Impact of colony-stimulating factors to reduce febrile neutropenic events in breast cancer patients receiving docetaxel plus cyclophosphamide chemotherapy

Abstract

Data from US Oncology Adjuvant Trial 9735 has shown that four cycles of docetaxel plus cyclophosphamide (TC) improved disease-free and overall survival when compared against doxorubicin and cyclophosphamide (AC) in early-stage breast cancer. The febrile neutropenia (FN) rate was 4% in this study without primary granulocyte colony-stimulating factors (G-CSF) prophylaxis. However, the incidence of docetaxel-induced myelosuppression is recognized to be higher among Asian population. Hence, this study was designed to evaluate the impact of G-CSF to reduce FN-related events in Asian cancer patients treated with TC. This retrospective cohort study was conducted on Asian breast cancer patients who have received intravenous docetaxel 75 mg/m(2) and cyclophosphamide 600 mg/m(2) between 2006 to 2008. Patients did not receive oral antibiotic prophylaxis, and prophylactic G-CSF after chemotherapy was prescribed under the discretion of the primary oncologist. During cycle 1 of chemotherapy, 6.3% patients received G-CSF manifested FN, while 25% patients who did not receive G-CSF manifested FN (RR = 0.252, 95% CI 0.102 to 0.622). Introduction of G-CSF as primary prophylaxis provided an absolute risk reduction of FN events by 18.7%. Chemotherapy doses were maintained throughout all cycles. Patients with pretreatment white blood cell counts (WBC) below 6.0 × 10(3)/mm(3) and absolute neutrophil counts (ANC) below 3.1 × 10(3)/mm(3) were associated with higher rates of FN during Cycle 1 (p = 0.009, p = 0.007). Our findings indicate that TC was associated with higher rates of FN than reported in the clinical trial. The 25% incidence fulfills the requirement of primary prophylaxis with G-CSF. Routine administration of G-CSF is highly recommended to reduce the rates of FN in breast cancer patients receiving TC.