What is oligoprogression?-a narrative review

Modern systemic therapies have transformed metastatic cancer management, yet acquired resistance remains a persistent clinical challenge. Frequently, this resistance manifests as oligoprogression, a distinct biological state in which a limited number of metastatic lesions grow or newly develop during active systemic therapy. Driven by branching clonal evolution, these rogue lesions can seed further widespread dissemination. This review examines how oligoprogression is defined and classified, which biological mechanisms underlie it, what clinical evidence supports local ablative therapy (LAT), and which endpoints and selection tools are required to validate the concept.

Relevant English-language literature was identified through a search of PubMed/MEDLINE, supplemented by ClinicalTrials.gov and backward citation screening, covering the period from database inception to June 22, 2026. Prospective and, where available, randomized trials were prioritized, while consensus documents and selected retrospective and translational studies were included according to relevance and informative value.

Historically, focal progression prompted an immediate switch to next-line systemic treatments, which are often more toxic and less effective. However, a paradigm shift is underway: rather than discarding a largely successful regimen, clinicians increasingly utilize metastasis-directed therapy (MDT), such as stereotactic body radiation therapy (SBRT), to locally ablate progressive sites. Continuing effective systemic therapy while ablating resistant sites aims to safely extend its therapeutic window. Recent prospective trials suggest that SBRT may prolong progression-free survival (PFS) in selected settings, with outcomes varying substantially according to tumor histology and disease biology.

LAT is a reasonable option in carefully selected patients, but the benefit depends on tumor histology, the systemic treatment context, and the endpoint assessed. Before oligoprogression can be regarded as an established clinical entity, trials should report PFS after subsequent therapy, time to next systemic therapy (TTNST), toxicity, and patient-reported outcomes (PROs) as distinct measures, and should evaluate imaging- and biomarker-based patient selection prospectively.