Chao A et al. (2005) Meat consumption and risk of colorectal cancer. JAMA 293: 172–182

Red meat is thought to increase the risk of colorectal cancer, but questions remain regarding the magnitude of the association independent of other risk factors, and whether consumption of red or processed meat increases the risk of rectal cancer. In a recent paper published in JAMA, Chao et al. describe their investigation into effects of meat consumption on the risk of colon or rectal cancer in a large, population-based cohort in the US.

As part of the Cancer Prevention Study II, information on meat consumption was collected from a cohort of ∼150,000 individuals in 1982, and again in 1992–1993. Participants were divided into three groups according to their meat intake (low, moderate or high).

During the follow-up period from 1992–1993 until 2001, there were 1,667 incident colorectal cancers. Adjusting for age and energy intake, a higher intake of red and processed meat in 1992–1993 was associated with a higher risk of colon cancer in both men and women. This association was no longer significant, however, when adjusted for other covariates such as physical inactivity and obesity. The risk of distal colon cancer was 50% higher in participants who reported a high intake of processed meat in 1982 and 1992–1993 than in those with a low intake. A similar increase in risk was seen in those with a high ratio of red meat to poultry and fish. The risk of rectal cancer was elevated in those with a high consumption of red meat reported at both time points or in 1992–1993 only.

Chao et al. conclude that long-term meat intake is an important component of cancer risk, and that red and processed meat appear to be associated with tumors in the distal colon and rectum.