Measuring Ovarian Escape in Premenopausal Estrogen Receptor-Positive Breast Cancer Patients on Ovarian Suppression Therapy.

Because up to a quarter of premenopausal women do not attain adequate ovarian suppression within the first 3 months of gonadotropin-releasing hormone (GnRH) agonist therapy, bloodwork should be checked to ascertain hormone levels prior to starting aromatase inhibitor therapy, and at regular intervals, for these women.