Response to neoadjuvant chemotherapy in African-American women with triple negative breast cancer

A77 Background: Triple negative tumors (TNT) don9t express the estrogen receptor (ER), progesterone receptor (PR), and epidermal growth factor type 2 (HER2/neu), depriving the oncologist of the usual therapeutic targets. While they account for only about 15% of breast cancers, they represent a higher percentage of breast cancers arising in African-American women who are premenopausal. Although no specific therapy regimen is currently recommended for TNT, neoadjuvant chemotherapy (NC) is commonly used since TNT are often diagnosed at a later stage and are associated with a poorer survival than other breast cancers. Pathologic evaluation of the effect of NC for breast cancer has been useful as an intermediate endpoint, as it correlates with patient survival. Paradoxically, it was observed that TNT respond better to NC, with pathologic complete response (pCR) rates of up to 40% in studies from Europe. The aim of our study was to evaluate the histopathological response of TNT to NC in African-American women and to correlate the response to age and pathologic tumor parameters. Design: African American women with TNT diagnosed from 2003-2007 who had NC were identified. The diagnostic (pre-NC) and excisional (post-NC) slides were reviewed for percent of tumor cellularity, presence of fibrosis, necrosis, macrophages and inflammation. Response to NC was defined as pCR when no residual tumor was histologically identified; and mild, moderate and marked response were defined as reductions of tumor cellularity of 1-30%, 31%-69% and >70% respectively. The response was correlated with age, tumor size, and nodal status. Result: For 26 cases slides were available for review. Tumor size ranged from 1.8 to 12 cm with a median of 3.5 cm and a mean of 4.2 cm. Number of nodes involved by tumor ranged from 0 to 19 with a mean of 4.5. 16 patients were node negative. The age range was 36-73 years. TNT equally distributed in the pre and postmenopausal age. Twenty-five patients received NC in the study. Twelve patients were older than 50 years; of these patients, 2 displayed complete response, 0 displayed marked response, 9 displayed mild to moderate response, and 1 displayed no response. Thirteen patients were younger than 50 years; of these patients, 3 displayed complete response, 5 displayed marked response, 4 displayed mild to moderate response, and 1 displayed no response. Histological appearance in cases of complete response included foamy macrophages, frequently pigment laden and organized in nodule, fibrosis, and lymphocytic response. Cases with partial response variably showed the above features. Non-responders showed larger tumor (19 cm) or multiple node involvement (19/19) while the complete responders had tumors 3 cm or less and 0-1 nodes involvement. NC frequently induced maturation of the basaloid tumors that acquired increased amount of eosinophilic cytoplasm and a "squamoid appearance." Conclusion: In the women studied, cPR correlated with tumor size and nodal status. The rate of pCR was significantly lower in the African American women with TNT included in our study than the pCR reported in European and U.S. studies that included both African-American and Caucasian women, a finding that may be related to the larger size of the primary tumors in our group. Premenopausal women had a statistical significant better chance to show complete or marked response (over 70% tumor cellularity reduction) to NC.