Background: 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.
Method: 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.
Results: 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).
Conclusions: 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.