Weycker D, Doroff R, Hanau A, et al. - Researchers sought to determine the patterns of pegfilgrastim prophylaxis during the chemotherapy course and associated febrile neutropenia (FN) risks in US clinical practice. From two commercial healthcare claims repositories (January 2010 – March 2016) and Medicare Claims Research Identifiable Files (January 2007–September 2015), they extracted data of 50,778 commercial patients who received 190,622 cycles of chemotherapy and 71,037 Medicare patients who received 271,944 cycles. Notwithstanding clinical practice guidelines, granulocyte colony-stimulating factor prophylaxis was not administered to a large minority of patients, and FN incidence was substantially higher among this subset of the population. This emphasizes the proper use of pegfilgrastim prophylaxis to diminish patient exposure to this potentially fatal but largely preventable complication of myelosuppressive chemotherapy.