Granulocyte (G-CSF) and granulocyte-macrophage stimulating factors (GM-CSF) are substances that bind to hematopoietic stem cells, activating them to profliferate and differentiate into granulocytes and macrophages – the specific cell type of interest. Colony-stimulating factors administered systemically have been evaluated and recommended for patients with cancer for the prevention of infection and febrile neutropenia. CSFs may be used for primary or secondary prophylaxis. In primary prophylaxis, CSFs are administered with the first course of chemotherapy in order to prevent neutropenic sequelae. In secondary prophylaxis, CSFs are used for patients who had febrile neutropenia or infections during a prior course of therapy provided without CSF prophylaxis. NCCN, the American Society of Clinical Oncology, and the European Oncology Research and Treatment  groups all have guidelines regarding the use of prophylactic colony-stimulating factors.