Pegylated recombinant human granulocyte colony-stimulating factor (PEG-rhG-CSF) is rhG-CSF chemically modified by a single methoxy polyethylene glycol group; it is able to alleviate neutropenia with a single dose (1,2) However, due to the short time that it has been used in China, oncologists have many questions about the use, dosage and safety of this therapy in the treatment of patients with grade IV neutropenia. This evidence concerns the gene CSF3 and Decreased total neutrophil count.