Pre-treatment hormonal receptor status and Ki67 index predict pathologic complete response to neoadjuvant trastuzumab/taxanes but not disease-free survival in HER2-positive breast cancer patients.

Trastuzumab-containing neoadjuvant chemotherapy achieves a pathologic complete response (pCR) rate of about 40 % in HER2-positive breast cancers, and pCR predicts better survival. A cohort of 102 consecutive Chinese HER2-positive stage II/III patients with neoadjuvant trastuzumab/taxanes were retrospectively analyzed, to evaluate the role of hormonal receptor (HR) status and Ki67 index, along with other parameters, in pCR and survival prediction. pCR rate of the cohort was 44.1 % (45/102). Fifty-three patients were HR-positive and 49 were HR-negative. Median Ki67 index was 40 %, and 49 patients had a high Ki67 index (>40 %) whereas 53 had a low Ki67 index (≤40 %). HR status and Ki67 index were confirmed as the only two parameters associated with pCR in multivariate analysis (hazard ratio = 2.952; 95 % CI, 1.227-7.105; P = 0.016 for HR status and hazard ratio = 2.583, 95 % CI 1.107-6.026, P = 0.028 for Ki67 index). Patients with coexisting HR-negative and high Ki67 index had higher pCR rate (69.2 %), compared to those with either HR-negative alone or high Ki67 alone (hazard ratio = 3.038; 95 % CI, 1.102-8.372; P = 0.029), and to those with coexisting HR-positive and low Ki67 index as well (hazard ratio = 7.071; 95 % CI, 2.150-23.253; P = 0.001). In a median follow-up duration of 25.9 months, 11 disease-free survival events (DFS) were recorded. pCR predicted better DFS (log rank P = 0.018) and was the only significant factor in Cox regression analysis (hazard ratio = 0.184; 95 % CI, 0.038-0.893; P = 0.036). Our study indicates that HR status and Ki67 index are predictors for pCR but not for DFS in HER2-positive patients with neoadjuvant trastuzumab/taxanes, which deserves further investigations.