Two cases of polycystic ovary syndrome with onset of severe ovarian hyperstimulation syndrome following controlled ovarian stimulation with aromatase inhibitors for fertility preservation before breast cancer treatment

The risks of ovarian hyperstimulation syndrome (OHSS) involve high estrogen (E2) levels. We report two breast cancer patients with polycystic ovarian syndrome who underwent fertility preservation and had severe OHSS; their E2 levels were lowered using aromatase inhibitors (AI). A 36-year-old woman underwent controlled ovarian stimulation (COS) with AI and cryopreserved 10 blastocysts. She was hospitalized with OHSS (E2 = 139.1 pg/mL). She improved with infusion alone. A 31-year-old woman underwent COS with AI and cryopreserved 8 blastocysts. She was hospitalized for OHSS (E2: 429 pg/mL). Her vascular endothelial growth factor (VEGF) levels were high (62 pg/mL) at 8 days after the procedure. She needed hospitalization for 9 days. The planned adjuvant therapy was delayed for a week in both cases. Elevated VEGF levels should be considered as a risk factor of OHSS even if E2 levels are low with AI treatment.