Oligometastatic Prostate and Bladder Cancer: An Integrative Narrative Review.

This narrative review synthesizes contemporary evidence and provides practical guidance for oligometastatic prostate cancer (OMPC) and oligometastatic bladder cancer (OMBC), focusing on image-guided patient selection and integrating metastasis-directed therapy (MDT). In OMPC, phase II randomized trials show that consolidating all imaging-visible lesions-most commonly with stereotactic body radiotherapy (SBRT)-prolongs progression-free survival, delays systemic therapy escalation, and extends both androgen deprivation therapy-free and eugonadal progression-free survival. This is achieved with low severe toxicity rates with organ-at-risk dose constraints. Elective nodal radiotherapy enhances regional control of pelvic nodal recurrence, and MDT can be layered onto modern systemic backbones in the metachronous oligometastatic, synchronous oligometastatic and oligoprogressive settings, provided that complete lesion ablation is feasible. Prostate-specific membrane antigen (PSMA) PET/CT is pivotal for staging and restaging, while whole-body diffusion-weighted MRI serves as a complementary tool for assessing disease activity, particularly in treated bone metastases. In OMBC, MDT is most appropriately considered a consolidation strategy for patients with near-complete response and few technically amenable residual lesions, or to control oligoprogression, allowing an otherwise effective systemic regimen to be maintained. While prospective and retrospective data support high local control rates, robust, disease-specific randomized evidence of survival benefit remains limited. In both diseases, successful outcomes hinge on harmonized definitions, explicit lesion enumeration, adherence to dose-volume constraints for ablative techniques, and patient-centered endpoints. Future priorities include developing biologically informed patient selection criteria, standardizing imaging and reporting protocols, and conducting randomized trials to quantify the incremental benefit of MDT beyond contemporary systemic therapy.