Clinical relevance of circulating ESR1 mutations during endocrine therapy for advanced hormone-dependent endometrial carcinoma.

Objective: Endocrine therapy is frequently administered in patients with hormone dependent (HR+) metastatic endometrial cancer. ESR1 mutations have emerged as a key mechanism of aromatase inhibitor (AI) resistance in HR + metastatic breast cancer and can be monitored using circulating tumor DNA (ctDNA). The aim of this study was to explore the incidence and clinical relevance of circulating ESR1 mutations in patients treated by AI or megestrol acetate (M) for advanced endometrial carcinoma.