TY - JOUR T1 - EP667 fertility preservation in breast cancer: the protective role of letrozole JF - International Journal of Gynecologic Cancer JO - Int J Gynecol Cancer SP - A386 LP - A386 DO - 10.1136/ijgc-2019-ESGO.721 VL - 29 IS - Suppl 4 AU - N Chraiet AU - M Braham AU - A Mokrani AU - K Kacem AU - M Hamdoun AU - A Mezlini AU - F Zhioua Y1 - 2019/11/01 UR - http://ijgc.bmj.com/content/29/Suppl_4/A386.1.abstract N2 - Introduction/Background Ovarian stimulation with exogenous gonadotropins increases circulating estrogen levels which might stimulate breast cancer sensitive cells. The use of anti aromatase agents such as letrozole could prevent this elevation and protect patients however, it does not reduce the average number of oocytes or embryos collected.Methodology It’s a prospective study from January 2015 to October 2018. We have compared the number of mature oocytes obtained in patients with breast cancer stimulated by letrozole (Groupe 1) to those collected in patients with other types of cancer (group 2).The stimulation is conducted according to an antagonist protocol with random start and GnRH agonist triggering. For patients with breast cancer, the adjunction of letrozole 5 mg/day was started the first day of the ovarian stimulation and continued 7 days after oocyte pick up.Results We conducted 143 fertility preservation (oocyte/embryo vitrification) with 75 cases in breast cancer.The average age of patients (year) was respectively 30.3±3.7 and 26.9±6.7 with no significant difference (p=0.73). The ovarian reserve was not statistically different: Follicular count AFC (12.3±6.2 vs 13.9±6.4; p=0.7) and Anti Mullerhien Hormone AMH (2.43±2.3 ng/ml vs 2.8±2.45 ng/ml, p=0.5).The estradiol level on the day of ovulation triggering was significantly lower 479±323 pg/ml in the breast cancer group versus 1701±682 pg/ml (p=0.02)The number of CCOs obtained in the breast cancer group was 10.76±8.39 compared with 9.11±6.81 (p=1.83).Conclusion Letrozole as a hormonotherapy in breast cancer, would also allow an efficient ovarian stimulation in women with breast cancer, and safer with a lower estradiol levels.Disclosure Nothing to disclose. ER -