Microsatellite instability in Japanese vs European American patients with gastric cancer.
BACKGROUND
The stage-stratified survival following gastrectomy for gastric cancer is far better in Japan than in the United States. The process of carcinogenesis may differ in gastric cancers from Japan and the United States, accounting for prognostic differences, as patients of Asian descent treated in United States also exhibit superior survival in comparison with non-Asian patients.


OBJECTIVE
The phenotype of gastric cancer differs between Japanese and American patients.


METHODS
Retrospective case-case (blinded) study.


METHODS
University hospitals in Japan and the United States.


METHODS
We compared the frequency of microsatellite instability (MSI) at 7 loci from formalin-fixed paraffin-embedded gastrectomy specimens, between cases of gastric cancer at Hitachi General Hospital (N = 18) and in US patients of European descent treated in Orange County, Calif (N = 20). Microsatellite instability, Lauren classification, and T stage were determined without knowledge of the country of origin of the specimens.


METHODS
The frequency of MSI in Japanese vs European American gastric cancer specimens.


RESULTS
The frequency of MSI in Japanese gastric carcinoma specimens was higher than in specimens from American patients of European descent (39% vs 20%, respectively). In contrast, a high frequency of MSI was demonstrated in only 3 European American specimens (15% of all specimens in this group). Tumors from Japanese and American men were more likely to demonstrate MSI than those from women (50% vs 5.6%, respectively; P =.004). Among advanced-stage tumors, Japanese specimens were significantly more likely to demonstrate MSI (55%) than European American specimens (7.1%; P =.02). Specimens from Japan and America demonstrating MSI were equally likely to be from men, involve the gastroesophageal junction, and demonstrate intestinal histologic abnormalities.


CONCLUSIONS
Advanced gastric cancers from Japan are more likely to demonstrate MSI. These data warrant a study of larger numbers of patients to assess whether differences in MSI expression correlates with prognostic differences between gastric carcinoma in patients in Japan vs the United States.
Theuer
Charles P
CP
Department of Surgery, University of California, Irvine College of Medicine, USA. cptheuer@uci.edu
Campbell
Brian S
BS
Peel
David J
DJ
Lin
Fritz
F
Carpenter
Philip
P
Ziogas
Argyrios
A
Butler
John A
JA
D000368:Aged; D005060:Europe / Q000208:ethnology; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics*; D013274:Stomach Neoplasms / Q000235:genetics*; D014481:United States