The Color of Cancer

Illustration by Justin Renteria

Scientists have long suspected that a person’s race can affect his or her risk factors for many diseases. And the research continues to support that theory: A 2015 Massachusetts General Hospital study, for example, found profound genomic differences between breast cancers in black and white women. Studying each population as a distinct group could help researchers identify such disparities, providing doctors with more accurate information so they can make better decisions.

Unfortunately, participants in medical studies have historically skewed white. Lynn Rosenberg, a professor of epidemiology at Boston University, explains that up until 20 years ago, researchers recruited from the general hospital population, and didn’t think much about race. “The vast majority of women in those hospitals would have been white women, because the vast majority of the women in the United States are white,” she says. Without making an effort to recruit women of color, Rosenberg says, “you would end up with a study where there weren’t enough women in the minority groups to say anything about them separately.”

As a result, scientists have learned a lot about how diseases express themselves in Caucasians—and far less about how they manifest in people of color. Lacking race-specific data, doctors run the risk of steering their patients wrong. Consider the research on breast cancer. In 2002, the Women’s Health Initiative published a study confirming what many researchers had already suspected: Postmenopausal women taking hormone supplements containing both estrogen and progestin, a regimen called combination therapy, were at an increased risk of some types of breast cancer, by as much as 26 percent. A woman weighing those odds might think that the therapy was worth the risk.

But this past November, research looking exclusively at black women revealed that that population was in fact much more vulnerable than white women to aggressive forms of breast cancer—as much as 50 percent, or nearly double. “This is the first study to really provide some clear-cut, rather definitive evidence on the association among black women,” says Rosenberg, the study’s lead author. “It took a very long time for there to be any awareness that these women weren’t being studied and that they should be studied.”

Scientists like Rosenberg, who also heads BU’s Black Women’s Health Study, are pushing for a different research methodology, one that specifically seeks to learn more about the health of minority populations. “It seemed to us that there was research needed on black women,” she says. “Not just breast cancer, but lots of other conditions.”

Who Should Use Hormone Therapy?

The American Cancer Society has not taken a formal position on whether postmenopausal women should use combination therapy. For her part, Lynn Rosenberg emphasizes that combination therapy should be used only by women who have not had hysterectomies; even for them, she says it should be used sparingly. “It would be a very good idea if women were not using combination therapy,” she says, “or at least not for very long periods of time.”