(Health.com) -- Cardiologists and other doctors
already view artery-clogging red meat as a villain, and they now have
another reason to urge their patients to steer clear: A new study has
found that men have a higher risk of developing aggressive prostate
cancer if they consume a lot of ground beef and other red meat --
especially if the meat is grilled or well-done.
The men in the study who ate about two servings of hamburger or meat
loaf per week were more than twice as likely to have been diagnosed with
aggressive prostate cancer as the men who ate none. But most of that
increase in risk can be attributed to how the meat was cooked.
When the researchers looked only at the members of the burger-loving
group who ate their meat grilled or barbecued, the numbers told a
different story: The men who preferred their burgers well-done had
double the cancer risk, while those who liked them medium (or rarer) had
a negligible increase in risk -- just 12 percent. A similar pattern was
seen with grilled or barbecued steak.
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"This is another piece of evidence for the notion that red meat,
particularly grilled meat, contains carcinogens that may relate to
prostate cancer," says Ronald D. Ennis, M.D., director of radiation
oncology at St. Luke's -- Roosevelt Hospital Center, in New York City,
who was not involved in the study.
When meat is cooked -- and charred -- at high temperatures over an
open flame, a reaction occurs that causes the formation of two
chemicals: heterocyclic amines (HCAs) and polycyclic aromatic
hydrocarbons (PAHs). In animal studies, these chemicals have been shown
to cause several types of cancer, including prostate cancer.
Although by now it is well established that red meat increases the
risk of heart disease and colorectal cancer, its role in prostate cancer
has been less clear. Numerous studies have investigated a possible link
between meat consumption and prostate-cancer risk, but the results have
been inconsistent.
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"This study not only associates red meat with a risk of prostate
cancer but it takes it a little bit forward by looking at the method of
cooking and the degree of cooking," says Lee Richstone, M.D., an
associate professor of surgery and a prostate-cancer specialist at the
Smith Institute of Urology, in New Hyde Park, N.Y. "It helps contribute
to our understanding of a potential mechanism in the form of [HCAs] and
[PAHs]."
In the study, which was published this week in the journal PLoS One,
researchers at the University of California, San Francisco compared
about 500 men who recently had been diagnosed with aggressive prostate
cancer to a cancer-free group of similar size who served as controls.
All of the participants filled out detailed questionnaires about their
diets over the previous year, including the amount of meat they ate and
how it was prepared.
Men who ate the most ground beef were 2.3 times more likely than men
who ate none to have aggressive prostate cancer. Higher consumption of
fatty lunchmeats (such as salami) and liver was also associated with an
increase in cancer risk. On the other hand, poultry, bacon, and low-fat
hot dogs and sausages appeared to have little influence on cancer risk.
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The study "certainly supports the notion that these types of foods may be harmful in some ways," Ennis says.
Close to one-fifth of U.S. men will at some point in their lives
develop prostate cancer, which ranges in severity from benign tumors
that need little or no treatment to very aggressive forms that are
usually deadly. Age, family history, and genetics all have been shown to
increase risk. The evidence for environmental risk factors -- including
diet -- is less clear, though researchers have long suspected they play
a role because of the wide geographical variation in prostate-cancer
rates.
The study is far from airtight. The data on meat consumption relied
on the memory of the participants, for instance. And although the
researchers took into account several known risk factors for prostate
cancer (such as family history, smoking, and body mass index), it's
possible that other unidentified factors contributed to the apparent
link between meat consumption and cancer risk.
Still, the findings are compelling enough that men should consider exercising "moderation and caution," Richstone says.
"There's an expanding and building body of literature that does point
to this type of connection, and I think papers like this make for a
stronger and stronger argument that men need to moderate their intake of
highly cooked meat," he says.
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