Postoperative radiotherapy for stage IV breast cancer following primary tumor removal: Systematic review and meta-analysis

De novo metastatic breast cancer (dnMBC) is diagnosed when breast cancer has spread at presentation and accounts for 5–10% of cases. The benefit of postoperative radiotherapy (PORT) after primary tumor surgery in this setting remains uncertain.

We conducted a review and meta-analysis of observational studies published between 2013 and 2024. Two databases (PubMed and Embase) were searched and the review followed PRISMA 2020 guidelines. The aim was to evaluate whether PORT improves overall survival (OS) in dnMBC patients undergoing surgery. The PICOTS framework was applied. Studies were eligible if they compared surgery with or without PORT. OS was analyzed at three and five years as a binary outcome. The study was not registered prospectively.

Five studies were included qualitatively; three were eligible for quantitative synthesis (N=8,557). PORT was associated with improved OS at three years (OR=0.62; 95% CI: 0.56–0.68) and five years (OR=0.65; 95% CI: 0.60–0.71). Benefits were most evident in patients with bone-only metastases and luminal A tumors. No consistent survival advantage was seen in HER2+ or triple-negative disease.

PORT may offer a survival advantage for selected dnMBC patients undergoing surgery. Further prospective studies are needed to confirm these findings and define optimal candidates.