TNF and major depressive disorder: MDD is associated with higher circulating levels of inflammatory cytokines, such as interleukin (IL)‐6, IL‐8, IL‐1β, TNF‐α, soluble IL‐2 receptor (sIL‐2R), and C‐reactive protein (CRP), which promote cellular proliferation in breast tissue and have also been linked to development of breast cancer.41, 42