IL6 and cancer: Different cytokines produced by tumor cells lead to an accumulation of leukocytes that synthesize cytokines and cytotoxic mediators including interleukin (IL)-1, IL-6, tumor necrosis factor-α (TNF-α), transforming growth factor-β (TGF-β), and interferons [22,23] that have been linked with the promotion of cancer cell proliferation, growth, and migration as well as with the stimulation of CRP production.