Mechanisms Linking Colorectal Cancer to the Consumption of (Processed) Red Meat: A Review

Abstract

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in the world. The vast majority of CRC cases have been linked to environmental causes rather than to heritable genetic changes. Over the last decades, epidemiological evidence linking the consumption of red and, more convincingly, of processed red meat to CRC has accumulated. In parallel, hypotheses on carcinogenic mechanisms underlying an association between CRC and the intake of red and processed red meat have been proposed and investigated in biological studies. The hypotheses that have received most attention until now include (1) the presence of polycyclic aromatic hydrocarbons and heterocyclic aromatic amines, two groups of compounds recognized as carcinogenic, (2) the enhancing effect of (nitrosyl)heme on the formation of carcinogenic N-nitroso compounds and lipid peroxidation. However, none of these hypotheses completely explains the link between red and processed red meat intake and the CRC risk. Consequently, scientists have proposed additional mechanisms or refined their hypotheses. This review first briefly summarizes the development of CRC followed by an in-depth overview and critical discussion of the different potential carcinogenic mechanisms underlying the increased CRC risk associated with the consumption of red and processed red meat.

Keywords:

• Polycyclic aromatic hydrocarbons
• heterocyclic aromatic amines
• N-nitroso compounds
• lipid oxidation
• heme
• N-glycolylneuraminic acid

ACKNOWLEDGMENT

This literature review has been performed within the context of the formulation of a scientific advice on ‘Red meat, processed red meats and the prevention of colorectal cancer’ by the Belgian Superior Health Council. The authors were member of the ad hoc workgroup, and sincerely thank the other members of this workgroup (G. De Backer, S. De Henauw, N. Delzenne, L. Herman, G. Maghuin-Rogister, N. Paquot, M. Peeters and J. Van Camp).

Notes

¹ Although the literature is not always clear, “red meat” in this report refers to home prepared and cooked fresh red meat products (beef, pork, sheep and goat) that have not been subjected to treatments other than cooling, freezing and/or comminution for mixing with other red meats and salt (e.g. ground meat). Processed meat products are defined by the “World Cancer Research Fund/American Institute for Cancer Research” (WCRF/AICR, 2012) as “meat preserved by smoking, curing or salting or by addition of chemical preservatives” and are here more simply specified as “red meats at least preserved by nitrite (and/or nitrate) curing and possibly other treatments.” In the literature, processed meats do clearly (although tacitly) not cover poultry. To prevent possible confusion with definitions of meat covering poultry the term “processed meats” is replaced by “processed red meats” in this review.