Prostate Radiotherapy and Metastasis-Directed Therapy in Synchronous Oligometastatic Prostate Cancer

This is an ambispective, multicenter, observational real-world registry of patients with synchronous de novo oligometastatic prostate cancer, defined as prostate cancer with up to 10 extraregional metastatic lesions diagnosed at initial presentation or within 6 months of the primary diagnosis. The study will evaluate outcomes after comprehensive local and metastasis-directed treatment. Eligible patients receive definitive prostate-directed radiotherapy, which may include external-beam radiotherapy, external-beam radiotherapy with brachytherapy boost, or definitive prostate brachytherapy monotherapy in selected patients, together with stereotactic body radiotherapy to all identified extraregional metastatic lesions. Systemic therapy is given according to routine clinical practice and local multidisciplinary decisions. The registry is non-interventional. Participants are not assigned to treatment by the study protocol, and no experimental treatment, randomization, or protocol-mandated imaging schedule is used. The study collects de-identified data from routine medical records, including baseline disease characteristics, imaging, radiotherapy details, systemic therapy, radiographic progression, patterns of failure, subsequent treatments, adverse events, and survival. The study includes historical retrospective data, prospective follow-up of previously treated eligible patients, and prospective enrollment of newly eligible patients from the registry activation date. The main goal is to describe where and when prostate cancer progresses after comprehensive treatment of the prostate and all visible metastatic lesions, and to identify clinical and treatment-related factors associated with disease control and adverse events.

Inclusion Criteria: * Histologically confirmed adenocarcinoma of the prostate. * Male sex. * Age 18 years or older. * Synchronous de novo metastatic prostate cancer diagnosed at initial presentation or within 6 months of primary prostate cancer diagnosis. * Up to 10 extraregional metastatic lesions on staging imaging used for clinical decision-making. * Treatment with definitive prostate-directed radiotherapy, including external-beam radiotherapy alone, external-beam radiotherapy with brachytherapy boost, or definitive prostate brachytherapy monotherapy in selected patients. * Treatment with SBRT or another ablative metastasis-directed radiotherapy approach to all identified extraregional metastatic lesions. * Availability of sufficient clinical, imaging, radiotherapy, systemic therapy, follow-up, adverse event, and survival data for outcome assessment. * For prospectively enrolled patients, ability to provide informed consent where required by local ethics and regulatory procedures. Exclusion Criteria: * More than 10 extraregional metastatic lesions at baseline staging. * Incomplete metastasis-directed therapy, defined as treatment of selected metastatic lesions only while leaving other known baseline extraregional metastatic sites untreated. * Prostate-directed radiotherapy delivered with palliative rather than definitive intent. * Missing key dates preventing outcome determination, including prostate-directed radiotherapy, brachytherapy, metastasis-directed SBRT dates, or follow-up information. * Prior definitive treatment of prostate cancer before diagnosis of synchronous metastatic disease. * Histology other than adenocarcinoma of the prostate.