Predictors of Chemotherapy Induced Neutropenia in Patients with Breast Cancer

Objective: Chemotherapy induced neutropenia (CIN) is a common adverse effect of chemotherapy and interferes with optimal dosing. The purpose of this study was to determine the frequency and risk factors of grade 3/4 CIN (absolute neutrophil count <1000/mm ³) in breast cancer patients receiving systemic chemotherapy. Material and Methods: This single center retrospective study comprised 679 female patients with breast cancer who were treated with anthracycline and/or taxane based or cyclophosphamide, methotrexate and 5-fluorouracil (CMF) chemotherapy regimens. Patients who received primary prophylaxis with granulocyte-colony stimulating factor were excluded. Demographic and clinical risk factors for grade 3/4 CIN were evaluated with multivariate regression analysis. Results: The frequency of grade 3/4 CIN was 25.3% and mostly occurred during the first 4 cycles of chemotherapy. In multivariate analysis, stage 4 disease [odds ratio (OR): 3.1], having 2 or more comorbidities (OR: 2.5), and low baseline white blood cell count (<4000/mm ³vs. >10000/mm ³, OR: 7.84) were associated with increased risk for grade 3/4 CIN. Being overweight or obese was found to be protective for the occurrence of grade 3/4 CIN (OR: 0.38 and 0.26, respectively). Conclusion: Using data from real-world experience, we have identified some risk factors for grade 3/4 CIN, some of which were not included in the current guidelines published for managing CIN. These findings may assist daily clinical practice clinical practice and may provide a rationale for further research in preventing the myelosuppressive side effects of chemotherapy.