537 FERTility sparing treatment in patients with ENdometrial Cancer (FERT-ENC) from the Spanish Investigational Network Gynecologic Oncology Group

Introduction/Background* The primary objective was to evaluate the response rate of conservative treatment in endometrial cancer and the secondary objective was to assess oncological, fertility and obstetric outcomes in fertility preservation patients Methodology This was a multi-centre, observational, retrospective study of endometrial cancer patients who underwent fertility-sparing treatment in Spanish centres (January 2010–2020). Seventy-three patients with stage IA, endometrioid adenocarcinoma of the uterus were included in the study. Result(s)* The levonorgestrel intrauterine device (LNG-IUD) was the most used method (53.4%), followed by megestrol acetate (20.5%) and medroxyprogesterone acetate (16.4%). During the 24-month follow-up, the rate of complete response to the fertility-sparing management was 74% (n = 54/73) and 8.2% (n = 6/73) patients presented a partial response. Additionally, 13 (17.8%) patients presented with persistent disease and six (8.2%) patients relapsed after response. The use of LNG-IUD was associated with a higher complete response rate (LNG-IUD 87.2% vs. others 58.8%; p = 0.01). Surgical treatment (at least hysterectomy) was completed in 44 (60.3%) patients. Four (5.5%) patients presented with relapse after surgery being associated with it the final stage FIGO III (p = 0.036), myometrial invasion > 50% (p = 0.018), and final tumour grade 2–3 (p = 0.018). The mean follow-up was 57.8 (range 6–159) months. The five-year relapse-free survival and overall survival were 92.6% (95% CI: 81.3–97.2%) and 93.5% (95% CI: 80.7–97.9%), respectively. The rate of pregnancy was 81.1% (n = 30/37), using, in most cases, reproductive techniques (78.4%) for this purpose. Conclusion* Fertility-sparing management presents a high response rate in endometrial cancer . The use of LNG-IUD associates a better response rate, when compared to other treatment options. Moreover, pregnancy can be achieved with this management by use of reproductive techniques.