Well-done Meat Found to Increase Bladder Cancer Risk

According to a large study conducted at the University of Texas MD Anderson Cancer Center and presented at the AACR 101st Annual Meeting 2010, eating well-done meat, especially red meat, may increase the risk of bladder cancer, particularly in individuals with genetic variants in their metabolism.

The study, which took place over 12 years, included 884 patients with histologically confirmed bladder cancer treated at MD Anderson and 878 individuals with no history of cancer. Patients were matched by age (± 5 years), sex, and ethnicity. The researchers, led by Jie Lin, PhD, department of epidemiology, collected dietary and epidemiologic data using structured questionnaires via an in-person interview. Dietary information was gathered using the National Cancer Institute Food Frequency Questionnaire, and individuals were classified into one of four levels based on how much red meat they reported consuming.

Lin and colleagues found that those who consumed the most red meat had approximately one-and-a-half times the risk of developing bladder cancer as those who ate little red meat. Although consumption of beef steaks, pork chops, and bacon significantly increased bladder cancer risk, even chicken and fish conferred significantly increased risk when they were fried. When considering the doneness level of the meats, medium-done red meat and well-done red meat were associated with a 1.46- fold (95% confidence interval [CI], 1.13-1.89) and 1.94-fold (95% CI, 1.52-2.49) increased risk of bladder cancer compared with rare doneness (P<.001 for trend).

“It’s well known that meat cooked at high temperatures generates heterocyclic amines (HCAs) that can cause cancer,” said Lin in a press statement. When the study investigators examined HCA intake in a subset of 177 bladder cancer cases and 306 controls, compared with those in the lowest quartile of meat intake, the odds ratios for the second, third, and fourth quartiles were 1.18 (95% CI, 0.63-2.23), 1.64 (95% CI, 0.89-3.00), and 2.58 (95% CI, 1.43-4.66), respectively (P<.001 for trend). Lin and colleagues also examined the joint effects of red meat and genetic variants in the pathways relevant to HCA metabolism and found the risk associated with high red meat intake was most significant in individuals carrying a high number of unfavorable genotypes in the pathway. When subjects in the lowest quartile of red meat intake and carrying fewer than 6 unfavorable genotypes were compared with subjects whose red meat intake was in the highest quartile and who had 7 or more unfavorable genotypes were at a 4.74-fold increased risk of developing bladder cancer (95% CI, 2.78-8.10; P<.001).

Lin and colleagues concluded that the study results “strongly support that red meat intake and genetic variants in the HCA metabolic pathways jointly influence bladder cancer susceptibility.” They also noted that 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.

AACR Abstract 2825 (http://bit.ly/99qmoY)