Local therapy is increasingly considered in the multimodal management of oligometastatic prostate cancer (omPCa). This retrospective study compared two primary local treatments—radical prostatectomy (RP) and permanent prostate brachytherapy (PPB)—to evaluate their impact on time to castration-resistant prostate cancer (CRPC) among patients receiving continuous androgen deprivation therapy (ADT). The aim was to provide evidence to inform individualized treatment selection.
Investigators performed a retrospective analysis of 88 consecutive patients treated at a single tertiary center between April 2011 and August 2019. Inclusion criteria identified patients with omPCa, defined in this study as having five or fewer metastatic lesions. All patients underwent either RP (n = 62) or PPB (n = 26) and received continuous ADT thereafter.
To address baseline imbalances between treatment groups, a 1:1 propensity score matching (PSM) procedure was applied. Matching covariates were age at diagnosis, baseline prostate-specific antigen (PSA), clinical T stage (≤T2c vs ≥T3), and nodal status (N0 vs N1). The primary endpoint was time from initiation of ADT to development of CRPC, as defined by PCWG3 criteria. Survival comparisons used Kaplan–Meier analysis with Log-rank testing. Univariate and multivariate Cox proportional hazards models were used to identify independent predictors of progression to CRPC.
Before matching, the two treatment cohorts differed significantly on key prognostic factors: the PPB group was older (mean age 73.2 vs 68.1 years, P = 0.002), had a higher median PSA (31.2 vs 9.8 μg/L, P = 0.002), and a higher rate of lymph node involvement (42.3% vs 12.9%, P = 0.006). After PSM, a balanced matched cohort of 36 patients (18 per treatment arm) was obtained with standardized mean differences for covariates below the reported threshold (SMD < 0.1).
The study’s primary outcome was time to CRPC from the start of ADT. Median follow-up for the combined cohorts was 30.5 months (range 3.2–113.4 months). Kaplan–Meier curves and Log-rank tests evaluated differences in CRPC-free survival between treatment groups. Cox regression was used to calculate hazard ratios (HRs) in both univariate and multivariate models adjusted for clinical T and N stage.
Across the entire cohort, 15 patients (17.0%) progressed to CRPC during follow-up: 8 events in the PPB group and 7 in the RP group. In the pre-matched analysis, RP was associated with a significantly delayed progression to CRPC (Log-rank P = 0.033), with an observed HR = 3.38 (95% CI: 1.10–10.40). The median CRPC-free survival for the PPB group was 80.0 months; the median for the RP group was not reached during follow-up.
After propensity score matching, the survival advantage for RP persisted and was more pronounced: Log-rank P = 0.032 and HR = 4.60 (95% CI: 1.14–18.49). In the matched cohort the PPB median CRPC-free survival remained 80.0 months, while RP again had not reached median CRPC-free survival.
Multivariate Cox regression adjusting for clinical T and N stage identified treatment modality as a strong independent predictor of progression to CRPC. Patients treated with PPB had a higher risk of progression compared with those treated with RP (PPB vs RP HR = 8.56, 95% CI: 1.51–48.64, P = 0.015). Higher primary tumor stage (clinical T3 or greater) was also an independent adverse factor for progression (HR = 10.29, 95% CI: 1.75–60.57, P = 0.010).
In this single-center retrospective cohort of patients with omPCa treated with continuous ADT, radical prostatectomy was associated with a significantly longer delay to castration-resistant prostate cancer compared with permanent prostate brachytherapy. Treatment modality remained an independent prognostic factor after adjusting for T and N stage.
The authors note that these results support considering the type of local therapy when planning multimodal treatment for omPCa and argue the need for prospective randomized trials to confirm the findings and define optimal strategies. The abstract does not report details on treatment techniques, perioperative or radiation-related adverse events, use of metastasis-directed therapy, or subsequent systemic treatments beyond continuous ADT; those details were not available in the source abstract.
All authors declared no conflicts of interest.