Risk factors for benign breast biopsies: a nested case-control study in the Alberta breast screening program

A nested case-control study was conducted to identify risk factors for benign breast biopsies in 382 cases (women with a benign biopsy result) and 399 controls (women who had not undergone a biopsy) who were sampled from the Alberta breast cancer screening program. The breast biopsy specimens of the cases were reviewed by a panel of pathologists, and percent fibroglandular tissue density was assessed. The multivariable odds ratios for the risk of open benign breast biopsy associated with current cigarette smoking was 2.04 (95% CI 1.32-3.13), for ever regular smoking was 1.61 (1.20-2.16), and for passive smoking was 1.41 (0.99-2.02). A risk reduction was found for ever alcohol consumption (0.61 [0.44-0.85]). Some risk reductions were found when the highest and the lowest quintiles of total aerobic recreational activity were compared (0.71 [0.42-1.20]), stair climbing (0.61 [0.37-1.01]) and walking pace (0.13 [0.02-0.741). Lifestyle risk factors may be implicated in the continuum between detection of an abnormality on a screening mammogram and a breast biopsy specimen. By considering these risk factors, breast screening programs may be better able to identify those women who require a breast biopsy and reduce the number of benign breast biopsies.