CRTAC1 and lung adenocarcinoma: The three candidate genes detected in this study were CRTAC1, BATF2, and CTHRC1. Evidence shows that cartilage acidic protein 1 (CRTAC1) is related to various malignancies, including bladder cancer and lung adenocarcinoma, by inhibiting the cell proliferation, migration, invasion, and epithelial–mesenchymal transition processes (Yang et al., 2021; Yu et al., 2021).