Triple negative breast cancer risk 3 times higher among Black women

PHILADELPHIA, Pa. — Triple negative breast cancer is one of the most aggressive and hard-to-treat forms of the disease. It accounts for roughly 10 to 20 percent of all breast cancer diagnoses. Unfortunately, researchers from the University of Pennsylvania report that African-American women are nearly three times more at risk for triple negative breast cancers.

The research team says these findings show the importance of understanding differing breast cancer rates and variations among women of various races and ages. Study authors analyzed data on 200,000 patients who underwent a mammogram between 2006 and 2015 across three different U.S. health systems.

Doctors call this cancer variety “triple negative” because it tests negative for estrogen and progesterone receptors and excess HER2 protein. Consequently, this type of breast cancer doesn’t respond to many treatments which target these three factors.

Among the larger group of 200,000 women, researchers note 29,822 were Black. This is notable because African-Americans are often understudied when it comes to cancer research in general. While this isn’t the first study to conclude Black women are at particular risk for triple negative breast cancer, the extent of these findings is quite notable. Even after adjusting for additional breast cancer risk factors, the findings remained consistent that Black women are significantly more at risk of developing an aggressive form of cancer.

Weight and breast density play major factors

Moreover, researchers also report that doctors are less likely to detect triple negative breast cancers during the standard screening process. Physicians are also more likely to diagnose this form of cancer following a clean (or negative) mammogram screening — an occurrence researchers call interval cancers.

Meanwhile, study authors say there’s a link between greater breast density and an increased risk of all four breast cancer tumor subtypes, with a particularly strong association for premenopausal women and triple negative breast cancer.

An earlier study by the same team discovered that breast density factors in to triple negative breast cancer diagnoses more than any other subtype. Similarly, obesity in general leads to greater triple negative breast cancer risk as well.

“The risk prediction models available are about 60 percent accurate for predicting risk of breast cancer,” says Anne Marie McCarthy, PhD, an assistant professor of epidemiology at Penn, in a university release. “In our studies, we see clear differences in risk factors across these types of breast cancers, and we need to do a better job of identifying how we can accurately predict risk for women, particularly for women of color.”

The study is published in Cancer Medicine.