Clinical Outcomes of Metastasis-directed Therapy for Oligo-metastatic Prostate Cancer Diagnosed Using PSMA-PET/CT or Whole-body MRI.

Objective: Data on clinical outcomes in Japanese patients following metastasis-directed therapy (MDT) for oligo-metastatic prostate cancer (PCa) diagnosed using next-generation imaging modalities [prostate-specific membrane antigen-targeted positron emission tomography/computed tomography (PSMA-PET/CT) or whole-body diffusion-weighted magnetic-resonance imaging (WB-MRI)] are limited.

Methods: We retrospectively evaluated clinical outcomes in patients with oligo-metastatic PCa diagnosed using PSMA-PET/CT or WB-MRI and subsequently treated with MDT between February 2018 and June 2023 at our institution.

Results: In total, 26 patients were analyzed: 14 with hormone-sensitive PCa (oligo-recurrence) and 12 with castration-resistant PCa (oligo-progression). The median patient age was 74 years at the time of diagnosing oligo-metastasis. A total of 30 sites were irradiated. The median prescribed dose was 62.4 Gy in 31 fractions for sites treated with conventional fractionated or moderately hypo-fractionated external-beam radiation therapy (EBRT), and 35 Gy in five fractions for those treated with stereotactic body radiation therapy (SBRT). Systemic therapies were administered in 88.5%. The median follow-up period after the diagnosis of oligo-metastasis was 34.2 months. The overall survival, biochemical failure-free survival, and clinical failure-free survival rates were 94.1, 48.7, and 55.4% at three years, respectively. The local control rate of MDT sites was 96.7%. Grade 2 MDT-related toxicities were observed in 7.6%, whereas no ≥ grade 3 toxicities were reported.

Conclusions: MDT for oligo-metastatic PCa diagnosed using next-generation imaging modalities in a Japanese population can result in favorable disease-free and survival outcomes with acceptable morbidities.