FocaSaBra: a prospective phase II study on focal salvage brachytherapy for prostate cancer recurrence after radiotherapy - trial design.

BACKGROUND

Recurrence of prostate cancer (PC) after primary radiotherapy poses a significant therapeutic challenge. While whole-gland salvage treatments carry considerable toxicity risks, focal salvage brachytherapy (FsBT) may preserve quality of life while achieving local control. The FocaSaBra trial is a prospective phase II study designed to evaluate the safety, feasibility, and oncologic efficacy of FsBT.

MATERIALS AND

METHODS

100 patients with intraprostatic recurrence confirmed by biopsy will be enrolled to the monocentric prospective trial. Depending on the primary radiation modality, patients will receive either high-dose-rate (HDR) FsBT with 26 Gy in 2 fractions using iridium-192 or ultra-low-dose-rate (uLDR) FsBT with iodine-125 seeds delivering 145 Gy. The dominant intraprostatic lesion (DIL) will be targeted with a 5-10 mm margin. The primary endpoint is the incidence of grade ≥ 3 genitourinary (GU) or gastrointestinal (GI) toxicity, assessed using CTCAE v4.0, RTOG scale, IPSS, IIEF, and EORTC QLQ-C30/PR25. Secondary endpoints include biochemical control and progression-free survival.

RESULTS

Toxicity and oncological outcomes will be analyzed using descriptive statistics and multivariate modeling. Kaplan-Meier analysis will assess PSA progression-free survival. Subgroup analyses will explore the impact of prior radiation type and treatment volume. The estimated 95% confidence interval for the primary endpoint allows for adequate detection of clinically significant toxicity rates.

CONCLUSIONS

FocaSaBra is a prospective trial to assess FsBT in radiorecurrent PC. It addresses a critical gap in salvage treatment options by potentially offering effective local control with minimal toxicity. Findings from this study may establish FsBT as a viable alternative to whole-gland salvage approaches.