KRT18 and gastric cancer: The phenotype and karyotyping analysis of CTC subtypes in patients with gastric cancer showed that CTCs with cytokeratins 18-negative/triploidy of chromosome 8 show endogenous resistance to cis-platinum, and CTCs with cytokeratins 18-positive/tetraploidy or over tetraploidy of chromosome 8 show endogenous acquired resistance to cis-platinum [15].