A certain population of pancreatic cancers showed substantially higher methylation levels, although mean methylation levels of cfDNA in five marker genes of normal volunteers and cancer patients were not significantly different (Fig 3A; P = 0.31, 0.98, 0.07, 0.09, and 0.83, in ADAMTS2, HOXA1, PCDH10, SEMA5A, and SPSB4, respectively). This evidence concerns the gene SEMA5A and cancer.