Abstract: Background and purpose: Myelosuppression is the most common dose-limiting toxicity of tumor chemotherapy in which leukocytopenia and neutropenia are the most common conditions. Not only are uptitrations of the doses of chemotherapeutic drugs limited, but also normal process of the chemotherapy is affected. Filgrastim-Recombinant Human Granulocyte Colony-Stimulating Factor (rhG-CSF) has the activity of stimulating the formation of granulocyte colony and promoting the growth, proliferation and differentiation of granulocytes which can be significantly effective on leukocytopenia and neutropenia induced by chemotherapy. In this study, we observed the leukogenic effects, toxic and side effects of low, medium, and high doses of rhG-CSF used prophylactically after chemotherapy in patients with advanced non-small cell lung cancer (NSCLC), to explore a rational application strategy for rhG-CSF.. Methods: One hundred and twenty six patients with pathologically proved advanced non-small cell lung cancer (NSCLC) under chemotherapy were digitally randomized to A, B and C groups. Filgrastim was given to patients of the three groups 24h after the end of chemotherapy. The dosages are: Group A (low dose): 300 μg of Filgrastim, s.c., qd × 1 day; Group B (medium dose): 300 μg of Filgrastim, s.c., qd × 2 days; Group C (high dose): 300 μg of Filgrastim, s.c., qd × 3 days. Then the signs and symptoms as well as toxic and side effects of Filgrastim after medication were observed. Results: Prophylactic usage of medium and high dosages of rhG-CSF could maintain WBC count at no less than 4.0×10⁹/L in nearly 60% of patients. In patients with Grade III leukopenia, more days were needed for recovery of white blood cell (WBC) count with the low dose, while significantly (P<0.05) less days were needed with the high dose. In view of the dynamic changes of neutrophil(ANC), additioning of the high dose of rhG-CSF after chemotherapy could increase the average level of ANC, notably shortening the duration of low ANC caused by chemotherapy. The incidence of infections was 4.76% for the 126 patients as a whole, 9.52% for the low dose group, and 4.76% for the middle dose group. The patients could tolerate the slight side effects incurred during treatment with Filgrastim. Conclusion: All of the three doses (low, medium, and high) of prophylactic administration of Filgrastim after chemotherapy can promote recoveries of WBCs and neutrophil granulocytes and reduce opportunities of infections. High doses of rhG-CSF can be faster and safer in increasing WBCs and neutrophil granulocytes.

Key words: Recombinant human granulocyte-colony stimulating factor, Neutropenia, Tumor, Chemotherapy