Meat consumption and cancer of the large bowel

Since the major reviews on diet and cancer by the World Cancer Research Fund (WCRF) and by the British Department of Health's Committee on Medical Aspects of Food Policy (COMA) in 1997 and 1998, additional epidemiological studies relating (red) meat consumption and colorectal cancer have been published or found by search. These are collected here. Thirty adequate case-control studies have been published up to 1999 (from 16 different countries). Twenty of them found no significant association of (red) meat with colorectal cancer. Of the remaining 10 studies reporting an association, some obtained statistical significance only in rectal or colon cancers, another only in men, not women, or found a stronger association with pasta and rice, or used an inadequate food list in the food frequency questionnaire. Fifteen cohort studies have now been published. Only in three were significant associations of (red) meat found with colorectal cancer. Two of these positive studies were from the same group in the USA (relative risk 1.7). The results of the third positive study appear to conflict with data from part of the vegetarians follow up mortality study. Here, five groups of vegetarians (in three different countries) with socially matched controls were followed up (total 76 000 people). Mortality from colorectal cancer was not distinguishable between vegetarians and controls. While it is still possible that certain processed meats or sausages (with a variety of added ingredients) or meats cooked at very high temperature carry some risk, the relationship between meats in general and colorectal cancer now looks weaker than the 'probable' status it was judged to have by the WCRF in 1997.