title: K-ras mutation in colorectal cancer: relations to patient age, sex and tumour location.
abstract: DNA from 251 primary tumours obtained from 123 male and 125 female Norwegian patients with colorectal carcinoma was analysed for the presence of K-ras point mutations at codons 12 and 13. Mutations were found in 99 (39%) of the samples. The frequency of K-ras mutations was significantly related to age and sex of the patients, and to the location of the tumours (overall: P = 0.008). K-ras mutations were much less frequent in colonic tumours from male than female patients at younger ages (< 40 years, odds ratio < 0.014). The low frequency might indicate that a different, ras-independent, pathway to neoplasia is dominating in the colon of younger males. In contrast, older men had more mutations than older women (e.g. 90 years, odds ratio = 5.8). An inverse but less pronounced relationship was seen for rectal tumours. The type of mutation was found to be associated to sex of patient and location of tumour. G-->C transversions accounted for 35% of the mutations in rectal tumours from females, in contrast to only 2.5% in the rest of the material (P = 0.0005). This may indicate that there are specific carcinogens acting in this location.
authors.affiliation: Institute of Transplantation Immunology, National Hospital, University of Oslo, Norway.
authors.forename: J
authors.initials: J
authors.lastname: Breivik
authors.forename: G I
authors.initials: GI
authors.lastname: Meling
authors.forename: A
authors.initials: A
authors.lastname: Spurkland
authors.forename: T O
authors.initials: TO
authors.lastname: Rognum
authors.forename: G
authors.initials: G
authors.lastname: Gaudernack
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001483:Base Sequence; D015179:Colorectal Neoplasms / Q000235:genetics*; D005260:Female; D011905:Genes, ras / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D017354:Point Mutation / Q000235:genetics*