Abstract P5-12-01: A comparison of hormone receptor status in black women born in the U.S., West Africa, East Africa and the Caribbean - A SEER analysis

Abstract

Abstract Background: Breast cancer is the leading cancer diagnosed among women in the United States (U.S.) and is second only to lung for cancer-related deaths in women. Although white women have a higher incidence of breast cancer, African American (AA) women with breast cancer have higher breast cancer related mortality and have a lower five year survival (73.8%) compared to their white counterparts (81.6%). AA women are also diagnosed at a younger age, with 30-40% of AA women diagnosed under 50, compared to 20% of whites, and are more likely to present with more estrogen receptor negative/progesterone receptor negative (ER-/PR-) tumors than whites (42% vs. 29% respectively). Other studies suggest these disparities extend to black African women and white European women. The aim of this study is to determine whether breast cancer characteristics seen in U.S. born black women are comparable to African born black women and to provide additional insight on the role of race and genetic ancestry in breast cancer. Methods: Surveillance, Epidemiology, and End Results (SEER) data (SEER 18 Registries) was used to examine hormone receptor (HR) status among 30,003 black women, born in the U.S. (28,838), West Africa (167), East Africa (183), or the Caribbean (815), diagnosed with a first primary breast cancer from 2000 through 2009. Chi-square tests were used to determine whether clinical variables differed by ethnic group. Proportional incidence ratios (PIR) and 95% confidences intervals (CI) were calculated to estimate excess risk of ER-/PR- tumors between the populations. Results: There were no statistically significant differences in axillary lymph node, stage, histologic type, or surgical treatment at presentation by ethnic group. There was no statistically significant difference in the proportion of ER-/PR- receptor status comparing US blacks to black women born in West Africa (p-value = 0.16, PIR = 0.77, 95% CI: 0.56-1.05), however women from East Africa and the Caribbean were less likely to have ER-/PR- breast cancers compared with US born blacks. (PIR = 0.52, 95% CI: 0.35-0.74, p < 0.0001 PIR = 0.84, 95% CI: 0.73-0.97, p< 0.01 respectively). The crude overall 5-year survival rate of West African, East African and Caribbean born black women was significantly higher than those born in the U.S. (75.7%, p = 0.023, 85.9% p <0.0001, 84.0% p<0.0001, 65.3% respectively). Discussion: Our results agree with historical data showing that many AA women have ancestral origins in West Africa and provides additional evidence supporting the role of ancestral genetics in breast cancer susceptability. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-12-01.