Impact of chemotherapy-induced neutropenia (CIN) and febrile neutropenia (FN) on cancer treatment outcomes: An overview about well-established and recently emerging clinical data.

Despite the overwhelming evidence for the role of granulocyte colony stimulating factors (G-CSF) in managing febrile neutropenia (FN) risk, chemotherapy-induced neutropenia (CIN) and/or FN still remain the most common reasons for reducing relative dose intensity (RDI) and/or delaying chemotherapy schedule. The need to maintain RDI to ensure optimal clinical outcomes is one of the key rationales for utilizing G-CSF. There is a high incidence of reduced RDI in both curative and palliative settings, and this observation is especially evidenced in retrospective analyses. Reduced RDI leads to significantly decreased survival outcomes and quality of life in various malignancies at various clinical settings and stages. Beyond its role as a surrogate prognostic marker, high-grade CIN may have an unexpected predictive role in clinical practice, as illustrated by several data relating CIN occurrence with favorable survival outcomes; this may be due to the fact that body surface area (BSA) - based calculation of dose may not fully account for the pharmacokinetics (PK) of cytotoxic drugs and the fact that there may be variability in drug metabolism between patients treated with same chemotherapy regimens.