"To quantify intakes of HCAs, we began three or four years ago to gather information on meat-cooking methods and doneness level, and then used a program developed by the NCI to estimate intakes of three major HCAs," Lin said. "These data gave important information about the relationship between HCAs and bladder cancer."

Genetic variants increase incidenceTo take the investigation a step further, researchers analyzed each participant's DNA to find if it contained genetic variants in the HCA metabolism pathways that may interact with red meat intake to increase the risk of cancer.

People with seven or more unfavorable genotypes as well as high red-meat intake were at almost five times the risk of bladder cancer.

"This research reinforces the relationship between diet and cancer," said Xifeng Wu, M.D., Ph.D., professor in M. D. Anderson's Department of Epidemiology and lead author on the study. "These results strongly support what we suspected: people, who eat a lot of red meat, particularly well-done red meat, such as fried or barbecued, seem to have a higher likelihood of bladder cancer. This effect is compounded if they carry high unfavorable genotypes in the HCA-metabolism pathway."

Wu said this research is a step toward a future in which a comprehensive cancer-risk prediction model will integrate environmental, diet and genetic risk factors to predict an individual's chances of developing cancer.

SOURCE The University of Texas M. D. Anderson Cancer Center