Aromatase Inhibitors as Adjuvant Therapy for Breast Cancer

Most of the 2.5 million breast cancer survivors in the U.S. are menopausal and had hormone-receptor–positive tumors.1^,2^,3 In recently updated guidelines (JW Womens Health Jul 29 2010), the American Society of Clinical Oncology (ASCO) recommended that adjuvant therapy for postmenopausal women with hormone-receptor–positive breast cancer include an aromatase inhibitor (AI).4 As a result, clinicians who care for menopausal women are encountering more patients who are using AIs (which include anastrozole [Arimidex], letrozole [Femara], and exemestane [Aromasin]).

Mechanism of Action of AIs

In menopausal women, androgens are converted to estrogens by the enzyme aromatase, which is present in adipose and other tissues. By blocking this enzyme, AIs …