CYP2D6 and esophageal squamous cell carcinoma: Studies have indicated that polymorphisms of CYP2D6 imposed an increased risk of breast cancer and esophageal squamous cell carcinoma in those people with a family history of cancers.43, 44 Zienolddiny S et al found that CYP2D6 and CYP1B1 increased genetic susceptibility to NSCLC.45 In addition, Lee JY et al showed that hydroxychloroquine metabolism was related to CYP2D6 rs1065852 polymorphisms.46