Relationship of clinical and pathologic response to neoadjuvant chemotherapy and outcome of locally advanced breast cancer

Background and Objectives: Neoadjuvant chemotherapy in locally advanced breast cancers produces histologically evaluable changes and frequently reduces the size of the primary tumor. Local clinical response to neoadjuvant chemotherapy may correlate with response of distant metastases. Therefore, clinical or pathological factors, which predict or assess response to treatment, may predict outcome after consideration for initial extent of disease. Methods: To identify pretreatment characteristics of locally advanced breast cancers which predict clinical and pathologic response to neoadjuvant chemotherapy as well as survival and to assess the utility of postoperative histologic changes, we retrospectively studied one hundred forty-four patients with locally advanced breast cancer treated with neoadjuvant chemotherapy between January 1975 and July 1996. Patients were identified through pathology records of the Mount Sinai Medical Center and via one of the author's clinical databases. Pathologic and clinical responses to neoadjuvant chemotherapy were correlated with survival. Stepwise logistic regression was used to identify variables most significantly related to clinical response and pathologic axillary lymph node involvement. Results: Complete clinical response with no palpable tumor was noted in 7/86 patients (8%) and complete pathologic response was achieved in 18/138 patients (13%). Both clinical (P=0.038) and pathologic response (P=0.011) were related to tumor size at the time of diagnosis: smaller tumors were more likely to respond to chemotherapy than larger tumors. Histologic evidence of chemotherapeutic effect, i.e., cytoplasmic vacuolization, change in the number of mitoses and localized fibrosis in lymph nodes did not correlate with clinical or pathologically measured response. Clinical and pathologic response was not associated with age, histology, differentiation, or type of chemotherapy. No residual tumor was found in the axillary nodes of 27% (37) of the patients. Age and complete pathologic response were the only variables significantly related to pathologic nodal status. Eighty-four percent of the 61 patients under 50 years of age had nodal involvement compared to 65% of older patients (P=0.014). Fifty percent of complete pathologic responders had positive axillary lymph nodes compared to 76% of patients who did not have a complete pathologic response (P=0.020). Distant disease-free (P=0.039) and overall survival (P=0.035) were related to the number of involved axillary lymph nodes. After consideration for pathologic lymph node status, no other variable was significantly related to distant disease-free or overall survival in multivariate analysis. No variable was significantly related to local disease-free survival. Age, clinical tumor size, clinical lymph node status, clinical response, type of chemotherapy, histology, differentiation, chemotherapy effects on primary tumor and lymph nodes, decline in the number of mitoses, and degree of fibrosis in nodes were not predictive of distant recurrence or overall survival. Conclusions: This study of patients treated with neoadjuvant chemotherapy for locally advanced breast cancers found little evidence that measurable clinical or pathologic changes attributable to chemotherapy predicted survival. Axillary lymph node status, associated with young age, was the most important prognostic indicator in these patients. (C) 2002 Wiley-Liss, Inc.