Predictors of complete pathological response after neoadjuvant systemic therapy for breast cancer.

Background: The aim of the current study was to identify predictors of pathologic complete response (pCR) following neoadjuvant therapy.
Methods: From 2000 to 2007, 518 breast cancer patients received neoadjuvant therapy. Data were compared using chi(2) and Fisher's exact tests and multivariate analysis of variance, as appropriate.
Results: Of 518 breast cancer patients receiving neoadjuvant therapy, 81 (16%) had pCR (77 of 456 [17%] with chemotherapy, 4 of 62 [6%] with endocrine therapy; P < .05). Four factors were associated with pCR: higher tumor grade (P = .015), lack of estrogen receptor (ER) and progesterone receptor (PR) expression (P < .0001), HER2/neu amplification (P = .025), and negative lymph node status (P < .0001). On multivariate analysis, ER and PR negativity, HER2/neu amplification, and negative lymph node status were found to significantly correlate with pCR.
Conclusions: Patients with ER-negative and PR-negative and HER2/neu-amplified breast cancer phenotypes are more likely to experience pCR to neoadjuvant therapy. Although pCR is more frequently observed following neoadjuvant chemotherapy, it is rare following neoadjuvant endocrine therapy.