1. ¹Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Department of Epidemiology, Maastricht University, PO Box 616, 6200 MD, Maastricht, The Netherlands
2. ²Research Institute Growth and Development (GROW), Department of Pathology, Maastricht University, PO Box 616, 6200 MD, Maastricht, The Netherlands
3. ³NUTRIM, Department of Pathology, Maastricht University, The Netherlands
4. ⁴TNO Nutrition and Food Research, Zeist, The Netherlands

Correspondence: Dr MP Weijenberg, Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Department of Epidemiology, Maastricht University, PO Box 616, 6200 MD, Maastricht, The Netherlands. E-mail: mp.weijenberg@epid.unimaas.nl

Received 3 November 2004; Revised 31 January 2005; Accepted 2 February 2005.

Abstract

Case–cohort analyses were performed on meat and fish consumption in relation to K-ras mutations in 448 colon and 160 rectal cancers that occurred during 7.3 years of follow-up, excluding the first 2.3 years, and 2948 subcohort members of The Netherlands Cohort Study on diet and cancer. Adjusted incidence rate ratios and 95% confidence intervals were computed for colon and rectal cancer and for K-ras mutation status subgroups. Total fresh meat, most types of fresh meat and fish were not associated with colon or rectal cancer, neither overall nor with K-ras mutation status. However, several weak associations were observed for tumours with a wild-type K-ras, including beef and colon tumours, and an inverse association for pork with colon and rectal tumours; for meat products, an increased association was observed with wild-type K-ras tumours in the colon and possibly with G>A transitions in rectal tumours.