IL6 and major depressive disorder: Inflammatory cytokines (especially TNF‐α, IL‐1β, IL‐6, and IL‐17) in the brain modulate its downstream inflammatory signaling pathway including NF‐κB, which disturb monoamine metabolism, elevate excitotoxicity, and reduce the release of tropic factors, exerting a profound impact on psychological state, including anxiety and depression in cancer patients.7, 8