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Chicago, IL—Adjuvant FAC (5-fluorouracil, doxorubicin, and cyclophosphamide) followed by weekly paclitaxel was associated with a slight but significant improvement in disease-free survival (DFS) vs FAC alone in patients with high-risk, node-negative breast cancer at a median follow-up of more than 5 years, according to results of the first efficacy analysis1 presented here at the 2012 annual meeting of American Society of Clinical Oncology.
In the phase 3 randomized GEICAM/2003-02 trial,1,2 the proportion of patients who were disease-free after a median follow-up of 63.3 months was 93% among patients in the FAC followed by weekly paclitaxel arm and 90% among those in the FAC arm (log-rank P-value=0.0432), for a 27% reduction in risk of DFS events (HR 0.733 [95% CI 0.542–0.992]; P=0.0441), reported lead author, Miguel Martín, MD, PhD, of the Spanish Breast Cancer Research Group and Hospital General Universitario Gregorio Marañón, in Madrid, Spain. These results were due to fewer breast cancer relapses in the FAC followed by weekly paclitaxel arm and more deaths in the FAC arm.
Of the 100 patients who developed tumor relapse in the FAC group, 68 had breast cancer, 21 had a second primary malignancy, and 11 died; in the FAC followed by weekly paclitaxel group, 50 had breast cancer, 21 had a second primary malignancy, and 2 died. Early OS results—at 41 deaths in the FAC arm and 31 in the FAC followed by paclitaxel arm—showed a hazard ratio of 0.766 (95% CI: 0.481–1.222).
Previously, adjuvant trials3,4 have shown sequential weekly addition of paclitaxel to anthracyclines improves outcome in patients with operable node-positive breast cancer. The presented trial enrolled patients with node-negative at the time of diagnosis, Dr. Martín noted in an explanation of the study’s rationale.
In the late 1970s and early 1980s, use of anthracycline-containing combinations such as FAC and FEC (5-fluorouracil, epirubicin, and cyclophosphamide) for the treatment of early breast cancer were shown to be associated with reductions in risk for recurrence of 11.2% (P<0.0001) and in risk for death of 16% (P<0.00001) compared with CMF (cyclophosphamide, methotrexate, and 5-fluorouracil).5,6
Subsequently, the Eastern Oncology Group E1199 trial conducted by the North American Breast Cancer Group (ECOG,SWOG, CALGB, nCCTG) found provocative differences in efficacy between paclitaxel vs docetaxel or the weekly vs every 3 weeks schedule, suggesting that weekly paclitaxel was the preferred regimen. The four-arm study concluded that significantly better DFS was observed in the group that received weekly paclitaxel and in the group that received docetaxel every 3 weeks vs paclitaxel every 3 weeks, considered the standard.3