PENK and pancreatic neoplasm: SPARC (Secreted Protein Acidic and Rich in Cysteine), UCHL1 (ubiquitin carboxy-terminal hydrolase L1), PENK (proenkephalin), and NPTX2 (neuronal pentraxin 2) are four genes that Sing et al. [243] have found with methylated promoter regions in cfDNA in patients with pancreatic cancer.