The purpose of this study was to evaluate MSI status in sporadic colorectal cancer and to correlate it with clinicopathologic variables.

Total 45 cases of surgically resected colorectal cancers retrospectively were reviewed about clinicopathologic findings and analyzed for micro satellite instability.

The microsatellite instability (MSI) was found in 5 of 45 cases (11.1%) . A significant association was found between MSI+ tumors and location in the right colon (40%), and high histological grade (100.0%), and mucinous phenotype (33.3%). There was no significant difference for age, sex, growth pattern, lymph node metastases, vessel invasion, or Duke's stage.

These data indicate that MSI frequently occur in colorectal cancers of the right side and in tumors with poorly differentiated or mucinous histology.