Outcome comparison of radical prostatectomy versus seed brachytherapy for clinically localized prostate cancer using two biochemical recurrence definitions

Abstract

Objective: We compared the outcome of radical prostatectomy (RP) with seed brachytherapy (BT) in clinically localized prostate cancer (LPCa) using two different biochemical recurrence (BCR) definitions.

Methods: Clinical data of 1117 patients with non-metastatic prostate cancer (PCa) treated with either RP or BT as the basis of the multimodal therapy from a single tertiary hospital between 2007 and 2021 were retrospectively analyzed. 843 LPCa patients (RP = 737, BT = 106) with at least one prostate-specific antigen (PSA) test after treatment were finally included. The BCR survival was evaluated by direct comparison and one-to-one propensity score matching (PSM) analysis using surgical definition (PSA ≥ 0.2ng/ml) for RP and surgical/Phoenix definition (PSA nadir + 2ng/ml ) for BT. The propensity score (PS) was calculated by multivariable logistic regression based on the clinicopathological parameters.

Results: Median follow-up was 43 months for RP patients and 45 months for BT patients. Kaplan-Meier analysis did not show any statistically significant differences in terms of BCR-free survival (BFS) between the two groups when using Phoenix definition for BT (P > 0.05). Similar results were obtained in all D'Amico risk groups when stratified analyses were conducted. However, RP achieved improved BFS compared to BT in the whole cohort and all risk groups with the surgical definition for BT(P < 0.05). After adjusting PS, 192 patients were divided into RP and BT groups (96 each). RP presented a better BFS than BT when using the surgical definition (P < 0.001), but no significant difference was found when using the Phoenix definition (P = 0.609).

Conclusion: Inconsistent BCR-free survival outcomes were acquired using two different BCR definitions for BT patients. RP provided comparable BFS with BT using the Phoenix definition but better BFS using the surgical definition, regardless of whether the PSM was performed. Our findings indicated that an exact BCR definition was critical for prognostic assessment. The corresponding results will assist physicians in pretreatment consultation and treatment selection.

Keywords: Biochemical recurrence definition; Localized prostate cancer; Radical prostatectomy; Seed brachytherapy.