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.