FREQUENCY AND CLINICOPATHOLOGICAL ASSOCIATIONS OF RAS MUTATIONS IN COLORECTAL-CANCER IN THE VICTORIAN POPULATION

Background: Mutations in the oncogene ras occur in 20-50% of colorecta l cancers. The presence of these mutations allows screening tests to b e developed based on the identification of mutant DNA in cells derived from cancers. A study of the prevalence and clinicopathological assoc iations of ras mutations was undertaken. Methods: The frequency of mut ations in codons 12 and 13 of the K-ras gene was investigated in 103 c olorectal carcinomas using restriction fragment length polymorphism. R esults: Mutations were detected in 32% (33/103) of the tumours, predom inantly in codon 12 (25/33). No mutations were detected in normal-appe aring mucosa from the same patients. Conclusions: Analysis of the freq uency of ras mutations compared with various independent clinical vari ables revealed a sex-linked relationship between the presence of a ras mutation and nodal status but no correlation with any other clinical parameter was found. The findings suggest that screening tests based o n ms mutation detection may lack sensitivity because of the presence o f mutations in only 32% of tumours.