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. This evidence concerns the gene IL1B and breast cancer.