CYP2A6 and gastric cancer: CYP2A6 polymorphisms are also associated with a variety of cancers, including lung cancer, gastric cancer, and bladder cancer (Ezzeldin et al., 2018; Abudushataer et al., 2020; Kumondai et al., 2016), and the aromatase inhibitor letrozole is metabolized by CYP2A6 and is commonly used to treat hormone receptor-positive early breast cancer (Puszkiel et al., 2024).