[K-ras gene mutations in adenomas from familial adenomatous polyposis]

A 18-year-old woman underwent total colectomy for familial adenomatous polyposis. In order to clarify the significance of K-ras mutations in early colorectal carcinogenesis, K-ras mutations were analyzed in multiple adenomas by PCR-SSCP method. A total of 256 adenomas were found throughout the entire colon and rectum, and the distribution was a sparse type. The correlation between K-ras gene and clinicopathological factors was examined in 90 adenomas. There was no correlation among K-ras mutations and anatomical distribution, or morphological classification, but K-ras mutation was more frequent in severe compared with slight atypia. We investigated the correlation between the size of adenoma in the horizontal and vertical directions and K-ras mutation. K-ras mutation was more frequent in the horizontal size greater than 6 mm in diameter, and also more frequent in vertical size greater than 20 mm in height. It was concluded that the adenomas detecting K-ras mutations might have proliferating potential, and would be applied to determine polypectomy.