Breast density, not oestradiol, drives local platelet activation

The major determinant of local platelet activation is breast density and not oestradiol, a study has found, noting the potential of platelet inactivation as a therapeutic strategy for cancer prevention in postmenopausal women with dense breasts.

“Activated platelets release growth factors that modulate the microenvironment into a protumorigenic state,” the authors said. “Oestrogens may affect the risk of breast cancer and platelet function.”

This study sought to determine whether platelets were activated in situ in breast cancers and in dense breasts tissue of postmenopausal women, as well as explore associations between oestradiol, released platelet factors, and inflammatory proteins. The authors performed sampling of in vivo proteins using microdialysis in 71 women, of whom 10 had breast cancer, 42 were postmenopausal with different breast densities, and 19 were premenopausal.

Increased levels of coagulation factors in dense breast tissue were comparable to those found in breast cancers, which suggested excessive platelet activation. In addition, premenopausal breasts had similar levels of coagulation factors as postmenopausal dense breasts.

Thirteen coagulation factors have been upregulated in dense breasts, of which five showed significant correlations with oestradiol, both locally in the breast and systematically. Furthermore, positive associations were observed between coagulation factors and key inflammatory proteins and matrix metalloproteinases in breast tissue.

“High mammographic density in postmenopausal women is an independent risk factor for breast cancer by undetermined mechanisms. No preventive therapy for this risk group is available,” the authors said.