Risk factors for benign proliferative breast disease

Background As part of a nested case-control study of benign proliferative breast disease (BPBD) conducted within the cohort of women participating in the Alberta breast screening programme, an analysis of all women who had a benign breast biopsy between 1990 and 1995 was undertaken to identify the epidemiological risk factors for BPBD. Methods The breast biopsies of all eligible women were re-reviewed by a panel of four pathologists using Page's classification for benign breast disease. Cases were 165 women whose biopsies, upon review, showed benign breast tissue changes ranging from sclerosing adenosis to atypical ductal hyperplasia. Controls were 217 women whose biopsies showed no evidence of any proliferative or neoplastic changes. In-person interviews were conducted with all study subjects. Results Women with greater than or equal to 25% fibroglandular breast tissue density, as compared to women with <25% density, experienced nearly a doubling in risk of BPBD (OR = 1.91, 95% CI : 1.24-2.94). All other possible risk factors examined were not associated with BPBD. Conclusion This study suggests that fibroglandular tissue density may be a risk factor, or marker, for increased risk of BPBD.