Recurrent Serous Borderline Tumor After Fertility-Sparing Surgery Following Twin Pregnancy and Resumption of Menstruation.

Gynecologic malignancies sometimes affect women before menopause. Aggressive treatments, such as surgery, chemotherapy, and/or radiotherapy, often lead to premature menopause. Hormone replacement therapy (HRT), typically used for managing menopause-associated health issues, may be limited by tumor sensitivity to estrogen. Here, we present a case of a 37-year-old woman seeking fertility, who was diagnosed with a serous borderline ovarian tumor (BOT). Fertility-preserving surgery and in-vitro fertilization resulted in a twin pregnancy. During a postpartum amenorrheic period, there was no recurrence. However, she experienced a rapid recurrence of the disease following the resumption of menstruation and underwent radical surgery. This rapid recurrence after menstruation resumed suggests potential estrogen sensitivity. Close postoperative monitoring has been ongoing without HRT.