Meat consumption, particularly of red and processed meat, is one of the most thoroughly studied dietary factors in relation to colon cancer.
However, it is unclear whether meat, red meat, heterocyclic amines (HCA), or polycyclic aromatic hydrocarbons (PAH) are associated with the risk for rectal cancer.
In this study, investigators from the United States evaluated 952 rectal cancer cases and 1205 controls from Utah and Northern California, between 1997 and 2002.
|Increased consumption of well-done red meat increased risk in men.|
|Journal of Nutrition|
The team performed detailed interviews regarding lifestyle, medical history, and diet.
In addition, DNA was extracted from peripheral lymphocytes, and glutathione S-transferase (GST)M1 enzyme and N-acetyl transferase (NAT)2 enzyme genotypes were assessed.
The investigators found that energy and cholesterol intakes were higher in the cases compared to the controls. However, adjustment for confounders accounted for these differences.
They established that increased consumption of well-done red meat (odds ratio (OR) 1.33) was associated with an increased risk for rectal cancer in men.
The team calculated a mutagen index on the basis of reported amount, doneness, and method of cooking meat. This was positively but not significantly associated with risk of rectal cancer for men (OR 1.37).
NAT2-imputed phenotype and GSTM1 did not consistently modify rectal cancer risk associated with meat intake.
Dr Maureen Murtaugh's team concluded, "These data suggest that mutagens such as HCA that form when meat is cooked may be culpable substances in rectal cancer risk, not red meat itself".