African-American women tend to start treatment when the cancer is more advanced.

African-American women tend to start treatment when the cancer is more advanced.(JOSE LUIS PELEAZ/GETTY IMAGES)

Even though breast cancer incidence rates are slightly lower overall among African-American women than white women (the incidence is lower still among Hispanic, Asian, and Native American women), a combination of socioeconomic factors and unexplained biological differences make the disease more deadly—and in some cases, harder to treat—in the black community. Also, African-American women under 45 have a greater incidence of breast cancer than white women in the same age range.

Many women are "triple negative"
No one yet knows precisely why, but African-American women are roughly twice as likely as white women to have triple-negative breast cancer—so called because tumor cells in this particularly aggressive form of the disease test negative for estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2). This puts Herceptin and hormone therapies, such as tamoxifen and aromatase inhibitors, entirely out of reach as treatment options. It's suspected that some combination of genetics and environmental factors are at play in triple-negative disease.

Socioeconomic factors
The five-year survival rate for white women is approximately 90%; for African-American women it's roughly 77%. Differences in medical coverage and health-care access likely explain this. Overall, African Americans tend to have more trouble finding consistent, good-quality health care—which amounts to fewer breast cancer screenings and inferior treatment when they are diagnosed.

"Black women have been noted to present [at a doctor's office] with later stage cancer, which has a worse outcome—and they don't always get adequate care," says Ruth ORegan, MD, associate professor of hematology and oncology and director of the translational breast cancer research program at Emory University's Winship Cancer Institute in Atlanta. Seeking medical help when a tumor is larger, higher grade, and/or with more lymph nodes involved can dramatically lower a woman's odds for survival.

Not in the research yet
Another potential problem for African-American women seeking treatment for breast cancer is that they have been underrepresented in chemotherapy breast cancer research, so it has been difficult to determine whether they might metabolize chemotherapy drugs differently from the primarily white research subjects. The issue is being actively researched now.