Frequency and clinico-pathological associations of ras mutations in colorectal cancer in the Victorian population.

Background: Mutations in the oncogene ras occur in 20-50% of colorectal cancers. The presence of these mutations allows screening tests to be developed based on the identification of mutant DNA in cells derived from cancers. A study of the prevalence and clinicopathological associations of ras mutations was undertaken.
Methods: The frequency of mutations in codons 12 and 13 of the K-ras gene was investigated in 103 colorectal carcinomas using restriction fragment length polymorphism.
Results: Mutations were detected in 32% (33/103) of the tumours, predominantly in codon 12 (25/33). No mutations were detected in normal-appearing mucosa from the same patients.
Conclusions: Analysis of the frequency of ras mutations compared with various independent clinical variables 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 on ras mutation detection may lack sensitivity because of the presence of mutations in only 32% of tumours.