PSMA PET-Guided Progression-Directed Radiotherapy for Oligoprogressive Prostate Cancer (PSMA-OLIGO-PRO)

PSMA-OLIGO-PRO is a multicenter ambispective observational real-world evidence registry of patients with prostate cancer who develop limited oligoprogression during otherwise active systemic therapy and undergo lesion-directed radiotherapy in routine clinical practice. The study includes retrospective data from patients treated before June 26, 2026 and prospective data from patients enrolled from June 26, 2026 onward.

Oligoprogression is defined as the occurrence of up to five new and/or regrowing lesions detected on PSMA PET/CT or PSMA PET/MR while other known disease sites remain controlled under ongoing systemic therapy. MRI may be used as a complementary imaging modality when clinically appropriate, especially for intraprostatic recurrence, local recurrence, or prostate-bed progression. Oligoprogression will be categorized according to the ESTRO/EORTC oligometastatic disease framework, including metachronous oligoprogression, repeat oligoprogression, and induced oligoprogression.

Participants are not assigned to any intervention by the registry protocol. The registry does not mandate imaging, systemic therapy, radiotherapy, dose, fractionation, target definition, treatment planning, or follow-up schedules. All clinical decisions are made by treating physicians according to institutional standards, multidisciplinary assessment, available imaging, patient condition, previous treatment history, and local practice.

The exposure of interest is PSMA PET-guided progression-directed radiotherapy delivered with ablative or definitive local intent to all identifiable oligoprogressive lesions. Radiotherapy may include stereotactic body radiotherapy for nodal, bone, visceral, or selected local lesions; moderately hypofractionated external beam radiotherapy when clinically selected; and high-dose-rate or other brachytherapy approaches when appropriate. Brachytherapy may be considered for intraprostatic or prostate-bed oligoprogressive recurrence and, in selected cases, for technically suitable metastatic lesions such as liver metastases, according to institutional expertise and clinical judgment.

The study population includes patients with metastatic hormone-sensitive prostate cancer or metastatic castration-resistant prostate cancer who are receiving active systemic therapy at the time of oligoprogression. Systemic therapy may be continued, modified, or escalated according to routine clinical decision-making. The registry is designed to evaluate whether local treatment of all oligoprogressive lesions can prolong benefit from the current systemic therapy line, delay the need for systemic treatment escalation, and preserve the oligometastatic state.

The primary endpoint is time to next systemic therapy escalation, defined as the time from the start of the index progression-directed radiotherapy course to initiation of a new systemic therapy line. Key secondary endpoints include time to polymetastatic progression, radiographic progression-free survival, overall survival, local control of treated lesions, repeat oligoprogression, use of subsequent lesion-directed therapy, patterns of disease progression, and treatment-related adverse events.

Safety will be assessed using adverse events recorded in routine clinical care and graded according to CTCAE version 5.0 when sufficient information is available. Acute and late adverse events will be described separately. Exploratory analyses will evaluate clinical, imaging, disease-related, and treatment-related factors associated with delayed systemic therapy escalation, durable local control, and preservation of an oligometastatic disease state.

Because this is an observational registry, the study aims to describe real-world outcomes after contemporary PSMA PET-guided progression-directed radiotherapy rather than test a protocol-assigned treatment strategy. The results are intended to support patient selection, multidisciplinary decision-making, and future prospective studies of oligoprogressive prostate cancer.