Two flavors of macrophages exist depending on function: (1) M1 macrophages, which are classically activated by interferon-γ (IFNγ) or lipopolysaccharide (LPS), facilitate tumor killing through phagocytosis, the release of nitric oxide and reactive oxygen species, as well as proinflammatory cytokines (i.e., IL1, IL6, IL8, IL12, TNFα) [80,81,82], and (2) the IL4 dependent alternatively-activated M2 macrophages, which are anti-inflammatory [83,84]. This evidence concerns the gene IFNG and neoplasm.