Sung H, et al. - Researchers assessed the link between terminal duct lobular unit (TDLU) measures and mammographic density (MD) among Chinese breast cancer patients, representing a low-risk population but with high prevalence of dense breasts. This study included 144 breast cancer cases with diagnostic pre-treatment digital mammograms, and were scored using the Breast Imaging Reporting and Data System (BI-RADS) density classification. Three standardized measures (count/100mm², span [μm], and acini count/TDLU) were taken into account to evaluate TDLU features in benign tissues. Dense breasts were reported in 63% of women ≥50 years, with greater TDLU count, longer span, and greater acini count seen in cases with dense breast (BI-RADS, c-d) vs those with non-dense breasts (BI-RADS, a-b). Among women <50 years, 91% had dense breasts, precluding the ability to detect links. The previously reported associations between extensive MD and reduced TDLU involution were further supported, favoring the presumption that breast cancer risk associated with extensive MD may be related to the amount of at-risk epithelium.