Abstract: Background and purpose: Bone marrow depression is the severest chemotherapy toxicity and neutropenia is a common complication of myelosuppressive chemotherapy. Granulocyte colony-stimulating factor (G-CSF) stimulates the development of hematopoietic progenitor cells to neutrophils and modulates the actions of neutrophils and it can be used for severe neutrophil deficiency after chemotherapy in order to ensure the completion of  the planned chemotherapy regimens. To evaluate the prophylactic effect of rhG-CSF used for chemotherapy-induced myelosuppression in Chinese breast cancer patients. Methods: Breast cancer patients who were taken docetaxel 75 mg/m², epirubicin 65 mg/m² and cyclophosphamide 500 mg/m² (TEC) standard chemotherapy regimen were selected in the retrospective study. Prophylactic group was preventively treated with rhG-CSF between 24-48 h after the first chemotherapy, and control group was not prophylactically treated with rhG-CSF. We would analysis the difference between 2 groups on myelosuppression induced by chemotherapy. Results: Among the 60 cases in prophylactic group, the rate of leukopenia was 25.0% and the rate of neutropenia was 23.3%. While, in the control group of 60 patients, the rates of leucopenia and neutropenia respectively were 78.3% and 73.3%. The difference between the 2 groups was statistically significant (P<0.01). Chemotherapy delayed rates in 2 groups were 5.0% and 25.0% respectively (P=0.002). Delayed time was 2.33±0.58 days and 3.73±0.80 days, respectively (P=0.011), showing significant differences between the 2 groups. The incidence of febrile neutropenia in prophylactic group was 1.7%, and the control group was 20%. The prophylactic group was significantly lower than the control group (P=0.001). rhG-CSF had no effect on the levels of hemoglobin and platelets (P=0.547; P=0.285). The adverse reactions incidence of prophylactic group was 8.3%, while the control group was 21.6%. The difference between the 2 groups was statistically significant (P=0.041). Conclusion: The application of rhG-CSF prophylactically in breast cancer patients after the chemotherapy can reduce the occurring rate of leucopenia, improve the decline of white blood cell and absolute neutrophil count, shorten the duration of chemotherapy-induced bone marrow depression, and reduce the risk of febrile neutropenia. Prophylactic drug use can reduce the adverse reactions of rhG-CSF.

Key words: Recombinant human granulocyte colony-stimulating factor, Myelosuppression, Leucopenia, Prophylactic drug use