Successful management of an ovarian enlargement resembling ovarian hyperstimulation in a premenopausal breast cancer patient receiving tamoxifen with cotreatment of GnRH-agonist.

Tamoxifen use in breast cancer patients may cause ovarian cysts. This report presents a case of complex cyst resembling ovarian hyperstimulation in a premenopausal breast cancer patient receiving tamoxifen which resolved by administering monthly depot GnRH-agonist (GnRH-a) without abandoning the tamoxifen treatment.