Endocrine Therapy for Primary and Secondary Prevention After Diagnosis of High-Risk Breast Lesions or Preinvasive Breast Cancer.

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology , to patients seen in their own clinical practice. Patients with high-risk breast lesions (HRLs) or preinvasive breast cancers face an elevated risk of future breast cancer diagnoses. Endocrine therapy in this setting reduces the risk of a future diagnosis but does not confer improved survival, thus the side effects of primary/secondary prevention must be considered relative to the benefits. Here, we discuss the available chemoprevention regimens for patients with HRLs and considerations for selecting a regimen, as well as the decision making surrounding use of adjuvant endocrine therapy for patients with ductal carcinoma in situ (DCIS). For patients with HRLs, available chemoprevention regimens differ by menopausal status, including tamoxifen 20 mg once daily for 5 years and more recently tamoxifen 5 mg once daily for 3 years in both premenopausal and postmenopausal women as well as raloxifene or aromatase inhibitors for postmenopausal women. We recommend a shared decision-making approach with attention to patient preferences related to risk tolerance and side-effect profiles. Low-dose tamoxifen appears to be a particularly favorable choice that is well tolerated, without risk of serious adverse events and offers comparable risk reduction to other regimens. For DCIS, the benefit of endocrine therapy in addition to radiation is small, and appears to be driven mainly by a reduction in contralateral breast diagnoses or new breast cancers. A strategy that reduces the side-effect profile of chemoprevention such as low-dose tamoxifen may be especially appealing in the setting of secondary prevention.