Animal products and K-ras codon 12 and 13 mutations in colon carcinomas

Abstract

K-ras gene mutations (codons 12 and 13) were determined by PCR-based mutant allele-specific amplification (MASA) in tumour tissue of 185 colon cancer patients: 36␑arboured mutations, of which 82 ere located in codon 12. High intakes of animal protein, calcium and poultry were differently associated with codon 12 and 13 mutations: odds ratios (OR) and 95␌onfidence intervals (95␌I) for codon 12 versus codon 13 were 9.0 (2.0–42), 4.1 (1.4–12) and 15 (1.4–160), respectively. In case–control comparisons, high intakes of animal protein and calcium were positively associated with colon tumours harbouring codon 12 mutations [for animal protein per 17 g, OR (95␌I) = 1.5 (1.0–2.1); for calcium per 459 mg, 1.2 (0.9–1.6)], while inverse associations were observed for tumours with K-ras mutations in codon 13 [for animal protein 0.4 (0.2–1.0); for calcium 0.6 (0.3–1.2)]. Transition and transversion mutations were not differently associated with these dietary factors. These data suggest a different dietary aetiology of colon tumours harbouring K-ras codon 12 and 13 mutations