Clinical value of circulating ESR1 mutations for patients with metastatic breast cancer: a meta-analysis

Background The clinical implication of plasma ESR1 mutations in the estrogen receptor (ER)-positive metastatic breast cancer (MBC) patients who had progressed after prior aromatase inhibitor (AI)-based therapy remains controversial. We conducted the first meta-analysis to investigate the prognostic significance and predictive role of plasma ESR1 mutations in MBC patients with prior exposure to AI therapy. Materials and methods We searched PubMed, Embase, and Cochrane Library databases for eligible studies. Meta-analysis was conducted to calculate combined hazard ratios (HRs) with 95% CIs for progression-free survival (PFS) and overall survival (OS). Subgroup and sensitivity analyses were also performed. Results This study enrolled a total of 1,530 patients with ER-positive MBC cases from six articles, including 429 ESR1 mutation carriers (28.04%). Meta-analysis demonstrated that plasma ESR1 mutation carriers had significantly worse PFS (HR: 1.40, 95% CI: 1.17–1.66; P