Why dense breast tissue raises cancer risk

This article was originally on a blog post platform and may be missing photos, graphics or links. See About archive blog posts.

Having dense breasts has been linked to a higher risk of breast cancer. One reason may be because it’s harder to find tumors on the mammograms of women with dense breasts. Dense breast tissue shows up white on a mammogram, as do tumors, making it harder to see them and perhaps delaying diagnosis. But research presented at the San Antonio Breast Cancer Symposium shows that dense breast tissue contains more cells believed to produce breast cancer compared with non-dense tissue.

A second study (both studies are from scientists at Mayo Clinic) found that dense breast tissue has more aromatase enzyme than non-dense tissue. Aromatase helps convert androgen into estrogen. A higher level of estrogen is related to a higher cancer risk.

The studies are the first to examine both dense and non-dense tissues taken from healthy volunteers. The 60 volunteers, ages 40 to 85, submitted to eight core-needle biopsies. None of the women had a history of breast cancer. The study showed that dense tissue contains more epithelium tissue (milk glands and duct cells) and stroma tissue (which is connective tissue) and much less fat compared with non-dense tissue.

‘No one knows why density increases breast cancer risk, but we are attempting to connect the dots,’ Celine Vachon, the lead author of one of the studies, said in a news release.

The study abstracts can be found at the website of the San Antonio Breast Cancer Symposium.

-- Shari Roan