CYP1A1 and gastric cancer: CYP1A1, a cytochrome P450 enzyme involved in metabolism of xenobiotics (Androutsopoulos et al., 2009), has been associated with gastric cancer and precancerous gastric cancer as well as lung cancer (Kouri et al., 1982; Zhang et al., 2004; Hidaka et al., 2016; Huang et al., 2021; Sadeghi-Amiri et al., 2021).