TAC Versus TC for Adjuvant Breast Cancer

Both TAC (docetaxel, doxorubicin, and cyclophosphamide) and TC (docetaxel and cyclophosphamide) are established adjuvant chemotherapy regimens for early stage breast cancer. TAC, however, due to the inclusion of the anthracycline doxorubicin, carries a high risk of hematologic and cardiotoxic adverse effects. Substantial evidence supports the concept that early stage HER2-negative breast cancers will benefit similarly from anthracycline-based adjuvant and non-anthracycline-based chemotherapy. Further, approximately 0 to 9% of HER2-negative breast cancers have alterations in the TOP2A gene, which may predict for benefit from anthracycline-based chemotherapy. We hypothesize that 6 cycles of TC versus 6 cycles of TAC will have similar efficacy in the treatment of early stage HER2-negative breast cancer and that TC will have less toxicity. If this hypothesis were upheld and the anthracycline doxorubicin could be eliminated from the regimen while obtaining similar efficacy in this population of patients, it would not only be an important advance in the understanding of the biology of cancer, but it would also be of significant clinical benefit to women with breast cancer.