Although nicotine is not classified as a carcinogen, it is the main addictive component of tobacco and promotes the development of cancers such as lung, head and neck, pancreatic, gastric, colon, breast, and bladder by inducing genotoxic DNA damage, activating nAChR signaling to enhance proliferation and metastasis, and suppressing anti‐tumor immunity [5, 6, 59]. Here, CHRNA4 is linked to cancer.