Race modifies the association between breast carcinoma pathologic prognostic indicators and the positive status for HER-2/neu.

ABSTRACT

BACKGROUND: Inferences about the variations in the biology of breast carcinoma between African-Americans and Caucasians have been reported. The difference in the prevalence of positive HER-2/neu breast carcinoma was evaluated and the race-specific risk was assessed for positive HER-2/neu among a cohort of women diagnosed with their first primary breast carcinoma, given the accepted prognostic pathologic indicators for positive HER-2/neu status. METHODS: Demographic, clinical, and pathologic data were collected from existing databases. The status of HER-2/neu was considered positive if the immunohistochemistry score was 3+ or if the fluorescent in situ hybridization indicated a ratio greater than 2. Multivariable logistic regression was used to determine the race-specific risk for HER-2/neu positive breast carcinoma. RESULTS: The difference in the prevalence of HER-2/neu-positive status between African-American and Caucasian women was not statistically significant (P = 0.46). For Caucasian women the likelihood for positive HER-2/neu was statistically significant and increased almost linearly within each stage with nuclear grade dedifferentiation relative to the reference group, women with Stage 1, Grade 1 carcinomas. For African-American women, this risk was not significantly associated with stage, nuclear grade, their interaction term, or other pathologic prognostic indicators. CONCLUSIONS: The findings suggest that race modifies the association between the pathologic prognostic indicators of breast carcinoma and the likelihood of HER-2/neu-positive carcinoma. So far, clinical correlative studies of HER-2/neu have not included race as an independent variable. Concerns about the limited generalizability and the need for validation of the findings across racial lines have been expressed previously.