Abstract: BACKGROUND ＆ AIM： To explore the significance of mutation of the exon 9 domain of Kai_1/CD82 gene in the progression and metastasis of colorectal cancer (CRC). MATERIALS AND METHODS： The mutation of the domain of exon 9 was detected by using PCR and judged by sequencing in 40 CRC. The deletion of exon 9 was identified by using RT_PCR and validated by sequencing. RESULTS： The mutation in the Kai_1/CD82 gene was found in 18 of 40 colorectal cases (45％).The frequency of mutation was significantly higher in the colorectal tumors with lymphatic metastasis than those without(P<0.05), and in the advanced stage(Dukes C and D) than in the earlier stage(Dukes A and B) of the cancer (P<0.05). However, there was no significant difference of the mutation frequency when stratified by age and sex of the patients, histological type as well as the degree of differentiation of the CRC (P>0.05). CONCLUSION： The mutation of the Kai_1/CD82 gene was associated with the progression and metastasis of CRC. This can be used for assessing the progression and metatasis of colorectal cancer and for guiding clinical therapy.

Key words: colorectal cancer, Kai_1/CD82 gene, mutation, deletion, metastasis