Objective: Somatic mutations in the Ki-ras gene are believed to be an important pathogenetic event occurring approximately in the middle of the neoplastic cascade in the colon. These genetic changes have been observed in about 40%of resected colorectal carcinomas and in 20–60%of benign colon adenomas. In this studywe analyzed the presence of Ki-ras gene mutations in bioptic specimens of colorectal tumours and polyps. Material and Methods: We investigated 61 specimens (1–2 mm in diameter) taken from sporadic colorectal carcinomas (N=18), adenomatous polyps (N=19), hyperplastic polyps (N=13), and normal large bowel mucosa (N=11). Detection of mutations in codons 12 and 13 of the Ki-ras gene was performed by a PCR/RFLP method followed by confirmatory sequencing. Results: Ki-ras mutations were found in 8 of 18 (44%) colorectal carcinomas and in 8 of 19 (42%) adenomatous polyps. Mutations were detected neither in the hyperplastic polyps nor in normal large bowel tissue. A GGT to GTT transversion in codon 12, the most frequently found genetic change, was identified in 50% of the Ki-ras mutated carcinomas and 62% of mutated adenomas. Conclusion: Taking into account aggressivity of some Ki-ras mutations, a proper DNA analysis could contribute to improvement of laboratory diagnostics of cancer, especially in subjects at a higher risk for colorectal carcinoma.

        Key words: Ki-ras gene, mutation, colorectal carcinoma, polyp, adenoma, PCR.