K-ras mutations in sera of patients with colorectal neoplasias and long-standing inflammatory bowel disease

Background: About 50% of colorectal carcinomas and adenomas display K-ras mutations, which have also been described in stool or colonic lavage fluid. Moreover, the presence of K-ras mutations in plasma samples originating from patients with colorectal cancer has been reported recently. Methods: DNA was extracted from sera of 16 patients with colorectal carcinomas, 6 with large adenomas, 3 with Crohn disease and 4 with ulcerative colitis. Sera of 20 healthy blood donors served as negative controls. K-ras mutations at the first or second position of codon 12 were detected by an enriched RFLP-PCR method and confirmed by sequencing. Results: Mutations were found in sera of 5 patients with colorectal carcinomas (31%) and 2 patients with long-standing ulcerative pancolitis (50%), but not in patients with adenomas, Crohn disease or the controls. Conclusions: K-ras mutations can be detected in serum samples from patients with manifest colorectal cancer and in patients who display an increased risk for malignant transformation of the colonic mucosa. This observation may have clinical application concerning non-invasive surveillance of these patients. Because of the low sensitivity of this approach it may be useful to combine it with other molecular markers.