Moreover, the nine genes validated in tumor tissues also showed a significantly higher frequency of tumor-specific hypermethylation in NSCLC plasma, as compared with cancer-free plasma, and a 5-gene set (APC, RASSF1A, CDH13, KLK10 and DLEC1) achieved a sensitivity of 83.64 % and a specificity of 74.0 % for cancer diagnosis. Here, DLEC1 is linked to cancer.