Molecular pathology of pre-invasive breast disease in the screening setting: application in diagnosis and management

Mammographic screening programs were introduced to improve outcomes for women with breast cancer by detecting small, early stage tumours. Although endocrine therapy has played a significant role in decreasing mortality, there can be little doubt that early detection has also contributed to the reduced mortality rates seen for breast cancer patients in recent years. An important side-effect of mammographic screening is that it has also identified atypical proliferative, borderline and pre-invasive lesions with increasing frequency. The difficult histological diagnosis of these lesions and their uncertain risk of progression to invasive disease presents considerable clinical difficulties. We present a review of the molecular pathology of common pre-invasive lesions of the breast particularly discussing diagnosis on needle core biopsy, their risk of progression, and clinical management following their mammographic detection.