RISK OF BREAST-CANCER ASSOCIATED WITH ATYPICAL HYPERPLASIA OF LOBULARAND DUCTAL TYPES

Epidemiological studies Ising the histological classification of Page for benign breast disease consistently demonstrate a positive associat ion between atypical hyperplasia and the subsequent development of bre ast cancer, However, atypical hyperplasia is of either lobular or duct al types, and breast cancer risk in relation to type of atypical hyper plasia has not been studied extensively, Thus, we investigated prospec tively the risk of breast cancer associated with histological subtypes of benign proliferative breast disease, including the types of atypic al. hyperplasia, among participants in the Nurses' Health Study who ha d biopsy-confirmed benign breast disease, Women who subsequently devel oped breast cancer were matched by year of birth and year of biopsy to participants who were free from breast cancer, Benign biopsy slides w ere classified according to the criteria of Page. Odds ratios (ORs) of breast cancer and 95% confidence intervals (CIs), adjusted for the ma tching variables and other breast cancer risk factors, were computed u sing unconditional logistic regression,vith benign nonproliferative br east disease as the referent group, Atypical ductal hyperplasia (OR = 2.4; 95% CI, 1.3-4.5) or atypical lobular hyperplasia (OR = 5.3; 95% C I, 2.7-10.4) in a prior biopsy were associated with increased breast c ancer risk, Atypical lobular hyperplasia was more strongly associated, vith the risk of premenopausal breast cancer (OR = 9.6; 95% CI, 3.3-27 .8) than with the risk of postmenopausal breast cancer (OR = 3.7; 95% CI, 1.3-10.2), The association of atypical ductal hyperplasia and brea st cancer risk varied little by menopausal status. The magnitude of br east cancer risk seems to vary according to the type of atypical hyper plasia present at biopsy.