Risk factors for benign proliferative breast disease

Background As part of a nested case-control study of benign proliferative b reast 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 e pidemiological risk factors for BPBD. Methods The breast biopsies of all eligible women were re-reviewed by a pan el of four pathologists using Page's classification for benign breast disea se. Cases were 165 women whose biopsies, upon review, showed benign breast tissue changes ranging from sclerosing adenosis to atypical ductal hyperpla sia. Controls were 217 women whose biopsies showed no evidence of any proli ferative or neoplastic changes. In-person interviews were conducted with al l study subjects. Results Women with greater than or equal to 25% fibroglandular breast tissu e density, as compared to women with <25% density, experienced nearly a dou bling in risk of BPBD (OR = 1.91, 95% CI : 1.24-2.94). All other possible r isk 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.