KEY POINTS
- This international retrospective study included 75 patients across four centres treated for N0/M0 local recurrence within the previously irradiated prostate or prostate bed using daily adaptive 1.5-T MR-Linac re-irradiation.
- The median interval from previous radical treatment to recurrence was 79.0 months (IQR 56.2–126.5), median PSA at recurrence was 2.2 ng/mL, and median age at re-irradiation was 73.3 years.
- SBRT schedules varied, but 30 Gy in 5 fractions was the most common regimen. Treatment was focal/GTV-only in 46.7% and whole-gland in 53.3%.
- Early GU toxicity was modest: at three months, grade 2 events occurred in 13.3% and grade 3 in 1.3%. Grade 3 toxicity increased to 3.8% at six months and 12.5% at 12 months among evaluable patients, with urinary retention, haematuria, and frequency among the reported severe events.
- No grade 4–5 GU events occurred. Gastrointestinal toxicity was substantially lower, with no grade ≥2 GI adverse events at any reported timepoint.
- Failure-free survival was 96.6% at 12 months (95% CI 92.0–100.0%) and 76.5% at 24 months (95% CI 62.8–93.2%). Failures observed within two years remained confined to intraprostatic, prostate-bed, or seminal-vesicle sites.
- Interpretation is limited by heterogeneous target definition, fractionation and ADT use across centres, missing later toxicity data, lack of prospective patient-reported outcomes, and median follow-up of only 11.9 months.
CLINICAL TAKEAWAY
Daily adaptive MR-guided SBRT offers a credible nonsurgical salvage option for carefully selected locally recurrent prostate cancer, with excellent early disease control and minimal GI morbidity. The important counterweight is GU toxicity: grade 3 events accumulated over time, reaching 12.5% at one year, making longer prospective follow-up essential.