This international, prospective, observational, open-label, pharmaco-epidemiologic study observes cancer patients at risk for chemotherapy-induced febrile neutropenia (FN) who are receiving filgrastim biosimilar (EP2006) for primary or secondary FN prophylaxis to better describe the patient population at risk for FN and treated prophylactically in physician's best clinical judgement with filgrastim biosimilar (EP2006), to describe prophylaxis patterns involving filgrastim biosimilar (EP2006), and to evaluate hematology levels and variability in hematological outcomes, impact on chemotherapy delivery, radiotherapy, surgery, and mortality. Additionally the study aims to identify patient cohorts who are vulnerable to poor response to FN prophylaxis and experience break-through episodes of FN, understand the differences between prophylaxis responders and non-responders, and describe the degree to which prophylaxis of FN is in congruence with guideline recommendations.