Feasibility Study of Docetaxel and Cyclophosphamide Six- Cycle Therapy as Adjuvant Chemotherapy for Japanese Human Epidermal Growth Factor Receptor 2-Negative Breast Cancer Patients

Background: We compared treatment completion rates and safety of docetaxel and cyclophosphamide sixcycle therapy (TC6) with docetaxel followed by 5FU, epirubicin and cyclophosphamide (T-FEC) therapy in Japanese patients with human epidermal growth factor receptor 2 (HER2)-negative breast cancer. Materials and Methods: We administered TC6 q3w or T-FEC q3w to HER2-negative breast cancer patients. The primary endpoint of this trial was toxicity. As second endpoints, the treatment completion rate and relative dose intensity were evaluated. Results: The TC6 and T-FEC group consisted of 22 and 21 patients, respectively. Concerning hematological toxicity, grade 3 or higher adverse reactions included neutropenia and febrile neutropenia. As non-hematological adverse events, exanthema and peripheral neuropathy were frequently reported in the TC6 group, whereas more patients of the T-FEC group reported nausea and vomiting. In TC6, the treatment completion rate was 86.4% and the relative dose intensity of docetaxel was 93.2%. In T-FEC, the values were 95.2% and 98.9%, respectively. Conclusions: These results suggest that TC6 is tolerable in Japanese, and that this regimen can also be performed in outpatient clinics. However, with the TC6 regimen, the compliance was slightly lower than with the T-FEC regimen, and supportive therapy needs to be managed appropriately.