[Study of microsatellite instability of colotectal cancer and its clinical significance]

To evaluate microsatellite instability (MI) of colorectal cancer in China.

Replication error (RER) status was examined by using 6 microsatellite loci D2S123, D2S119, D13S160, D8S282, D3S1293 and D18S58. The loci were amplified by PCR technique. The PCR products were separated on denatured polyacrylamide gel and then silver stained.

Of the 60 cases of colorectal cancer studied, 20 (33.3%) showed MI, 11 cases (18.3%) were RER positive. In 11 RER-positive cases, 4(36.4%) had family history of malignant tumor, while only 8.2% had positive family history in RER-negative cases (P < 0.05). The RER-positive patients were younger, and their cancer occurred more frequently in the colon with invasive type of growth. There were more cancers in Dukes III and IV in the REF-positive patients. In 5 colorectal cancer cases associated with adenoma, MI was detectable in 4 adenomas.

MI phenotype might be present ubiquitously in sporadic colorectal cancers in China. Its frequency is comparable to that of other reports. MI is a relatively early molecular event in the genesis of colorectal cancers. RER is a useful sign of susceptibility to the development of colorectal cancer.