ANAHEIM, CaliforniaHeavy consumption of red meat and processed meats may increase the risk of pancreatic cancer, according to a multiethnic study. The results suggest that carcinogenic substances related to meat preparation, rather than the meat’s inherent fat or cholesterol content, might be responsible for the association.
Meat consumption has been linked to pancreatic cancer in several case-control studies in the past, but the results have been inconsistent, said lead investigator Ute Nöthlings, DrPH, MSE, postdoctoral fellow, Cancer Research Center of Hawaii, University of Hawaii, Honolulu. Data from prospective studies have been lacking as well, she said at the 96th Annual Meeting of the American Association for Cancer Research (abstract 5821).
For this study, researchers from the Cancer Research Center of Hawaii and the University of Southern California examined the associations between meat, other animal products, fat, and cholesterol intake and the risk of pancreatic cancer. The participants were 190,545 men and women of African-American, Japanese-American, Caucasian, Latino, and Native Hawaiian origin who were part of the Multiethnic Cohort Study in Hawaii and Los Angeles.
Dietary intake was assessed at baseline using a quantitative food frequency questionnaire specially designed for use in this multiethnic population. An average follow-up of 7 years yielded 482 incident cases of pancreatic cancer. Pancreatic cancer cases were, on average, 5 years older than noncases, Dr. Nöthlings said.
The researchers found that the heavy consumption of processed meats resulted in the highest risk for pancreatic cancer, after adjusting for age, smoking status, history of diabetes, familial history of pancreatic cancer, and ethnicity. Those who consumed the greatest amount of processed meats had a 67% increase in risk over those participants with the lowest intake of this food category (rate ratio 1.67; 95% CI 1.35 to 2.07; P for trend = .002). A diet rich in pork and red meat also increased pancreatic cancer risk by about 50%, compared with those who ate less meat (P for trend < .0001 and = .0005, respectively).
Consumption of poultry, fish, dairy products, and eggs showed no link to pancreatic cancer risk, nor did overall intake of total fat, saturated fat, or cholesterol. "An analysis of fat and saturated fat intakes showed a significant increase in risk for fats from meat, but not from dairy products, indicating that fat and saturated fat are not likely to contribute to the underlying carcinogenic mechanism," Dr. Nöthlings said.
In particular, she suggested that chemical reactions that
occur during the preparation of processed meats might be
responsible for the association. Such reactions can yield carcinogens, including heterocyclic amines or polycyclic aromatic hydrocarbons.
"Our study is the largest of its kind to demonstrate a link between high consumption of processed meats over long periods of time and pancreatic cancer," she said. "The sample size allowed us to obtain statistically significant risk estimates that support this hypothesis."
Dr. Nöthlings noted that those at highest risk for pancreatic cancer ate about 2 oz of red meat and 1.5 oz of processed meat daily, "but the absolute amount assessed should not be overinterpreted." While there was an increased risk among diabetics, men, and smokers, she said, there was no increased risk with increasing body mass index.
William Nelson, MD, PhD, professor of medicine, John Hopkins University School of Medicine, commented: "This is the strongest epidemiologic study design we have. It answers questions about diet before disease. We know that carcinogens are formed in the curing and processing of meats. The way we cookgrilling and fryingmay add carcinogens to meat." Dr. Nöthlings said that a future analysis of the data is planned to investigate whether food preparation plays a role in pancreatic cancer risk.