Long-term outcomes from a multicentre study of HDR monotherapy with a single fraction of 19 Gy for localized prostate cancer

Objectives: To evaluate long-term clinical outcomes, toxicity, and prognostic factors in patients with localized prostate cancer treated with single-fraction high-dose-rate (HDR) brachytherapy. Methods: This multicentre retrospective study included patients from five UK centres who received a single 19 Gy HDR brachytherapy fraction under a standardized protocol. Kaplan-Meier estimates were calculated at median 5 and 8 years for biochemical progression-free survival (bPFS), local recurrence-free survival (LRFS), nodal recurrence-free survival (NRFS), distant metastasis-free survival (DMFS), and overall survival (OS). Prognostic factors were assessed using Cox regression. Toxicities were graded using CTCAEv3.0. Quality of life (QoL) was evaluated using IPSS, IIEF, and FACT-P questionnaires. Results: A total of 320 patients were included, with a median follow-up of 94 months. Five- and 8-year rates were: bPFS 77.1%/66.5%, LRFS 96.1%/90.9%, NRFS 98.3%/97.3%, DMFS 95.9%/93.8%, and OS 91.4%/87.0%. Low-risk patients had significantly better bPFS than intermediate and high-risk (HR12.55, 95%CI:1.74–90.05,p = 0.012), though no significant differences were seen in other outcomes. Subcentimetre pelvic lymph nodes on MR scan were associated with poorer bPFS, LRFS, DMFS, and OS. GS ≥ 8 predicted worse OS. Acute and late ≥ grade 2 GU toxicities occurred in 3.1% and 19.3% of patients, respectively; GI toxicities in 0.8% and 1.5%. QoL scores worsened post-treatment: IPSS + 7 points (p < 0.001), IIEF −9 points (p = 0.043), and FACT-P −3 points (p = 0.02) and returned to baseline. Conclusion: Single-fraction 19 Gy HDR brachytherapy was tolerable and provided disease control, though contemporary practice favors active surveillance for most low-risk patients. For higher-risk disease, a single fraction is not equivalent to standard multifraction regimens, indicating its role should remain limited.