title: Different genetic pathways to proximal and distal colorectal cancer influenced by sex-related factors.
abstract: Mutations in the k-ras and TP53 genes, as well as microsatellite instability (MIN), are frequent genetic alterations in colorectal carcinomas and represent 3 different mechanisms in the carcinogenic process. Both the incidence of colorectal cancer and the frequency of genetic alterations in such tumours have been related to different clinico-pathological variables, including age and gender of the patient and location of the tumour. A number of studies have also reported associations between different types of genetic alterations. We therefore wanted to explore the relationship between these genetic and clinico-pathological variables using multivariate analysis on material from 282 colorectal carcinomas. Three logistic regression models were constructed: 1) the presence of K-ras mutations was dependent on MIN and age and gender of patient, with an especially low frequency among younger males and in tumours with MIN (overall p = 0.0003); 2) the presence of TP53 mutations was only dependent on tumour location, with a positive association to cancers occurring distally (p = 0.002); and 3) the presence of MIN was dependent on age, gender and K-ras and TP53 mutations, as well as on tumour location. MIN was most frequent among younger male and older female patients, was rare in tumours with K-ras or TP53 mutations and was found almost exclusively in the proximal colon (overall p < 0.0001). Our data confirm that different genetic pathways to colorectal cancer dominate in the proximal and distal segments of the bowel and suggest that the K-ras- and MIN-dependent pathways are influenced by different sex-related factors.
authors.affiliation: Department of Immunology, Institute of Cancer Research, The Norwegian Radium Hospital, Oslo. jbreivik@medisin.uio.no
authors.forename: J
authors.initials: J
authors.lastname: Breivik
authors.forename: R A
authors.initials: RA
authors.lastname: Lothe
authors.forename: G I
authors.initials: GI
authors.lastname: Meling
authors.forename: T O
authors.initials: TO
authors.lastname: Rognum
authors.forename: A L
authors.initials: AL
authors.lastname: Børresen-Dale
authors.forename: G
authors.initials: G
authors.lastname: Gaudernack
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D004273:DNA, Neoplasm / Q000235:genetics; D005260:Female; D016158:Genes, p53; D011905:Genes, ras; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D009154:Mutation; D012044:Regression Analysis; D012737:Sex Factors
chemical_list: D004273:DNA, Neoplasm