Frozen-Thawed Embryo Transfer Outcomes After Fertility-Sparing Treatment for Endometrial Carcinoma

To evaluate the effect of a history of endometrial neoplastic lesions and subsequent fertility-sparing treatment on reproductive outcomes and endometrial response in frozen-thawed embryo transfer cycles.

This retrospective, propensity score-matched cohort study was conducted at a tertiary referral hospital between January 1, 2020, and December 31, 2024. Patients who achieved complete remission of stage IA, grade 1 endometrial carcinoma or endometrial intraepithelial neoplasia were matched 1:1 to patients with infertility in a control group (tubal or male factor) on the basis of age, body mass index (BMI), and infertility type. A total of 126 matched pairs (252 patients) were analyzed. All participants underwent artificial cycles for endometrial preparation followed by blastocyst transfer. Primary outcome measures included the clinical pregnancy rate and live-birth rate in the first frozen-thawed embryo transfer cycle and the cumulative live-birth rate across successive cycles.

In the first frozen-thawed embryo transfer cycle, the study group exhibited significantly lower rates of clinical pregnancy (47/126 [37.3%] vs 77/126 [61.1%], P <.001) and live birth (30/126 [23.8%] vs 60/126 [47.6%], P <.001) compared with the control group. After adjustment for confounders, patients with a history of endometrial neoplastic lesions had significantly lower odds of reproductive outcomes than patients in the control group. Patients with a history of endometrial neoplastic lesions required longer estrogen preparation (median 14 days vs 12 days, P <.001) and achieved higher serum estradiol levels yet demonstrated significantly thinner endometrium at conversion ( P <.001). Kaplan-Meier analysis showed a significantly lower cumulative live-birth rate in the study group (hazard ratio 0.60, 95% CI, 0.40-0.89, P =.012). Within the study cohort, a time to complete remission exceeding 6 months was independently associated with reduced odds of clinical pregnancy (odds ratio 0.50, 95% CI, 0.30-0.85, P =.011).

Histologic remission after fertility-sparing treatment for endometrial carcinoma does not equate to functional endometrial recovery, as evidenced by impaired endometrial development and significantly compromised live-birth rates. These findings highlight the necessity of incorporating endometrial protection into initial oncologic treatments.