Impact of Local Treatment of the Primary Tumor on Overall Survival in <i>De Novo</i> Metastatic Breast Cancer: A Systematic Review and Meta-analysis.

Background/Aim: metastatic breast cancer (dnMBC) remains unclear. We conducted a systematic review and meta-analysis to evaluate whether surgery and/or radiotherapy of the primary tumor improves overall survival (OS). Materials and Methods: , and meta-regression was used to explore potential moderators. Results: =91.5%), these findings need to be interpreted with caution. Subgroup analyses showed a non-significant trend in hormone receptor-positive disease (HR=0.78; 95% CI=0.58-1.04) and no benefit in HER2-positive (HR=0.90; 95% CI=0.61-1.33) or liver-limited disease (HR=1.17; 95% CI=0.77-1.78). No covariates were significantly associated with OS in meta-regression. Conclusion: Although pooled analyses suggest an association between local treatment and improved OS, this effect appears largely driven by retrospective data and is not confirmed in randomized trials.