TNF and neoplasm: Loss of skeletal muscle mass has been associated with increased circulating levels of pro-inflammatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), as demonstrated in recent clinical studies of gastric and colorectal cancer patients, where elevated IL-6 and TNF-α were linked to accelerated tumor progression, angiogenesis, and impaired antitumor immunity (33–35).