Abstract:ObjectiveTo investigate the impact of low-dose pegylated recombinant human granulocyte colony-stimulating factor (PEG-rhG-CSF) on grade Ⅲ/Ⅳ myelosuppression following chemotherapy. Methods A total of 80 patients with malignant tumors admitted to the First Affiliated Hospital of Anhui University of Science and Technology from April 2022 to September 2023 were selected as research subjects. The patients were randomly divided into the control group (n=40) and the observation group (n=40). The observation group and the control group received subcutaneous injections of 3.0 mg and 6.0 mg PEG-rhG-CSF, respectively, within 24 to 48 hours after chemotherapy. The incidence and duration of grade Ⅲ/Ⅳ neutropenia, febrile neutropenia (FN), adverse reactions, as well as changes in quality of life ［European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30)］ scores before and after treatment were observed in both groups after medication. Results After medication, there was no significant difference in the incidence of grade Ⅲ/Ⅳ neutropenia or FN between the two groups (P＞0.05). The observation group exhibited higher levels for neutrophils compared to control group ［(1.77±0.70)×109/L vs (1.50±0.41)×109/L, t=2.071, P=0.042］. Grade Ⅲ/Ⅳ neutropenia occurred in 1 case in the control group, which lasted for 1 day, while 3 cases occurred in the observation group, which lasted for 2-4 days. Compared with the control group, the occurrence rate of adverse reactions was lower in the observation group (72.50% vs 90.00%, χ²=4.021, P=0.045), and EORTC QLQ-C30 were higher for patients in the observation group (P＜0.05). Conclusion Low-dose PEG-rhG-CSF demonstrates similar efficacy rates as standard doses for prophylactic managing gradeⅢ/Ⅳ myelosuppression following chemotherapy, but it exhibits a lower incidence rate of adverse reactions and improves quality-of-life of patients.