A study featured in the August 20 edition in the Journal of the National Cancer Institute reveals that the risk of mortality from breast cancer is not associated with high mammographic breast density in breast cancer patients.

Increased mammographic breast density is one of the strongest risk factors for non-familial breast cancer and even though those with elevated mammographic breast density are at a higher risk of developing breast cancer, so far is remains unclear whether a higher density suggests a lower survival chances in breast cancer patients.

To investigate further, Gretchen L. Gierach, Ph.D., M.P.H., of the Division of Cancer Epidemiology and Genetics (DCEG) at the National Cancer Institute in Maryland and her team analyzed data from the U.S. Breast Cancer Surveillance Consortium, which involved information on 9,232 women diagnosed with primary invasive breast carcinoma between 1996-2005. The average follow-up was 6.6 years. They evaluated the correlation between mammographic breast density and the mortality risk from breast cancer and death of all causes. The measured the mammographic density by Breast Imaging Reporting and Data System (BI-RADS) density classification and observed that density has no impact on the mortality risk once the disease has developed.

The team explains: "It is reassuring that elevated breast density, a prevalent and strong breast cancer risk factor, was not associated with risk of breast cancer death or death from any cause in this large, prospective study."

Although they did discover a link between low density and an elevated risk of breast cancer mortality amongst those that were obese, or patients with large or high-grade tumors, writing:

"One explanation for the increased risks associated with low density among some subgroups is that breasts with a higher percentage of fat may contribute to a tumor microenvironment that facilitates cancer growth and progression."

They conclude that these results support the need of further investigation, saying that, "possible interactions between breast density, other patient characteristics, and subsequent treatment in influencing breast cancer prognosis."

Written by Petra Rattue