Usefulness of Immunohistochemistry for Microsatellite Instability Screening in Gastric Cancer.
OBJECTIVE
The usefulness of immunohistochemistry to screen for the microsatellite instability (MSI) phenotype in gastric cancer remains unclear. Moreover, the prognostic value of MSI phenotypes in gastric cancer has been debated.


METHODS
The clinicopathologic parameters and survival outcomes of 203 MSI-high (MSI-H) and 261 microsatellite-stable (MSS) advanced gastric cancers (AGCs) were compared. Next, we compared the immunohistochemistry results for hMLH1 and hMSH2 with those of a polymerase chain reaction (PCR)-based method. Kaplan-Meier curves and a Cox proportional hazard regression model were used to conduct survival analyses.


RESULTS
The MSI-H AGCs were correlated with older age (p<0.001), female gender (p=0.018), distal location (p<0.001), larger size (p=0.016), and intestinal type (p<0.001). Multivariate analysis revealed that the MSI-H phenotype was an independent favorable factor that was related to overall survival in patients with AGC (p<0.001). Compared with the PCR-based analysis, immunohistochemistry exhibited high sensitivity (91.1%) and specificity (98.5%) in the detection of MSI phenotypes.


CONCLUSIONS
MSI-H gastric cancers have distinct clinicopathologic features and better prognoses, which suggests the necessity of MSI analysis in gastric cancer. Immunohistochemistry can be a useful and reliable screening method in the assessment of MSI status in gastric cancer.
Department of Pathology, Yonsei University College of Medicine, Seoul, Korea.
Yoon Sung
YS
Bae
Department of Pathology, Yonsei University College of Medicine, Seoul, Korea.
Hoguen
H
Kim
Department of Surgery, Yonsei University College of Medicine, Seoul, Korea.
Sung Hoon
SH
Noh
Department of Pathology, Yonsei University College of Medicine, Seoul, Korea.
Hyunki
H
Kim
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000706:statistics & numerical data*; D053208:Kaplan-Meier Estimate; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D012680:Sensitivity and Specificity; D012737:Sex Factors; D013274:Stomach Neoplasms / Q000235:genetics* / Q000401:mortality
Gastric cancer; Immunohistochemistry; Microsatellite instability; hMLH1; hMSH2