An abbreviation for a chemotherapy combination used to treat breast cancer.  It includes the drugs doxorubicin hydrochloride (Adriamycin) and cyclophosphamide, followed by treatment with paclitaxel (Taxol) and trastuzumab (Herceptin).  Also called AC-T-T, AC-T-T regimen, and sequential AC/Taxol-trastuzumab regimen.