Furthermore, we suggest that the combination of plasma IDH1 levels and DNA methylation levels of SHOX2 and/or PTGER4 showed better efficiency because the overexpression of wild-type IDH1 could produce alpha-ketoglutarate and its subsequent activation of DNA-demethylating enzymes such as TET2 might alter the DNA methylation levels of SHOX2/PTGER4 in NSCLC [46]. Here, SHOX2 is linked to non-small cell lung carcinoma.