Black women are more likely than white women to die from even the most treatable types of breast cancer, a study published Tuesday in the Journal of Clinical Oncology found. The findings, experts say, underscore that it’s racial disparities, not biology, driving the biggest differences in death rates between Black and white women. While Black women and white women are diagnosed with breast cancer at similar rates, Black women are 40% more likely to die from the disease. “Within health care there was this notion that an important contributor to disparities was that Black women have higher rates of triple-negative,” which is a particularly aggressive type of breast cancer, said lead author Erica Warner, a cancer epidemiologist at Massachusetts General Hospital. While that does play a role in the higher rates of death, Warner said, “based on these results it isn’t a significant or even a primary reason.”
Warner and her colleagues conducted a meta-analysis that looked at 18 studies with nearly 230,000 patients with breast cancer in total, 34,000 of whom were Black, comparing the mortality rates of Black women and white women with the same breast cancer molecular subtypes. A cancer’s subtype affects how the tumor behaves and responds to treatments, which largely influences mortality rates. For breast cancer, subtypes depend on what type of receptors are found on the surface of the tumor cell. Hormone receptor-positive (HR-positive) tumors have receptors for either estrogen or progesterone, two female hormones. HER2-positive tumors have a kind of receptor that allows the tumor to spread more quickly — or better respond to treatment. In all cases, the receptors can serve as clear targets for treatments. Tumors that have none of these receptors are referred to as triple-negative and are the most difficult to treat. For the most common subtype, HR-positive, HER2-negative, which accounts for 60% to 70% of all breast cancer diagnoses, Black women were 50% more likely to die from the disease than white women. For those with HR-positive, HER2-positive tumors, Black women were 34% more likely to die than white women. Black women were 17% more likely to die from triple-negative breast cancer than white women, a finding that surprised Warner.
