The addition of metformin to progestin therapy in the fertility-sparing treatment of women with atypical hyperplasia/endometrial intraepithelial neoplasia or endometrial cancer: Little impact on response and low live-birth rates

Objective: Our objectives were 1) to compare the efficacy of progestin therapy combined with metformin (Prog-Met) to Prog alone as primary fertility sparing treatment in women with atypical hyperplasia/endometrial intraepithelial neoplasia (AH/EIN) or early-stage endometrioid carcinoma (EC), and 2) to analyze the proportion of women achieving live birth following treatment. Methods: A retrospective cohort study of all reproductive-aged women with AH/IN or EC treated with Prog ± Met from 1999–2018 was conducted. Complete response (CR) was assessed and Kaplan-Meier analysis used to calculate time to CR. Comparison of potential response predictors was performed with multivariable Cox regression models. Results: Ninety-two women met criteria; 59% (n = 54) were treated for AH/EIN and 41% (n = 38) for EC. Their median age, body mass index, and follow up time was 35 years, 37.7 kg/m², and 28.4 months, respectively. Fifty-eight women (63%) received Prog and 34 (37%) received Prog-Met. Overall, 79% (n = 73) of subjects responded to treatment with a CR of 69% (n = 63). There was no difference in CR (p = 0.90) or time to CR (p = 0.31) between the treatment cohorts. Overall, 22% experienced a disease recurrence. On multivariable analysis, EC histology was the only covariate associated with a decreased Prog response (HR 0.48; p = 0.007). Only 17% of the cohort achieved a live-birth pregnancy, the majority of which required assisted reproductive technologies (81%) and occurred in the Prog treatment group. Conclusions: Our study does not support the use of Prog-Met therapy for treatment of AH/EIN or EC. Additionally, fewer than 20% of women achieved a live-birth pregnancy during the study period, with most requiring ART.