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

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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. Cancer 2005. © 2005 American Cancer Society.