Risk factors for neutropenia and febrile neutropenia following prophylactic pegfilgrastim

Aim: Neutropenia is a common side effect of myelosuppressive chemotherapy. Administration of granulocyte colony-stimulating factor is being used for neutropenia prophylaxis, but there are patients who develop neutropenia or febrile neutropenia despite prophylaxis. We attempted to identify potential risk factors for chemotherapy-induced neutropenia in patients with pegfilgrastim prophylaxis. Methods: This was a single-center, retrospective, observational study of patients with breast cancer or diffuse large B-cell lymphoma. We obtained patients’ data from electronic medical records, including baseline demographics and clinical characteristics regarding diseases, treatments and laboratory values. The outcome measures assessed were the incidence of neutropenia and febrile neutropenia. Results: There were a total of 127 patients, including 77 patients with diffuse large B-cell lymphoma (DLBCL) and 50 patients with breast cancer, and we analyzed 722 chemotherapy cycles. We found 88 cases (12.2%) of grade 3 or 4 neutropenia and 39 cases of febrile neutropenia (5.4%). In the univariate analysis, variables associated with both grade 3 or 4 neutropenia and febrile neutropenia were age, cancer type, cancer stage, radiotherapy and platelet count. A multivariate logistic regression model revealed that age, radiotherapy and platelet count were significant factors in severe neutropenia, whereas platelet count was the only statistically significant factor in febrile neutropenia. Platelet counts of less than 150 000/mm³ increased the risk of neutropenia and febrile neutropenia approximately fourfold. In the subgroup analysis of patients with DLBCL, it was found that platelet count was a significant factor for both neutropenia and febrile neutropenia. Conclusion: Among cancer patients with pegfilgrastim prophylaxis, advanced age, absence of radiation therapy and low platelet count were independent predictors of neutropenia, and low platelet count was the predictor of febrile neutropenia.