）后前列腺癌（PC）复发的最佳治疗仍存在争议。本回顾性研究的目的是报告以直线加速器为基础的SBRT再照射的单机构系列患者在复发性前列腺癌中的初步临床结果和毒性。方法纳入标准为先前的确定性或辅助性/挽救性RT，生化复发证据和局部复发的放射学检测（磁共振成像或PSMA /胆碱-正电子发射断层扫描），并且IPSS <10。毒性根据不良事件通用术语标准v4.0进行评估。结果在12/2014至12/2019之间，中位年龄为75岁（65-89）的24例患者接受了PC复发的再次放疗。中位随访时间为21个月（2-68）。复发发生在前列腺内的13例和前列腺床内的11例中。所有患者均接受SBRT治疗，中位总剂量为5-6个部分，总剂量为30 Gy（25-36 Gy），其中4例患者同时进行了雄激素剥夺治疗。泌尿生殖系统（GU）的急性毒性为8.3％的G1和12.5％的G2，没有发生急性胃肠道（GI）毒性。关于后期副作用，发现19.7％的患者具有≥G2 GU毒性，包括一种G3尿道狭窄。仅发生1例G1晚期胃肠道毒性，且不≥G2。2年总生存率为95％。1年和2年生化无复发生存率（BRFS）和无进展生存率（PFS）分别为80％和54.9％。结论尽管样本具有异质性，基于直线加速器的SBRT作为先前接受过放射治疗的局部复发PC患者的抢救治疗似乎是一种安全可行的治疗选择。长期数据正在处理中。