Toxicity Assessment of a Phase III Study Evaluating FEC-Doc and FEC-Doc Combined with Gemcitabine as an Adjuvant Treatment for High-Risk Early Breast Cancer: the SUCCESS-A Trial.

This paper aims to evaluate the toxicity profile of additive gemcitabine to adjuvant taxane-based chemotherapy in breast cancer patients. Patients enrolled in this open-label randomized controlled Phase III study were treated with 3 cycles of epirubicin-fluorouracil-cyclophosphamide (FEC) chemotherapy followed by 3 cycles of docetaxel with those receiving 3 cycles of FEC followed by 3 cycles of gemcitabine-docetaxel (FEC-DG). 3690 patients were evaluated according to National Cancer Institute (NCI) toxicity criteria (CTCAE). The study medications were assessed by the occurrence of grade 3-4 adverse events, dose reductions, postponements of treatment cycles and granulocyte colony-stimulating factor (G-CSF) support. No differences in neutropenia or febrile neutropenia were demonstrated. However, thrombocytopenia was significantly increased with FEC-DG treatment (2.0 vs. 0.5 %, p < 0.001), as was leukopenia (64.1 vs. 58.5 %, p < 0.001). With FEC-DG significantly more G-CSF support in cycles 4 to 6 (FEC-DG: 57.8 %, FEC-D: 36.3 %, p < 0.001) was provided. Transaminase elevation was significantly more common with FEC-DG (SGPT: 6.3 %, SGOT: 2 %), whereas neuropathy (1.2 %), arthralgia (1.6 %) and bone pain (2.6 %) were more common using FEC-D. Dose reductions > 20 % (4 vs. 2.4 %) and postponement of treatment cycles (0.9 vs. 0.4 %) were significantly more frequent in the FEC-DG arm. Eight deaths occurred during treatment in the FEC-DG arm and four in the FEC-D arm. The addition of gemcitabine increased hematological toxicity and was associated with more dose reductions and postponements of treatment cycles.