FOLR3 and cancer: In the present study, all NSCLC samples were collected before biopsy, surgery and any cancer related treatment, approximately 80% of the NSCLC cases were at stage I. Our data, therefore, showed a significant association between FOLR3 hypomethylation in peripheral blood and increased the LUSC and LUAD risk of the cases, even at a very early stage (stage I), indicating the altered DNA methylation signatures as a potential biomarker for the early detection of NSCLC.