CASC15 and lung cancer: CASC15 is another unfavorable prognostic marker found in multiple tumors, including lung cancer (Lessard et al., 2015; Fernando et al., 2017; He et al., 2017; Yao et al., 2017; Wu et al., 2018; Bai et al., 2019; Li et al., 2019c; Xie and Cheng, 2019; Yu et al., 2019; Liang et al., 2021; Yu et al., 2021).