Black women diagnosed with breast cancer generally have worse outcomes than white women—a difference thought to result in part from Black women’s higher incidence of estrogen receptor (ER)-negative breast cancers, which often do not respond well to therapy. But after analyzing data from eight National Surgical Adjuvant Breast and Bowel Project (NSABP) trials involving more than 9,700 women with localized breast cancer, Maja H. Oktay, M.D., Ph.D., and colleagues Jessica Pastoriza, M.D., and Gina Kim, M.D., found that the disparity was associated with ER-positive breast cancer—and, more specifically, with patients who have residual ER-positive disease following pre-operative chemotherapy.

The researchers concluded that residual ER-positive breast cancer after pre-operative chemotherapy is a risk factor for worse outcomes in Black women but not in white women, perhaps because of biological differences in how the tumor microenvironment responds to chemotherapy. Their paper published online on May 17 in the journal Cancer.

Dr. Oktay is professor of pathology and a co-leader of the Tumor Microenvironment and Metastasis Program of the National Cancer Institute-designated Albert Einstein Cancer Center. She is also an attending physician at Montefiore Medicine. Dr. Pastoriza is an assistant professor of surgery at Einstein and an attending physician at Montefiore Medicine. Dr. Kim is a resident in the department of surgery at Einstein.