Figure 3.
Joint associations of histologic epithelium-to-stroma proportion (histologic-ESP) and mammographic breast density (MBD) and risk of subsequent breast cancer development among women with benign breast disease (BBD). Histologic-ESP and percent MBD were dichotomized at their median values among controls (ie, 18.2% and 28.4%, respectively). Unconditional logistic regression models were adjusted for age at menarche, parity and age at first live birth, body mass index, menopausal status and menopausal hormone therapy use, bilateral oophorectomy, history of breast cancer in a first-degree relative, BBD histology, extent of lobular involution, and calendar year of BBD diagnosis, as well as matching factors (age at BBD diagnosis and follow-up time from BBD to cancer). Analyses were performed overall (controls/cases, n = 284/280) and among BBD patients with nonproliferative disease (NPD; controls/cases, n = 204/161) and (C) proliferative disease (PD; with (w)/without(wo) atypia); controls/cases, n = 80/119). Detailed odds ratios and related estimates are presented in Table 4. P values for trend (Ptrend) were assessed by modeling the joint ESP-MBD variable as continuous in the multivariable model. P value for heterogeneity (Phet) was obtained by including a multiplicative interaction term between the joint ESP-MBD variable and BBD histology in the overall, fully adjusted, model. All tests were 2-sided. CI = confidence interval.