Background: Everolimus plus exemestane is approved for the treatment of hormone receptor-positive metastatic breast cancer (MBC) after progression on nonsteroidal aromatase inhibitors. The role of everolimus is less well defined in other breast cancer phenotypes and in combination with other drugs.Objectives: We conducted a systematic review and meta-analysis to assess the efficacy and safety of adding everolimus to standard of care (SoC) in MBC regardless of tumor phenotype and treatment type. Methods: The electronic databases PubMed and EMBASE were searched for eligible randomized trials. Pooled hazard ratios (HRs) for progression-free survival (PFS) and overall survival (OS) and pooled risk ratios (RR) and odds ratios for objective response rates, disease control rate (DCR), and grade 3 or higher toxicity were meta-analyzed. Subgroup analyses compared survival outcomes by tumor phenotype.Results: Data from 2826 patients from eight trials were analyzed. The addition of everolimus to SoC reduced the risk of disease progression by 29% (HR 0.71; 95% confidence interval [CI] 0.56-0.90). This did not translate into an OS benefit (HR 0.95; 95% CI 0.80-1.13). In addition, everolimus improved the DCR (RR 0.82; 95% CI 0.68-0.98), whereas it increased the risk of developing grade 3 or higher toxicity. The PFS benefit was more prominent for patients with hormone receptor-positive (+)/human epidermal growth factor receptor 2 (HER2)-negative (-) disease. For the HER2 (+) subgroup, the PFS benefit was restricted to patients with hormone receptor (-) disease.Conclusions: Everolimus reduces the risk of disease progression in hormone receptor (+) MBC. In patients with HER2 (+) disease, the benefit is limited for those with hormone receptor (-) disease. Given the approval and use of newer drugs in MBC, clinical trials and real-world data are needed to confirm the benefit of everolimus and define the best treatment sequence strategy to adopt in that setting.