Atypical lobular hyperplasia as a unilateral predictor of breast cancer risk: a retrospective cohort study

Clinical decisions about atypical lobular hyperplasia are based on the belief that later invasive breast-cancer risk is equal in both breasts. We aimed to show laterality and subsequent risk implications of invasive breast cancer in women with atypical lobular hyperplasia. We did a retrospective cohort study of 252 women who had undergone 261 benign surgical biopsies that showed atypical lobular hyperplasia from 1950 to 1985, as part of the Nashville Breast Studies. Primary outcomes were development of invasive breast cancer and laterality of cancer compared with side of the biopsied breast. 50 (20%) of 252 women treated by biopsy only developed invasive breast cancer. Relative risk of breast cancer in women with atypical lobular hyperplasia was 3·1 (95% CI 2·3–4·3, p