Five-year disease-free survival and overall survival rates were “indistinguishable” in patients with operable, node-positive, HER2-nonamplified breast cancer treated with the sequential or combination regimens of doxorubicin/cyclophosphamide (AC) and docetaxel (T). The Breast Cancer International Research Group (BCIRG) 005 Trial compared four cycles of doxorubicin with cyclophosphamide, followed by docetaxel (AC > T) with six cycles of the triple combination TAC. Following completion of chemotherapy, radiation was administered as indicated and patients with hormone receptor–positive disease received adjuvant hormonal therapy with tamoxifen and/or aromatase inhibitors.
BCIRG 005 involved 335 centers in 37 countries and enrolled 3,298 patients, equally divided between the two study arms and with well-balanced characteristics. The median age of the patients was 50. Nearly 60% had a primary tumor greater than 2 cm and nearly 40% had four or more lymph nodes involved. As reported in the Journal of Clinical Oncology, the 5-year disease-free survival rates were 78.6% in the AC > T group and 78.9% in the TAC group. The 5-year overall survival rates were 88.9% in the AC > T group and 88.1% in the TAC group.
“When put into the context of reported adjuvant chemotherapy studies, it becomes evident that both TAC for six cycles and AC for four cycles followed by docetaxel for four cycles are among the most active regimens currently available for the adjuvant treatment of early, HER2-nonamplified breast cancer,” the investigators stated.
“The toxicity of both regimens was manageable,” the authors reported. While the incidence of neutropenic infection was similar in both groups, other aspects of the toxicity profiles were different. “TAC was associated with more febrile neutropenia and thrombocytopenia, and AC > T was associated with more sensory neuropathy, nail changes, and myalgia,” the investigators noted. Because the two regimens “have equivalent efficacy, the choice of regimen requires balancing the differences in toxicity and treatment duration,” they concluded.