Objective Fertility preservation is an option for selected patients with endometrial hyperplasia or cancer. This study aimed to evaluate whether duration of treatment impacts the oncologic and reproductive outcomes.

Methods We retrospectively reviewed patients diagnosed with endometrial cancer/atypical endometrial hyperplasia who underwent fertility-sparing treatment from January 2012 to December 2016. As the duration of treatment required by the patients was different, the patients who achieved a complete response were grouped according to the treatment duration as groups A (≤6 months), B (6–9 months), and C (>9 months).

Results With the prolongation of treatment duration from 6 months to 9 months to >9 months, the accumulative complete response rates for 67 patients were 58%, 76%, and 95.5%, respectively. Among groups A, B, and C there was no significant difference in the relapse rates (21.1%, 25%, and 36.4%, respectively, p=0.60) or the median time interval to relapse (14, 13, and 13.5 months, respectively, p=0.90). Maintenance treatment was an independent protective factor for recurrence (p=0.001), while the complication of diabetes was an independent risk factor for recurrence (p=0.03). Fertility rates (31%, 18.2%, and 62.5%, respectively, p=0.12) and the time interval to pregnancy (14, 13, and 8 months, respectively, p=0.67) were not significantly different among the three groups. Assisted reproductive technology was positively associated with a higher pregnancy rate (p=0.02) and a body mass index ≥25 kg/m² was negatively associated with the pregnancy rate (p=0.047).

Conclusions Longer treatment duration was associated with higher rates of complete response. Longer treatment duration (>9 months) was not associated with a decrease in success rates of pregnancy.