Blog | Friday, September 7, 2012

QD: News Every Day--High mammographic breast density not associated with mortality

Even though women with dense breasts have an increased risk of developing breast cancer, high mammographic breast density was not associated with risk of death from breast cancer or all-cause mortality after accounting for other patient and tumor characteristics, a study found.

Researchers evaluated relationships between mammographic density and risk of death from breast cancer and all causes among 9,232 women diagnosed with primary invasive breast cancer within the U.S. Breast Cancer Surveillance Consortium from 1996 to 2005, with a mean follow-up of 6.6 years.

Results appeared in the Journal of the National Cancer Institute.

1,795 women died, 889 from breast cancer. High breast density (BI-RADS 4) was not related to risk of death from breast cancer (hazard ratio [HR]=0.92, 95% confidence interval [CI]=0.71 to 1.19) or death from all causes (HR=0.83, 95% CI=0.68 to 1.02).

Analyses stratified by stage and other prognostic factors yielded similar results, except for an increased risk of breast cancer death among women with low density (BI-RADS 1) who were either obese (HR=2.02, 95% CI=1.37 to 2.97) or had tumors of at least 2.0 cm (HR=1.55, 95% CI=1.14 to 2.09).

Authors noted that risk factors for the development of breast cancer may not necessarily be the same as factors influencing the risk of death after breast cancer has developed.

For example, the lead author noted in a press release that obesity is inversely related to breast density and could play a role.

"We already know that obesity is a poor prognostic factor for breast cancer in general, but this particular analysis showed that the subgroup of women who were obese and had less-dense, fatty breasts were at greatest risk," the author said. "Our hypothesis is that the fat content in the breast might be enhancing obesity-related mechanisms that heighten tumor aggressiveness in breast cancer. We are conducting studies to better understand the biology of breast density."