title: Rapidly growing early gastric cancer with microsatellite instability.
abstract: A 77-year-old man underwent gastrointestinal endoscopy that revealed a small flat elevated lesion in the gastric antrum. Endoscopically, we assessed the tumor as intramucosal cancer or adenoma, and biopsy specimens were diagnosed as showing borderline malignancy. At the second examination, performed 6 months later, the elevated lesion had grown, showing remarkable changes in its appearance, and a diagnosis of adenocarcinoma was confirmed pathologically. The patient underwent distal gastrectomy about 8 months after the first examination, and the tumor in the resected specimens showed a moderately differentiated adenocarcinoma invading through the entire submucosal layer, with metastasis to a regional lymph node. Microsatellite analysis of this early gastric cancer disclosed mutations in all six markers examined, indicating high-level microsatellite instability (MSI-H). The tumor also showed frameshift mutations of TGFbetaRII and BAXgenes, as well as hypermethylation of the hMLH1promoter. These results suggest that a deficiency of the mismatch repair system played a critical role in the progression of this cancer.
authors.affiliation: First Department of Internal Medicine, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yamashita
authors.forename: Norihiro
authors.initials: N
authors.lastname: Kato
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Takahashi
authors.forename: Haruo
authors.initials: H
authors.lastname: Shimizu
authors.forename: Hiromu
authors.initials: H
authors.lastname: Suzuki
authors.forename: Satoshi
authors.initials: S
authors.lastname: Motoya
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Arimura
authors.forename: Takao
authors.initials: T
authors.lastname: Endo
authors.forename: Hideki
authors.initials: H
authors.lastname: Ura
authors.forename: Shingo
authors.initials: S
authors.lastname: Ichimiya
authors.forename: Kohzoh
authors.initials: K
authors.lastname: Imai
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics*; D000368:Aged; D016368:Frameshift Mutation; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics*; D009154:Mutation; D011518:Proto-Oncogene Proteins / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2; D013274:Stomach Neoplasms / Q000235:genetics*; D016212:Transforming Growth Factor beta / Q000235:genetics; D051028:bcl-2-Associated X Protein
chemical_list: D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016212:Transforming Growth Factor beta; D051028:bcl-2-Associated X Protein