Docetaxel and cyclophosphamide as neoadjuvant chemotherapy in HER2-negative primary breast cancer

Docetaxel plus cyclophosphamide (TC) has recently been established as a standard adjuvant chemotherapy regimen for HER2-negative (HER2-) operable breast cancer. However, the efficacy and tolerability of TC as neoadjuvant chemotherapy (NAC) remain unclear. We, therefore, conducted a prospective study to evaluate the efficacy of TC NAC in HER2- primary breast cancer.

Patients who were diagnosed with HER2-, N0-N1, invasive breast cancer between July 2011 and February 2014 and had tumors measuring 1-7 cm were eligible. The subtypes were classified using a core-needle or vacuum-assisted breast biopsy. The efficacy and safety of NAC comprising TC (75 mg/m² docetaxel and 600 mg/m² cyclophosphamide, four cycles every 3 weeks) were investigated in a prospective study in patients with HER2- breast cancer.

Fifty-two patients were enrolled. Of these, 94.2 % (49/52) completed four cycles of TC. The overall pCR rate was 16.3 % (8/49). The pCR rates for patients with luminal A-like breast cancer [estrogen receptor-positive (ER+), Ki67 index of <20 %, and HER2-], luminal B-like breast cancer (ER+, Ki67 index of >20 %, and HER2-), and triple-negative breast cancer [ER-negative (ER-) and HER2-] were 0 % (0/12), 4.3 % (1/23), and 50.0 % (7/14), respectively. Almost all pCRs occurred in triple-negative breast cancer patients.

The pCR rate of TC NAC was not very high despite the high completion rate. TC NAC was effective against the triple-negative subtype, resulting in a higher pCR rate. Therefore, our results indicated that TC NAC showed limited efficacy in luminal subtype breast cancer with the exception of the triple-negative subtype.