The patho-epidemiology of benign proliferative epithelial disorders of the female breast.

Benign breast disease is associated with increased risk of subsequent breast cancer, especially when there is evidence of epithelial proliferation. There is no standard terminology for benign proliferative epithelial disorders (BPED), and this hinders direct comparisons between the various studies which have examined their pathology and their relationship to breast cancer. The present paper reviews previous classification schemes for BPED, and proposes an alternative system in which epitheliosis and blunt duct adenosis are the major features, the degree and pattern of the hyperplasias being graded separately. Adoption of this or a similar system as a standard should facilitate future comparative studies of these conditions. As BPED are apparently pre-malignant conditions, an understanding of their aetiology is important because it may help to elucidate the aetiology of breast carcinoma, and to open up avenues for its prevention. If BPED are precursors to breast carcinoma, then risk factors for BPED should also be risk factors for breast carcinoma. To date, in epidemiological studies of BPED, such concordance has not been demonstrated, as consistent risk factors for the BPED have not yet emerged. This may have resulted, at least in part, from differences in the histological categories included in the various studies. Therefore, collaboration between epidemiologists and pathologists may facilitate progress towards an understanding of BPED.