Early outcomes of partial gland (focal) salvage brachytherapy for radiorecurrent prostate cancer.

PURPOSE: Whole gland brachytherapy is an effective treatment for radiorecurrent prostate cancer. Partial gland (focal) treatment may provide equal efficacy with an improved toxicity profile for appropriate patients.

METHODS AND MATERIALS: We conducted a retrospective review of 100 patients who underwent focal HDR (19 Gy/1, HDR1; 22 Gy/2, HDR2) or LDR (Pd-103) brachytherapy between January 2017 and December 2024. All patients had prostate biopsies and the majority had MRI and/or PET imaging. ADT was used in 57 patients. Patients were followed with PSA, toxicity, and quality of life assessments. Nadir + 2 definition was used for biochemical failure (BF). Biochemical progression-free survival (bPFS), local failure-free survival (LFFS), toxicities, and quality of life were compared using Kaplan-Meier, Cox regression, and Chi-squared analyses. The median follow-up for the entire cohort was 26.5 months.

RESULTS

The 3-year bPFS (95% CI) for the HDR1, HDR2, and LDR cohorts were 72.3% (60.0-87.1), 84.0% (64.9-100), and 50% (12.5-100), respectively. On multivariate analyses, the only significant predictor for bPFS was presalvage PSA (p = 0.03). Local failure was only seen in the HDR1 cohort during the follow-up period. Grade 3+ GU and GI toxicities at 2-years for the entire cohort were 4.0% (0.0-8.5) and 2.8% (0.0-6.6), respectively.

CONCLUSIONS

Focal brachytherapy provides excellent early outcomes for patients with radiorecurrent prostate cancer. There was no difference in bPFS by brachytherapy type. There were no local failures in the HDR2 and LDR cohorts; however, follow up was short.