At present, there have been studies examining the serum levels of CKAP4 in various cancers (Table 3), including hepatocellular carcinoma (Li et al., 2016; Wang et al., 2019), lung cancer (Yanagita et al., 2018), pancreatic cancer (Kimura et al., 2019), and ESCC (Chen et al., 2018). This evidence concerns the gene CKAP4 and lung cancer.