CSF1 and neoplasm: It is now known that TAM originate from circulating monocytes from the bone marrow and accumulate around and in the tumor during the first steps of tumor development and are activated by the secretion of chemokines and cytokines such as macrophage-colony stimulating factor (M-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and CCL2 [63,64,65].