Microsatellite instability is associated with a better prognosis for gastric cancer patients after curative surgery.
BACKGROUND
Microsatellite instability (MSI) is one of the leading mechanisms for the carcinogenesis of gastric cancer. Its prognostic value is controversial.


METHODS
Between May 1988 and Oct 2003, a total of 214 gastric cancer patients undergoing curative surgery were enrolled, and their MSI statuses were classified as MSI-H (high) or MSI-L/S (low/stable). The clinicopathologic characteristics of MSI-H and MSI-L/S gastric cancers were compared.


RESULTS
The MSI-H tumors accounted for 11.7 % (n = 25) of the 214 total gastric cancers. Although not statistically significant, the MSI-H gastric cancers were more frequently located in the lower third of the stomach (64 % vs. 49.2 %) and were more often the intestinal type (72 % vs. 61.4 %) compared to the MSI-L/S gastric cancers. The MSI-H gastric cancers had a significantly better 5-year overall survival (OS) rate (68 % vs. 47.6 %, p = 0.030) and a trend of a better 3-year disease-free survival rate (71.8 % vs. 55.2 %, p = 0.076) compared to the MSI-L/S gastric cancers. A multivariate analysis revealed that pathologic TNM stage and MSI status were the independent prognostic factors for OS after curative surgery.


CONCLUSIONS
Compared to MSI-L/S tumors, MSI-H tumors are associated with a better OS rate for gastric cancer patients after R0 resection.
Division of General Surgery, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan. s821094@hotmail.com
Wen-Liang
WL
Fang
Shih-Ching
SC
Chang
Yuan-Tzu
YT
Lan
Kuo-Hung
KH
Huang
Jen-Hao
JH
Chen
Su-Shun
SS
Lo
Mao-Chih
MC
Hsieh
Anna Fen-Yau
AF
Li
Chew-Wun
CW
Wu
Shih-Hwa
SH
Chiou
D000230:Adenocarcinoma / Q000235:genetics* / Q000401:mortality / Q000601:surgery; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D011379:Prognosis; D013274:Stomach Neoplasms / Q000235:genetics* / Q000401:mortality / Q000601:surgery; D016019:Survival Analysis; D013624:Taiwan