Primary objective of the study in patients with a sufficient sonographic response (i.e. iRR = iPR or iCR) to the first 2 cycles of TAC as preoperative treatment of operable (T>/=2cm, N0-2,M0) primary breast cancer: To determine the pCR rate of 6 cycles vs. 8 cycles of docetaxel, doxorubicin and cyclophosphamide (TAC x 6 vs. TAC x 8)