Response and Prognosis of Docetaxel and Cyclophosphamide as Neoadjuvant Chemotherapy in ER+ HER2- Breast Cancer: A Prospective Phase II Study

Our prospective phase II study showed that a docetaxel and cyclophosphamide regimen as neoadjuvant chemotherapy achieved a high clinical response rate in patients with stage II to III estrogen receptor-positive human epidermal growth factor receptor 2-negative breast cancer. A docetaxel and cyclophosphomide regimen without anthracycline as neoadjuvant chemotherapy might be an option for patients with estrogen receptor-positive human epidermal growth factor receptor 2-negative breast cancer without high-risk factors. Background: Although a docetaxel and cyclophosphomide (TC) regimen without anthracycline as adjuvant therapy became one of the standard regimens especially for ER-positive (ER-)/human epidermal growth factor receptor 2-negative (HER2(-)) primary breast cancer, the efficacy of TC as neoadjuvant chemotherapy (NAC) is not known. We conducted the prospective trial to assess the efficacy of a TC regimen in the neoadjuvant setting for stage II to III ER+/HER2 primary breast cancer. Patients and Methods: A TC regimen that included 75 mg/m(2) of docetaxel and 600 mg/m(2) of cyclophosphamide for 4 cycles every 3 weeks was administered as NAC. Primary endpoints are the rate of clinical response (clinical partial response and clinical complete response) and pathologic complete response; secondary endpoints are the disease-free survival and overall survival rates. Results: Thirty (71.4%) of 42 tumors had clinical response. No patient achieved pathologic complete response. At the median follow-up period of 105.2 months (range, 12.1-119.7 months), the disease-free survival rate was 81.6%, and the distant disease-free survival rate was 86.8%. In terms of survival, only 1 patient died during the study period. The overall survival rate was 97.4% during the study period. Patients who developed distant recurrence had a trend to have progesterone receptor-negative or weakly positive compared with those who did not develop any recurrence (85.7% vs. 45.2%; P =.05). Conclusions: Our prospective study showed that a TC regimen as NAC achieved a high clinical response rate in stage II to Ill ER+/HER2(-) breast cancer. A TC regimen without anthracycline as NAC might be one of the options for patients with ER+/HER2(-) breast cancer without high-risk factors including progesterone receptor negativity. (C) 2020 Elsevier Inc. All rights reserved.