Pro-inflammatory cytokines such as interleukin 1 (IL-1), interleukin 6 (IL-6), interleukin 8 (IL-8), interleukin 10 (IL-10) as well as transforming growth factor β (TGF-β), and tumor necrosis factor α (TNF-α) are produced by the cells of the tumor microenvironment, playing a key role in cancer initiation, growth, progression, and metastasis [157,158,159,160]. Here, IL6 is linked to cancer.