PSMA PET-Staged Comprehensive Progression-Directed Radiotherapy for Limited Progression in Prostate Cancer

PSMA-OLIGO-PRO is a multicenter, ambispective, observational real-world evidence registry of adults with metastatic hormone-sensitive or metastatic castration-resistant prostate cancer who develop a limited number of progressing metastatic lesions during active systemic therapy and are considered for comprehensive progression-directed radiotherapy (PDRT) in routine clinical care. The registry includes retrospective cases treated before June 26, 2026, and prospective cases enrolled from June 26, 2026, onward. Before the site-specific protocol amendment takes effect, the metastatic-lesion ceiling is 1-5. After the amendment takes effect, prospective candidates with 1-10 qualifying progressing metastatic lesions on baseline PSMA PET/CT or PSMA PET/MRI may be included. Metastatic burden is prespecified as 1-5 lesions, representing classical oligoprogression, or 6-10 lesions, representing exploratory, PSMA PET-defined, limited progression. Intraprostatic and prostate-bed progressing foci are recorded separately from the metastatic count and must also be included in the comprehensive PDRT plan. Otherwise eligible local-only episodes form a separate descriptive stratum. All qualifying metastatic and locally progressing sites must be deemed technically amenable to definitive-intent PDRT before prospective analytic-cohort enrollment. The registry does not assign imaging, systemic therapy, or radiotherapy; these clinical decisions are made independently by the treating team in routine care. A qualifying baseline PSMA PET and documentation of comprehensive treatability are required for inclusion. The primary endpoint is time to next systemic therapy in the continuation-plan treatment-start set. Key secondary outcomes include PDRT initiation and comprehensive implementation, time to widespread or non-PDRT-amenable progression, classical time to polymetastatic progression in the baseline 1-5 cohort, radiographic progression-free survival, lesion-level local control, overall survival, and treatment-related toxicity. The prespecified 1-5 versus 6-10 comparison is restricted to concurrent post-amendment prospective participants and is exploratory.