Background:
The clinical significance of low frequency microsatellite instability (MSI-L) in gastric cancer has not been well established.
Aim:
To evaluate the clinicopathological features of MSI-L gastric cancer.
Methods:
We investigated microsatellite instability in the 5 di-nucleotide repeat sequences in 210 unselected gastric cancer patients. A high resolution fluorescent microsatellite analysis assay was utilized for the detection of MSI. The clinicopathological variables were compared among different microsatellite status. The overall survival was analyzed by the Kaplan-Meier method. A multivariate analysis was used to identify the prognostic factors and variables that correlate with lymph node metastasis.
Results:
High frequency microsatellite instability (MSI-H), MSI-L and microsatellite stable (MSS) were identified in 10.5%, 10.0% and 79.5% of unselected gastric cancer cases. The MSI-H cases were less invasive and they were also associated with a better overall survival. MSI-L was correlated with more advanced TNM stage, and more frequent lymph node metastasis. The unfavorable prognosis MSI-L was attributed to its correlation with lymphatic invasion.
Conclusions: MSI-L detected by the di-nucleotide markers formed a distinct subcategory of gastric cancer with an aggressive feature that is associated with the lymphatic system, and which may have a poor prognosis. MSI-L may prove beneficial in predicting the clinical impact of gastric cancer.