Long-term control for > 9 years with megestrol acetate-letrozole: metastatic endometrioid carcinoma case report

Background Hormone receptor–positive (HR+) endometrial carcinoma (EC) responds to endocrine therapy, but clinical benefit duration is often limited, especially in patients with widely metastatic or recurrent disease. Case A 54-year-old woman with HR-high (ER/PR 90%) metastatic EC (FIGO IIIC2) discontinued adjuvant chemotherapy due to severe toxicity. She initiated megestrol acetate and letrozole in March 2017, achieving stable disease (SD) for 38 months. Self-discontinuation (January–July 2020) led to disease progression (new retroperitoneal lymph nodes), but resuming full-dose therapy restored SD for 49 months. After dose reduction (July 2023), the disease progressed again at 12 months; re-escalation to full dose induced regression. At last follow-up (OS: 108 months), she maintained SD with minimal toxicity. Conclusion This is the first case demonstrating that full-dose megestrol acetate plus letrozole may induce durable antitumor activity in HR-high expression metastatic EC, warranting prospective validation.