Disparate racial benefits of chemotherapy in breast cancer.

Abstract #2091 Purpose: Patients with triple negative breast tumors (TNTs) have high recurrence and poor survival rates. African-American (AA) women have a higher prevalence of TNTs and worse outcomes than Caucasian (CA) women. The addition of a taxane to anthracycline-based chemotherapy in the adjuvant setting appears to improve outcome to a greater extent in estrogen receptor (ER)- compared to ER+ cancers. There is insufficient data examining currently approved adjuvant chemotherapy regimens in AA. We evaluated the outcomes associated with different chemotherapy regimens in a largely AA group with early stage breast cancer. Methods: The Surveillance Epidemiology End Results (SEER) registry identified 509 AA or CA female breast cancer patients (Stages I-III) diagnosed during 2003-2004 at 3 Atlanta-based hospitals who were residents of Fulton/DeKalb counties. SEER data was augmented by medical record abstraction. Frequency distributions, chi-square tests of independence, logistic regression, and Cox models were used to assess recurrence and mortality by tumor subtype and chemotherapy regimen. Results: The mean follow-up was 3.2 years. Of 509 patients, 66.2% were AA. TNTs represented 17.1% (N=87), with a higher proportion in AA (20.2%) than CA (11.0%) women. Compared to ER+PR+HER2- tumors, patients with TNTs were more likely to experience a recurrence (HR=3.1, 95% CI 1.3, 7.0) and to die (HR=2.9, 95% CI 1.3, 6.3) after adjusting for receipt of chemotherapy, age, race, socioeconomic status, stage, and grade. Among chemotherapy-treated women with ER+PR+HER2- cancers, AA had higher recurrence (27.1% v. 8.3%) and death (21.3% v. 3.7%) rates than CA women; however, similar recurrence (42.2% v. 33.3%) and death (28.0% v. 35.7%) rates were found in the chemotherapy-treated AA and CA patients with TNTs. Among women treated with adriamycin-based regimens, the addition of a taxane did not appear to impact recurrence or survival in the ER+PR+HER2- or TNT subgroups. Conclusions: This data supports prior data demonstrating a two-fold increase in TNTs in AA compared to CA women. TNTs in this majority AA population were associated with a higher likelihood of short-term recurrence and mortality than other subtypes. Chemotherapy was not as beneficial for AA women with ER+PR+HER2- tumors compared to CA women. No statistically significant differences in outcome were noted for AA or CA women with TNT treated with chemotherapy. The addition of a taxane to adriamycin-based chemotherapy did not improve recurrence or survival rates for women with ER+PR+HER2- or TNTs. Clinical trials with consideration of racial diversity are needed to further assess the effectiveness of chemotherapy regimens on reducing recurrence and mortality in breast cancer patients. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2091.