Outcome after primary directed radiotherapy in predominantly PSMA-PET/CT-staged patients with metastatic prostate cancer.

Abstract

Background: Oligometastatic prostate cancer (OMPC) is typically treated with systemic therapy, which may be complemented by radiotherapy (RT) of the prostate as part of primary directed therapy (PDT). This study retrospectively evaluated clinical outcomes following PDT in OMPC.

Results: Twenty-four consecutive patients who underwent PDT for OMPC between 2011 and 2023 were analyzed retrospectively. The primary endpoint was progression-free survival (PFS); secondary endpoints included biochemical PFS (bPFS), overall survival (OS), and treatment-related toxicity. Survival was estimated using Kaplan-Meier analysis, and prognostic factors for PFS were assessed using univariate log-rank tests and multivariate Cox regression. The median follow-up was 40 months. Median age was 75 years (range: 58-83), with a median of two metastases (range: 1-5). Nineteen patients (79%) were staged with PSMA-PET/CT; 20 had synchronous and 20 low-burden disease (CHAARTED criteria). The most common RT regimen was 60 Gy in 20 fractions. Twenty-three patients received androgen deprivation therapy (ADT), including six with an androgen receptor signaling inhibitor (median duration: 23 months). Additionally, 22 underwent metastasis-directed therapy (MDT), and five elective nodal RT. Median PFS and bPFS were 80 and 73 months, respectively; median OS was not reached. Three-year PFS, bPFS, and OS were 78%, 81%, and 84%. Low metastatic burden (p = 0.007) and synchronous metastases (p = 0.027) predicted longer PFS. No acute grade 3 toxicity occurred; late grade 3 gastrointestinal and genitourinary toxicity occurred in 8% each.

Conclusions: In this predominantly PSMA-PET/CT-staged cohort, PDT combined with MDT and ADT achieved promising long-term outcomes with acceptable toxicity, warranting confirmation in larger prospective studies.