Incidence of pathologic complete response in women treated with preoperative chemotherapy for locally advanced breast cancer: correlation of histology, hormone receptor status, Her2/Neu, and gross pathologic findings.

Neoadjuvant chemotherapy is the standard of care for patients with locally advanced breast cancer and is used increasingly for large operable breast cancer. The aim of this study was to assess the rate of pathologic complete response (pCR) in our patient population with locally advanced breast cancer and identify predictive factors for pCR after neoadjuvant chemotherapy. We studied a cohort of 205 patients and compared histologic features and biomarkers in the pretreatment biopsy with the corresponding pathologic response in the subsequent resection specimen. A pCR was defined as the absence of any microscopic evidence of tumor in the mastectomy specimen and axillary lymph node dissection. The tumor size was reduced in 60% of patients; 16 patients had a pCR. Histologic grade, histologic type, and hormone status did correlate with a pathologic response. None of the 29 invasive pure micropapillary carcinomas had a pCR. Pathologic complete response among Mexican patients with locally advanced breast cancer is low (8%), and the presence of invasive pure micropapillary carcinoma could be an independent predictor for pCR.