Correlation between HER-2 expression and response to neoadjuvant chemotherapy with 5-fluorouracil, doxorubicin, and cyclophosphamide in patients with breast carcinoma

BACKGROUND. The objective of this study was to determine whether HER-2 overexpression is associated with improved response to neoadjuvant chemotherapy with 5-fluorouracil, doxorubicin, cyclophosphamide (FAC) in patients with breast carcinoma. METHODS. Ninety-seven patients with Stage I-III breast carcinoma were included. HER-2 expression was determined by routine clinical laboratory assessment, and tumors with 3 + immunohistochemistry staining intensity or gene amplification by fluorescent in situ hybridization were considered HER-2 positive. Response was assessed by physical examination, imaging assessment, and pathologic assessment at the time of surgery. RESULTS. The median patient age was 45 years. At baseline, 68% of patients had lymph node positive disease, 87% had ≥ T2 tumors, and 28% of patients had HER-2 positive tumors. Eighty-four percent of patients received four courses of FAC, 8% of patients received 3 courses of FAC, and the remaining 8% of patients received 5-6 courses of FAC. The clinical response rate (complete response [CR] and partial response [PR]) was 78%, the imaging response rate (CR and PR) was 64%, and 15% of patients had a good pathologic response, defined as a CR or minimal residual disease (tumor measuring < 1 cm in greatest dimension and negative lymph nodes). Concordance between the three methods of response assessment (clinical, pathologic, and imaging) was modest and was best between clinical assessment and imaging assessment (64% concordance). HER-2 status did not correlate with pathologic or clinical response (assessed by physical examination or imaging), although a nonsignificant trend was noted toward better response in patients with breast tumors that overexpressed HER-2. CONCLUSIONS. The authors found no significant correlation between HER-2 expression and clinical or pathologic response to neoadjuvant chemotherapy in patients with breast carcinoma.