Outcomes and toxicities of re-irradiation for prostate cancer: A systematic review on behalf of the Re-Irradiation Working Group of the Italian Association of Radiotherapy and Clinical Oncology (AIRO)

Aims: The best therapeutic approach for local relapses of previously irradiated prostate cancer (PC) is still not defined. Re-irradiation (Re-I) could offer a chance of cure for highly selected patients, although high quality evidences are lacking. The aim of our study is to provide a literature review on efficacy and safety of Re-I. Methods: Only studies where Re-I field overlaps with previous radiotherapy were considered. To determine 2 and 4 years overall mortality (OM), 2 and 4 years biochemical failure (BF) and pooled acute and late G ≥ 3 toxicities rate, a meta-analysis over single arm study was performed. Results: Thirty-eight studies with 1194 patients were included. Median follow-up from Re-I was 30 months (10–94 months). Brachytherapy (BRT) was the most used Re-I technique (27 studies), followed by Stereotactic Body Radiotherapy (SBRT) (9) and External Beam Radiation Therapy (EBRT) (2). Re-I prescription doses ranged from 19 Gy in single HDR fraction to 145 Gy (interstitial BRT). The pooled 2 and 4 years OM rates were 2.1% (95%CI:1.1–3.7%, P < 0.001) and 12.5% (95%CI:8.1–19.5%; P < 0.001). The pooled 2 years BF rate was 24% (95% CI: 19.1–30.2%, P < 0.001). The pooled 4 years BF was 35.6% (95% CI: 28.7–44.3%, P < 0.001). The pooled result of G ≥ 3 acute toxicity was 1.4% (95%CI: 0.7–3%, P < 0.001). One hundred and three G ≥ 3 late adverse events were reported, with a pooled result of G ≥ 3 late toxicity of 8.7% (95%CI: 5.8–13%, P < 0.001). Conclusions: Re-I of local failures from PC showed promising OM and biochemical control rates with a safe toxicity profile.