Purpose: Breast cancers are often classified on the presence/absence of hormone receptors, and growth factor oncogenes (estrogen receptor, progesterone receptor, HER2). Triple-negative breast cancers, negative for these markers, do not benefit from targeted therapy. We compared clinicopathologic parameters and immunohistochemical markers of prognostic and/or predictive significance, and outcome between African American and Caucasian triple-negative breast cancer patients.
Methods: Invasive triple-negative breast cancers from African American (n=94) and Caucasian (n=68) patients were studied. Clinicopathologic features (age, tumor size, grade, lymph node status, angiolymphatic invasion, visceral metastases) and survival (overall and progression free) were compared. Marker expression (CK5, CK7, CK8, CK14, CK18, CK19, vimentin, CD44, c-Kit, epidermal growth factor receptor, p-cadherin, p53, p63, topoisomerase II, androgen receptor, Ki-67) was assessed in tissue microarrays.
Results: Significant differences between African American and Caucasian women were observed for mean age and tumor size. African Americans had a trend toward greater lymph node involvement than Caucasians. The following markers were found in significantly different frequencies between the 2 groups: CK5, CK8, CK19, c-Kit, androgen receptor, and high Ki-67. African Americans show shorter overall and progression-free survival. Other clinicopathologic parameters, markers, and outcome were present at similar frequencies.
Discussion: African American triple-negative breast cancers were more aggressive, occurring at a younger age, being larger, with higher proliferation, patients more frequently dying of disease, and with a trend toward positive lymph node status. Heterogeneity of marker expression suggests variation in the genetics of breast carcinomas in different races.