Παρασκευή, 13 Νοεμβρίου 2015

MEAT CONSUMPTION AND INCREASED RENAL CANCER RISK

Diets high in meat may lead to an increased risk of developing renal cell carcinoma through intake of carcinogenic compounds created by certain cooking techniques, such as barbecuing and pan-frying. As part of a new study from The University of Texas MD Anderson Cancer Center, published by Melkonian et al in Cancer, researchers also discovered that individuals with specific genetic mutations are more susceptible to the harmful compounds created when cooking at high temperatures.
The incidence of renal cell carcinoma has been rising for several decades, and many suggest that a Western diet is partially to blame. One of the proposed culprits of a Western diet is higher-than-average meat consumption, which has been linked to an increased cancer risk. However, it has not always been clear why eating more meat elevates cancer risk, explained Stephanie Melkonian, PhD, Postdoctoral Fellow in Epidemiology at MD Anderson.
A possible mechanism could be ingestion of meat-cooking mutagens, harmful compounds created when the meat is cooked in certain way. Cooking meat at high temperatures or over an open flame, such as when barbecuing or pan-frying, is known to result in the formation of carcinogens, including 2-amino-1-methyl-6-phenyl-imidazo(4,5-b) pyridine (PhIP) and amino-3,8-dimethylimidazo(4,5-f) quinoxaline (MeIQx).
The kidney is a biochemically active organ responsible for filtering many harmful toxins from the body, and therefore it makes sense to investigate the effects of dietary intake, including carcinogens, on kidney cancer risk, said Dr. Melkonian.
Study Details
To better characterize factors contributing to kidney cancer risk, the researchers surveyed the eating patterns and collected genetic information from 659 MD Anderson patients newly diagnosed with renal cell carcinoma and 699 healthy subjects recruited from the community. Based on survey responses, the researchers estimated meat consumption and exposure to meat-cooking mutagens with the help of a National Cancer Institute database. 
“We found elevated renal cell carcinoma risk associated with both meat intake and meat-cooking mutagens, suggesting an independent effect of meat-cooking mutagens on renal cell carcinoma risk,” said Xifeng Wu, MD, PhD, Professor of Epidemiology at MD Anderson.
Specifically, the results show that patients with kidney cancer consumed more red and white meat compared with healthy individuals. Additionally, the researchers identified a 54% increased risk associated with PhIP intake and a nearly twofold increase associated with MeIQx intake.
The results suggest that cooking method is an important factor contributing to the elevated renal cell carcinoma risk associated with consuming more meat, as both red and white meat resulted in increased risk, explained Dr. Wu.
Genetic Component
This study was also the first to investigate connections between genetic risk factors and intake of meat-cooking mutagens for renal cell carcinoma. “By analyzing genes known to be associated with renal cell carcinoma risk, we found that high intake of these carcinogens may be particularly meaningful for a certain subgroup of the population,” said Dr. Melkonian.
Individuals with variations in the gene ITPR2 were more vulnerable to the effects of consuming PhIP. As this gene has previously been associated with kidney cancer and obesity risk, the results suggest this association may be partially explained by exposure to meat-cooking mutagens. Future experiments will seek to clarify the mechanisms linking mutagen intake and genetic susceptibility.
Further Research Needed
The researchers cannot make specific recommendations regarding acceptable amounts of meat intake or exposure to meat-cooking mutagens based on the current study. Exposure and consumption were analyzed on a relative, rather than absolute, scale, and future studies will be needed to determine appropriate dietary intake.
“Our findings support reducing consumption of meat, especially meat cooked at high temperatures or over an open flame, as a public health intervention to reduce renal cell carcinoma risk and burden,” said Dr. Wu.
The researchers do not suggest that individuals should remove meats completely from their diets but rather consume it in moderation, as part of a well-balanced diet, complete with fruits and vegetables. When grilling or pan-frying meat, try to avoid charring it as much as possible, suggested the researchers.
Dr. Wu is the corresponding author of the Cancer article.
The study was supported by the National Institutes of Health, Center for Translational and Public Health Genomics, Duncan Family Institute for Cancer Prevention, The University of Texas MD Anderson Cancer Center, and the NCI R25T Postdoctoral Fellowship in Cancer Prevention.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.

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