Prophylactic Pegfilgrastim Versus On-Demand Filgrastim During Docetaxel and Cyclophosphamide Chemotherapy in...

In patients with early-stage breast cancer, myelosuppressive chemotherapy, such as docetaxel and cyclophosphamide (TC) chemotherapy, is frequently introduced as an adjuvant treatment postoperatively. This regimen commonly causes febrile neutropenia (FN); therefore, the use of pegfilgrastim, a newly developed granulocyte colony-stimulating factor (G-CSF), plays an important role in preventing the occurrence of FN. We evaluated the clinical advantage of pegfilgrastim during TC chemotherapy by comparing it with conventional filgrastim.

Overall, 85 patients with stage I or II breast cancer who received TC chemotherapy were retrospectively analyzed by collecting data from the patient charts. The enrolled patients were divided into two groups: patients who received prophylactic pegfilgrastim administration, 36 (42.4%) (PEG(+)), and those who received chemotherapy only with the contemporary G-CSF agent, filgrastim, which was administered when they suffered from FN or severe neutropenia, 49 (57.6%) (PEG(-)). We evaluated the effectiveness of the use of pegfilgrastim for the prevention of FN, maintaining a high relative dose intensity (RDI) (first endpoint), and explored the effect of the use of pegfilgrastim on disease-free survival (second endpoint). For statistical analyses, Fisher's exact test was applied mainly to categorical variables. The ratios of adverse event frequency in the PEG(-) and PEG(+) groups were calculated and compared. The Mann-Whitney U test was employed for the RDI of docetaxel and cyclophosphamide. The DFS rate of the PEG(-) and PEG(+) groups was estimated using the Kaplan-Meier method and compared using the log-rank test.

The number of patients diagnosed as Grade 3 to 4 "neutrophil count decrease" according to the Common Terminology Criteria for Adverse Events version 5.0 was 21 (42.8%) and six (16.7%) in the PEG(-) and PEG(+) groups, respectively (P = 0.0238). The odds ratio for the onset of Grade 3 to 4 "neutrophil count decrease" in the PEG(+) group compared to that in the PEG(-) group was 0.1143 (95% confidence interval, 0.0175-0.7446). The difference in disease-free survival rates could not reach a significant level because the number of events was small.

The administration of pegfilgrastim significantly reduced the risk of FN development, with acceptable adverse events. The chemotherapy RDI of patients who received prophylactic pegfilgrastim was significantly higher than that of those who were administered conventional filgrastim at the physician's discretion. In the present study, we verified the clinical efficacy of pegfilgrastim in patients receiving TC chemotherapy. The prophylactic use of pegfilgrastim is considered to be essential for carrying TC chemotherapy safely.