Association of atypical characteristics of benign breast lesions with subsequent risk of breast cancer

A retrospective case-control study was carried out to determine to what degree atypical changes in the mammary duct system are associated with increased risk of developing breast cancer. A previously developed grading system was used by one of us (MMB) to describe the morphological atypicality in a series of benign breast lesions. Our primary finding is that a woman with some degree of ductular atypia in a benign lesion is subject to a risk of developing breast cancer 5 times that of a woman with no evidence of atypical changes. The implications of this finding regarding treatment require further study.