October 19, 2012 11:43 am

Two components of red meat increase risk of bladder cancer, American researchers say


TORONTO – Red meat is yet again taking a beating from scientists with new research that suggests two components of the iron-packed protein increase the risk of bladder cancer.

American scientists at the University of Southern California say dietary protein and dietary iron found in red meat may combine to form powerful carcinogens called N-nitroso compounds.

These compounds increase the risk for bladder cancer, especially within people with a specific set of genetics that may leave them less likely to be able to repair the negative effects of the carcinogens, the researchers allege.

Chelsea Catsburg, a doctoral student at the university’s Keck School of Medicine, presented these findings Friday at an international research forum called the Frontiers in Cancer Prevention Research in Los Angeles.

“Individuals at risk for bladder cancer may wish to avoid intake of red and processed meats, especially if they have genetic polymorphisms that reduce DNA repair activity and make them more vulnerable to the effects of carcinogens,” she writes.

Key gene may leave some people more vulnerable than others: research

The researchers initially thought that meat with high levels of amine concentrations, such as salami, increased the risk for bladder cancer.

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They analyzed the health data of 355 bladder cancer cases as well as more than 400 controlled datasets to look at how genetic traits affect our ability to repair damage done to our organs by carcinogens.

Results showed that those with a RAD52 gene were most vulnerable of contracting bladder cancer.

Catsburg and her team say that the results support World Cancer Research Fund recommendations that insist on consumers limiting their red meat intake and to avoid processed meats to reduce the risk of stomach and bowel cancer.

Bladder cancer in Canada

In 2010, Statistics Canada estimated that 7,100 people in Canada were diagnosed with bladder cancer, making it the sixth most common cancer in Canada.

While bladder cancer doesn’t have the profile that other cancers do, such as breast cancer, for example, Dr. Alexandre Zlotta, a medical oncologist at Mount Sinai Hospital, told Global News that it’s one of the most expensive cancers to treat.

“It accounts for nearly $4 billion per year in the U.S. and the figures are roughly a tenth of that in Canada,” he said.

The mortality rate is roughly 40 per cent, which is very high, he notes.
Smoking, inhaling fumes and dyes tend to be the No. 1 link to bladder cancer. Still, large portions (about 40 per cent) of bladder cancers occur without any well-defined risk factors.

Red meat in the spotlight

The study is only one in a series of reports that have vilified red meat.
In March, a Harvard School of Public Health study singled out red meat, linking consumption to an increased risk of death from cardiovascular disease and even cancer.

In that large scale study, 37,700 men and more than 83,000 women were studied over three decades.

Results showed that a single daily serving of unprocessed red meat – about the size of a deck of cards – was linked to a 13 per cent increased risk of death.

Canada Beef, an organization representing domestic and global beef marketing, poked holes in the findings and told consumers that eating red meat within national guidelines is safe.

“Red meat continues to be a healthy part of a balanced diet and nutrition decisions should be based on the total body of evidence, not on single studies that include weak and inconsistent evidence and stand in contrast to other research and to the dietary guidelines for Canadians,” said Karine Gale, nutrition program manager at Canada Beef.

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