Risk factors for chemotherapy-induced neutropenia occurrence in breast cancer patients: data from the INC-EU Prospective Observational European Neutropenia Study.

BACKGROUND: Chemotherapy-induced neutropenia (CIN) places patients at risk of life-threatening infections. While reduction of chemotherapy dose or delay of the subsequent treatment cycle and, consequently, reduction of relative dose intensity (RDI) may limit myelotoxicity, these actions can also impact adversely on treatment outcome and should be avoided in adjuvant settings. PATIENTS AND METHODS: Based on data from 444 breast cancer patients in the INC-EU Prospective Observational European Neutropenia Study, we have evaluated patient-specific and treatment-specific factors that impact on the incidence of grade 4 CIN (absolute neutrophil count <0.5 × 10(9)/L), either during the first or in any cycle of (neo)adjuvant chemotherapy, across a range of regimens and doses.
RESULTS: Using multivariate logistic regression analysis, risk factors for grade 4 CIN were identified as older age, lower weight, higher planned dose intensity of doxorubicin, epirubicin, or docetaxel, higher number of planned cycles, vascular comorbidity, lower baseline white blood cell count, and higher baseline bilirubin. Use of colony-stimulating factor before a neutropenic event occurred, dose delays, and dose reductions were protective against grade 4 CIN.
CONCLUSIONS: By identifying risk factors for grade 4 CIN, CSF prophylaxis may be appropriately targeted to prevent low RDI in patients treated with curative intent.