GAINESVILLE, FL—What is the association of mammographic breast density with breast cancer risk by tumor aggressiveness and by menopausal status and current postmenopausal hormone therapy?

That question was addressed in an article in Breast Cancer Research and Treatment. Led by University of Florida-led researchers and including participation from the San Francisco VA Healthcare System, the study included 2,596 invasive breast cancer cases and 4,059 controls selected from participants of four nested case-control studies within four established cohorts: the Mayo Mammography Health Study, the Nurses’ Health Study, Nurses’ Health Study II, and San Francisco Mammography Registry.1

Researchers assessed percent breast density, absolute dense and non-dense areas from digitized film-screen mammograms using a computer-assisted threshold technique and standardized across studies.

Results indicated that, overall, the positive association of PD and borderline inverse association of NDA with breast cancer risk was stronger in aggressive vs. non-aggressive tumors (≥51 vs. 11-25% OR 2.50, 95% CI 1.94-3.22 vs. OR 2.03, 95% CI 1.70-2.43, p-heterogeneity = 0.03; NDA 4th vs. 2nd quartile OR 0.54, 95% CI 0.41-0.70 vs. OR 0.71, 95% CI 0.59-0.85, p-heterogeneity = 0.07).

“However, there were no differences in the association of DA with breast cancer by aggressive status,” researchers wrote, adding, “In the stratified analysis, there was also evidence of a stronger association of PD and NDA with aggressive tumors among postmenopausal women and, in particular, current estrogen+progesterone users (≥51 vs. 11-25% OR 3.24, 95% CI 1.75-6.00 vs. OR 1.93, 95% CI 1.25-2.98, p-heterogeneity = 0.01; NDA 4th vs. 2nd quartile OR 0.43, 95% CI 0.21-0.85 vs. OR 0.56, 95% CI 0.35-0.89, p-heterogeneity = 0.01), even though the interaction was not significant.”

The study team said their findings suggest that associations of mammographic density with breast cancer risk differ by tumor aggressiveness. “While there was no strong evidence that these associations differed by menopausal status or hormone therapy, they did appear more prominent among current estrogen+progesterone users,” the authors explained.

1. Yaghjyan L, Tamimi RM, Bertrand KA, Scott CG, et. Al. Interaction of mammographic breast density with menopausal status and postmenopausal hormone use in relation to the risk of  aggressive breast cancer subtypes. Breast Cancer Res Treat. 2017 Sep;165(2):421-431. doi: 10.1007/s10549-017-4341-2. Epub 2017 Jun 17. PubMed PMID: 28624977; PubMed Central PMCID: PMC5773252.