Red meat may up bowel cancer risk

Washington - High levels of iron may be one reason why eating red meat raises the risk of bowel cancer, scientists claim.

The researchers found that iron may switch on the disease process via a faulty gene in the gut, which would normally resist the disease.

Red meat contains huge amounts of iron and is also known to increase the likelihood of bowel cancer.

The discovery could lead to new treatments that ‘mop up’ iron in the bowel in people who develop cells affected by the defective gene.

In studies of mice, researchers found that susceptibility to bowel cancer was strongly influenced both by iron and a gene called APC.

When the APC gene was faulty, mice with a high iron intake were two to three times more likely to develop the disease.

Those mice who were fed a low iron diet remained cancer free even if the gene was defective, but when it functioned normally, high iron levels did no harm.

“We’ve made a huge step in understanding how bowel cancer develops. The APC gene is faulty in around eight out of 10 bowel cancers but until now we haven’t known how this causes the disease,” the Daily Mail quoted lead scientist Professor Owen Sansom, deputy director of the Cancer Research UK Institute in Glasgow, as saying.

“It’s clear that iron is playing a critical role in controlling the development of bowel cancer in people with a faulty APC gene.

“And, intriguingly, our study shows that even very high levels of iron in the diet don’t cause cancer by itself, but rely on the APC gene,” Sansom said.

Each year, more than 41,000 people in the UK are diagnosed with bowel cancer and around 16,000 succumb to the disease.

Previously, researchers had estimated that red meat contributes to around 17,000 cases of bowel cancer per year, based on two different dietary factors thought to play a part in promoting bowel cancer because a substance called haem, can damage the lining of the colon, while burning meat produces cancer-causing compounds.

The latest study proposes another mechanism that, if confirmed in people, might help explain why people’s risk of bowel cancer increases with age.

Over time, cells in the bowel would be increasingly likely to develop APC gene faults and thus react to iron in the diet.

Researchers said that when the APC gene doesn’t work, iron is allowed to build up in the cells lining the gut.

This activates a genetic cancer ‘switch’ called want that causes cells to multiply out of control.

According to the report, the consumption of iron also aids the growth of cells with defective APC over time.

“Our results also suggest that iron could be raising the risk of bowel cancer by increasing the number of cells in the bowel with APC faults,” co-author Dr Chris Tselepis, a Cancer Research UK scientist at the University of Birmingham, said.

“The more of these cells in the bowel, the greater the chance that one of these will become a starting point for cancer. We’re now planning to develop treatments that reduce the amount of iron in the bowel and so could lower the risk of developing bowel cancer.

“We hope to start using these in trials in the next few years in people who are at a greater risk,” Tselepis added.

The study was recently published in the journal Cell.