K-ras mutations, rectal crypt cells proliferation, and meat consumption inpatients with left-sided colorectal carcinoma

It has been suggested that N-nitroso compounds derived from meat may increa se the risk of K-ras mutations in the human colon, We sought evidence of as sociations between red meat consumption, frequency and type of K-ras mutati ons in resected tumours, and the rate of crypt cell proliferation (CCP) in the normal mucosa of patients with left-sided colorectal carcinoma. Meat co nsumption was assessed by food frequency questionnaire, and CCP was determi ned in rectal biopsies obtained prior to surgery, K-ras mutations in the re sected tumours were determined using a PCR-based oligonucleotide hybridizat ion assay. Fifteen K-ras mutations were detected in tumours from 43 patient s; 13/15 in codon 12, 3/15 in codon 13, and 1/15 in both codons 12 and 13, All mutations were G --> A or G --> T transitions. There was no statistical ly significant difference between intakes of red meat in patients with a K- ras mutation (92.4 +/- 9.7 g/day) and those without (82.3 +/- 7.7 g/day), R ectal CCP was significantly higher in patients than in healthy controls, bu t there was no correlation with meat consumption or K-ras mutation. These d ata do not support the hypothesis that meat consumption is a risk factor fo r acquisition of K-ras mutations during colorectal carcinogenesis. (C) 2000 Lippincott Williams & Wilkins.