Biological and genetic factors may play as large a role—or larger—as socioeconomic factors do in explaining why black women have lower breast cancer survival rates than white women, or why they suffer from more aggressive forms of the disease, according to new research. One study from researchers at the University of Chicago examined more than 1,200 women with stage I or stage II invasive breast cancer. Though all the women were treated with lumpectomy and radiation, only 78 percent of black women were alive and free of the disease eight years later, as opposed to about 85 percent of white women. Another study from the U.S. National Cancer Institute found genetic differences between breast cancer tumors in black women and in white women.

Researchers hope that these findings will encourage more research addressing why these biological and genetic disparities exist. Meanwhile, the National Cancer Institute is revising its online breast-cancer-risk calculator to account for African-American women’s higher rates. Read more about those revisions here.