Ethnic disparities in adjuvant chemotherapy for breast cancer are not caused by excess toxicity in black patients.

Black patients with breast cancer may be at greater risk for chemotherapy-related hematologic toxicity than white patients because of lower baseline blood cell counts. We hypothesize that these baseline differences could lead to excess hematologic toxicity and greater modification of chemotherapy dosing in black patients and that this may contribute to the poorer survival observed in black patients with breast cancer compared with white patients with breast cancer. We performed a retrospective cohort study of black and white patients with breast cancer treated with adjuvant chemotherapy at an academic medical center over an 18-month period. Clinical chart review and pharmacy records were used to collect data on the following: modification of chemotherapy dose or administration; hematologic toxicity; blood cell counts before, during, and after therapy; occurrence of febrile neutropenia; use of prophylactic antibiotics; and use of granulocyte colony-stimulating factor in order to determine whether ethnicity was an independent predictor of these outcomes. Among 23 black patients and 98 white patients with breast cancer treated with adjuvant chemotherapy, modification of chemotherapy administration occurred in 56 patients (46%). Modification was more common among black patients (65.2% vs. 41.8%; relative risk [RR], 1.56; P = 0.04). Black patients were more likely to receive reduced cumulative doses of adjuvant chemotherapy (RR, 2.49; P = 0.03). Our findings suggest that hematologic tolerability of adjuvant chemotherapy is similar in black and white patients. Strategies aimed at improving psychosocial barriers to adjuvant therapy and at reducing surgical complications in black patients may improve overall breast cancer outcomes in this group.