Breast cancer survival in African-American women by hormone receptor subtypes

Tomi Akinyemiju, Justin Xavier Moore, Sean F. Altekruse

Breast cancer accounts for over 200,000 annual cases among women in the United States, and is the second leading cause of cancer-related deaths. However, few studies have investigated the association between breast cancer subtype and survival among African-American women. We analyzed cancer-related deaths among African-American women using data obtained from the SEER database linked to the 2000 U.S. census data. We examined distribution of baseline socio-demographic and clinical characteristics by breast cancer subtypes and used Cox proportional hazard models to determine associations between breast cancer subtypes and cancer-related mortality, adjusting for age, socio-economic status, stage at diagnosis, and treatment. Among 19,836 female breast cancer cases, 54.4 % were diagnosed with the HER2-/HR+ subtype, with the majority of those cases occurring among women ages 55 and older. However, after adjusting for age, stage, and treatment type (surgery, radiation, or no radiation and/or cancer-directed surgery), TNBC (HR 2.34; 95 % CI 1.95-2.81) and HER2+/HR- (HR 1.39, 95 % CI 1.08-1.79) cases had significantly higher hazards of cancer-related deaths compared with HER2+/HR+ cases. Adjusting for socio-economic status did not significantly alter these associations. African-American women with TNBC were more likely to have a cancer-related death than African-American women with other breast cancer subtypes. This association remained after adjustments for age, stage, treatment, and socio-economic status. Further studies are needed to identify subtype-specific risk and prognostic factors aimed at better informing prevention efforts for all women.