Postmenopausal women with DCIS post-mastectomy: a potential role for aromatase inhibitors

For postmenopausal women with ductal carcinoma in situ (DCIS) where optimal local control or patient preference results in mastectomy, despite substantial risk of contralateral invasive breast cancer, tamoxifen is uncommonly prescribed based on unfavorable risk-benefit consideration. In the National Cancer Institute of Canada Clinical Trial Group (NCIC CTG) MAP.3 primary prevention trial, in postmenopausal women exemestane reduced invasive breast cancer incidence by 65% without increasing life-threatening side effects. In adjuvant breast cancer trials, the aromatase inhibitor exemestane as well as anastrozole and letrozole have all reduced new contralateral breast cancer incidence. Thus, aromatase inhibitors, and perhaps particularly exemestane, provide an option to address the risk of contralateral breast cancer in postmenopausal women with DCIS managed with mastectomy.