The SUCCESS-C trial: Interim analysis of toxicity evaluating the role of an anthracycline-free chemotherapy regimen in the adjuvant treatment of HER2/neu-negative breast cancer.

Abstract

1070 Background: Taxane-based anthracycline containing chemotherapy has been established as treatment option in the adjuvant setting of early breast cancer. Indication was recently enlarged for high risk node negative breast cancer. Promising retrospective data indicate equi-efficacy of anthracycline-free chemotherapy in Her2/neu-negative patients (Gennari et al., Slamon et al.). Anthracycline-free regimens are probably associated with less long-term toxicities, especially cardiac toxicities. Methods: The SUCCESS-C trial is an open-label, multicenter, 2x2 factorial design, randomized controlled, phase III study comparing the disease free survival in patients treated with 3 cycles fluorouracil 500mg/m2-epirubicine 100mg/m2-cyclophosphamide 500mg/m2 (FEC) chemotherapy, followed by 3 cycles docetaxel 100mg/m2 (D) chemotherapy, versus 6 cycles docetaxel 75mg/m2-cyclophosphamide 600mg/m2 (DC) chemotherapy. Monitored toxicity data after end of treatment are available from 1,452 patients. Results: Chemotherapy was prematurely stopped in 51 pts (7.2%) receiving FEC-D and in 57 pts (7.7%) with DC (p=0.71). Dose reductions occurred significantly more often in the FEC-D arm (2.7%) than in the DC arm (1.9%, p=0.024), reasons did not differ significantly between both arms (p=0.093). Incidence of treatment-postponement was significantly higher for FEC-D (9.4% FEC-D vs. 7.6% DC; p=0.0008). Haematological toxicity as a reason for treatment-postponement occurred significantly more frequent within the FEC-D-arm (FEC-D: 18.1%, DC: 6.6%, p<0,0001); non-haematological toxicity as a reason for treatment postponement was nearly equal within both arms (8.6% FEC-D vs. 8.8% DC, p=0.9). G-CSF support was applied in 22.7% of all chemotherapy cycles (FEC-D: 22.2% vs. DC: 23.2%, p=0.21). Severe toxicities (NCI-grade > 2) were reported in 910 cases for FEC-D and in 848 cases for DC arm (p= 0.02). Conclusions: Significantly more dose-reductions of chemotherapy and a significant higher incidence of treatment-postponement occurred in the FEC-D arm. The toxicity profiles of both treatment arms differ discretely and support the continuation of the trial until target recruitment (n=3,547).