Previously, Miki et al. reported the utility of serosal stamp cytology‐derived DNA samples for molecular analyses.10 They extracted RNA for serosal stamp cytology specimens obtained from patients with gastric cancer and subsequently analyzed the samples by reverse transcription‐PCR to determine the levels of carcinoembryonic antigen (CEA) and cytokeratin 20 (CK20). This evidence concerns the gene KRT20 and gastric cancer.