Comparison of the efficacy and safety of the EC-T (epirubicin/cyclophosphamide followed by docetaxel) and TCb (docetaxel/carboplatin) neoadjuvant regimens in early TOP2A-normal stage II-III breast cancer.

This study aimed to compare the efficacy and safety of the EC-T (4 cycles of epirubicin 90 mg/m2 + cyclophosphamide 600 mg/m2, followed by 4 cycles of docetaxel 75 mg/m2) and TCb (6 cycles of docetaxel 75 mg/m2, intravenous drip (ID), day 1 + carboplatin AUC 6, ID, day 1) neoadjuvant regimens in patients with TOP2A-normal stage II-III breast cancer. This study analyzed 280 patients enrolled from three studies registered with ClinicalTrials.gov (NCT03140553, NCT03154749, NCT03507465) with early TOP2A-normal stage II-III breast cancer who received neoadjuvant chemotherapy, including 100 patients who received the EC-T regimen and 180 patients who received the TCb regimen. The primary endpoint was the ratio of RCB 0/1 (residual cancer burden 0/1) after neoadjuvant chemotherapy. The secondary endpoint was the safety of the two groups. There was no significant difference in the ratio of RCB 0/1 between the two groups (23% vs. 23.9%, p=0.614). Among the triple-negative breast cancer patients, the efficacy did not differ between the two groups (40% vs. 32%, p=0.52). Among the lymph node metastasis patients, the efficacy of the EC-T group was significantly better than that of the TCb group (14% vs. 2.6%, p=0.03). Regarding the side effects, the incidence of grade 3/4 anemia was higher in the EC-T group than in the TCb group (21.0% vs. 8.33%, p=0.002), while the incidence of grade 3/4 neutropenia was higher in the EC-T group than in the TCb group (17% vs. 14.44%, p=0.570), and the incidence of grade 3/4 thrombocytopenia was low in each group (EC-T group: 6 % and TCb group: 7.22%, p=0.697). In the EC-T group, grade 3/4 nausea and vomiting occurred in 5 patients. The EC-T group showed a higher rate of grade 3/4 myalgia than the TCb group (7% and 4.44%, respectively, p=0.363). To conclude, the TCb regimen can be used as an alternative regimen for TOP2A-normal stage II-III breast cancer patients in neoadjuvant chemotherapy. However, in patients with node-positive tumors, EC-T is still recommended. Though no difference of grade 3/4 thrombocytopenia in two groups, grade 4 thrombocytopenia caused by the carboplatin-containing regimen should be taken seriously.