Update on the oncologic and obstetric outcomes of medroxyprogesterone acetate treatment for atypical endometrial hyperplasia and endometrial cancer.

Aims: To evaluate the safety and effectiveness of high-dose oral medroxyprogesterone acetate (MPA) therapy as a fertility-sparing treatment for patients diagnosed with atypical endometrial hyperplasia (AEH) and endometrioid carcinoma G1 without myometrial invasion (G1EC). Particular attention was given to the extended administration and readministration of MPA for patients with persistent disease following initial treatment and those with recurrence.

Methods: We conducted a retrospective analysis of data from 79 patients who underwent daily oral MPA treatment between 2005 and 2024 at Nagoya University Hospital. Patient characteristics, treatment outcomes, factors contributing to recurrence, and post-MPA therapy pregnancies were examined.

Results: MPA therapy achieved a remarkable complete response (CR) rate of 91.1%. The median time to achieve CR was 26.0 and 40.0 weeks for AEH and G1EC patients, respectively. Importantly, 27 patients (39.7%) attained CR after more than 6 months of treatment, including 8 patients (11.8%) who achieved CR after more than a year of treatment. The recurrence rates were 52.9% for AEH and 64.7% for G1EC. Twenty eight patients resumed MPA treatment, and 23 achieved second CR. Notably, recurrence was not associated with clinical factors such as age, body mass index, or post-CR pregnancy. Among patients who attempted pregnancy after achieving CR, 22 live births were successfully achieved.

Conclusions: High-dose oral MPA therapy demonstrated both safety and efficacy for preserving fertility in patients with AEH and G1EC, resulting in a high CR rate. MPA extension and readministration proved to be beneficial strategies for managing patients with recurrence and persistent disease following initial treatment.