IL6 and neoplasm: Classically activated M1 macrophages mediate several anti-tumor functions by forming reactive oxygen and nitrogen species, secreting pro-inflammatory cytokines [tissue necrosis factor-alpha, (TNF-α) interleukin-6 (IL-6), interferon-gamma (INF-γ)] to recruit tumor-killing leukocytes, or directly phagocytosing tumor cells [72].