BACKGROUNDThe current study was performed to assess whether sequential potentially noncross‐resistant chemotherapy prolongs disease‐free survival (DFS) and overall survival (OS) in patients with operable breast carcinoma.METHODSSeven hundred eighty‐nine patients were registered and followed for a median of 10 years. They were treated in two groups. In Group 1, patients age < 50 years or age > 50 years but with either negative or unknown estrogen receptor (ER) status were randomized to receive 6 cycles of 5‐fluorouracil, doxorubicin, and cyclophosphamide (FAC) alone or followed by 4 cycles of methotrexate and vinblastine (MV). In Group 2, patients age ≥ 50 years with ER‐positive disease were randomized to receive either tamoxifen or combination chemotherapy (FAC + MV) for 10 cycles. Analysis was performed according to allocated treatment (intention to treat), with all randomized patients included.RESULTSIn Group 1 there were no significant differences with regard to DFS or OS between the two treatment arms. The DFS at 5 years was 0.70 and 0.76, respectively, for FAC compared with FAC+MV (P = 0.26). The OS was similar for both groups (0.84 vs. 0.83). It is interesting to note that there was a statistically nonsignificant trend for improved DFS in the FAC + MV arm for patients who were ER‐positive. In Group 2, tamoxifen alone led to more prolonged DFS compared to FAC+MV (0.78 vs. 0.66, respectively) but this did not reach statistical significance (P = 0.28). OS also was associated with a trend (P = 0.86) toward prolonged survival for the tamoxifen arm compared with the FAC+MV arm (0.85 vs. 0.74, respectively).CONCLUSIONSThe results of the current trial concerning sequential adjuvant chemotherapy for operable breast carcinoma, which to our knowledge contains the longest follow‐up presented to date, failed to demonstrate any additional benefit from the addition of 4 cycles of MV to 6 cycles of FAC chemotherapy. Cancer 2003;97:2716–23. © 2003 American Cancer Society.DOI 10.1002/cncr.11396