Fig. 3
Epithelial nuclear density by stromal area content in the Normal Breast Study (N = 416). a Distribution of epithelial nuclear density by stromal area among pre- and postmenopausal women in the Normal Breast Study. “Mostly fat” denotes tissue samples with <10% stromal area while “adequate stroma” denotes samples with ≥10% stromal area. b Cublic spline curves for epithelial nuclear density by age stratified by stromal area (inflection point at age 55 years). R2 = 0.02, 0.09, and 0.06 for “mostly fat”, “adequate stroma”, and “all” spline curves, reflecting high variability between categories
