Breast density in relation to risk of ductal carcinoma in situ of the breast in women undergoing screening mammography

To examine the association between breast density and risk of breast ductal carcinoma in situ (DCIS).We assessed breast density in relation to DCIS risk using combined data from statewide mammography registries in NH and VT. The prospective analyses were based on 572 DCIS cases arising in 154,936 women (58,496 premenopausal and 96,440 postmenopausal). Women in the study were followed on average 4.1 years. Breast density was scored by community radiologists using BIRADS categories (fatty, scattered density, heterogeneous density, extreme density).In premenopausal women, based on 157 cases, the RR for DCIS risk were 0.29 (95% CI: 0.0.04, 2.24) for fatty breasts, 2.06 (95% CI: 1.39, 3.05) for heterogeneous density, and 2.40 (95% CI: 1.47, 3.91) for extreme density, relative to scattered density. In postmenopausal women, based on 369 cases, the RR for DCIS risk were 0.58 (95% CI: 0.37, 0.93) for fatty breasts, 1.41 (95% CI: 1.12, 1.78) for heterogeneous density, and 1.49 (95% CI: 0.93, 2.37) for extreme density, relative to scattered density. The possible interaction between breast density and menopausal status in relation to DCIS risk was not statistically significant.We observed an association between breast density and DCIS risk. Although the association seemed stronger in premenopausal women, there was no evidence of an interaction involving breast density and menopausal status.