There are no guarantees, of course, but most of us can lower our chances of getting colon cancer in several ways: don't eat too much red meat, don't get heavy, exercise, and for heaven's sake, don't smoke. Starting at about age 50, regular screening - colonoscopy is increasingly favoured - improves the chances of avoiding colon cancer and also of surviving even if you do get it. Screening works because colon cancer is usually a slow-growing disease that starts with adenomatous polyps, small, protuberant growths inside the colon that may contain precancerous cells. Screening tests are designed to find these polyps so doctors can remove them before they become cancerous.
Starting at about age 50, regular screening improves the chances of avoiding colon cancer.
Reasons we procrastinate
But the fact of the matter is that most of us tend to put off screening tests, perhaps especially so the ones for colon cancer. The faecal occult blood test involves gathering stool samples. Sigmoidoscopy and colonoscopy require cleaned-out colons. The preparation, which involves a heavy-duty laxative and then a lot of time in the bathroom, can be something of an ordeal. Many people say the preparation for the procedure is more unpleasant than the procedure itself.
So-called virtual colonoscopy might be more appealing. This test lets the doctor view the colon from the outside with a CT scanner instead of from the inside with an endoscope, so it's less invasive and can't cause an accidental perforation of the colon, a one-in-a-thousand occurrence with regular colonoscopy. But for now, it still requires a cleaned-out colon, and it remains virtual only if polyps aren't found. If they are, you will need a regular colonoscopy to have them removed. Besides, virtual colonoscopy is still considered experimental and may not be covered by insurance.
As for the other admonitions - cutting back on red meat may not be so difficult. But the gap between word and deed looms especially large when it comes to weight control and exercise.
So we do need easier, more reliable ways of preventing colon cancer, which is the third most common cancer in the United States (about 154,000 new cases a year) and the second most lethal (52,000 deaths annually).
Aspirin is too risky
The daily, low-dose (81- to 325-milligram) aspirin is one possibility. Many people already take aspirin to reduce their risk of having a second heart attack or stroke - or of having their first one if they fall into a high-risk group (a not-very-exclusive club that includes many men over 40 and postmenopausal women). Aspirin also seems to have anticancer properties. In lab and animal experiments, it has prevented the rapid cell division that's associated with cancer. And epidemiologic studies show that people who take aspirin are about half as likely to get colon cancer as those who don't, although the protective effect seems to emerge only after 10 years or more of regular intake.
When aspirin has been put to the test in randomised trials, the outcomes have been mixed - and confusing. One trial that enrolled people who had previously had a polyp found that taking a 325-mg aspirin daily lowered the risk of getting a polyp again. But another trial that compared different daily dosages (81 mg vs. 325 mg) found the smaller amount modestly protective but not the larger one.
In 2007, the U.S. Preventive Services Task Force recommended against taking aspirin - or any other non-steroidal anti-inflammatory drug (Aleve, Motrin, others) - for colon cancer prevention if your colon cancer risk is average. The well-known risks of these drugs (intestinal bleeding, kidney problems, and "bleeding" strokes) outweigh the possible colon cancer protection, the experts decided. Their recommendation didn't address people in a higher risk category, such as those who have had polyps discovered during a screening test.
It's a closer call, but even then use of aspirin isn't routinely recommended. Part of the thinking is that people at high risk should be screened more often anyway, and that those additional tests will find polyps at an early, less dangerous stage.
The gap between word and deed looms especially large when it comes to weight control and exercise.
Still, there's room for exercising some judgment. If a person at high risk for colon cancer is at low risk for complications from aspirin - and would benefit from taking it for other reasons (presumably cardiovascular) - then it's reasonable to at least consider aspirin for reducing colon cancer risk.
Folic acid falters
Another contender for colon cancer prevention-in-a-pill has been folic acid, the synthetic form of folate, which is found naturally in leafy green vegetables and other foods. One of the B vitamins, folic acid wears several hats, all of them important. It's crucial to the development of red blood cells and therefore the prevention of anaemia. In the United States and several other countries, flour and grains are fortified with folic acid because it prevents spina bifida and other birth defects affecting the spinal cord. Along with other B vitamins, folic acid has been tested as a way of reducing the risk of heart attack and stroke; the results are mixed. It has even been tested as a treatment for depression.
On top of all these other credentials, folic acid looks pretty good as an anticancer agent. It's crucial to the creation of DNA, the molecule that genes are made of, so if folic acid is in short supply, aberrations in DNA that could give rise to cancer-causing mutations may develop. Evidence from animal studies hints at cancer protection from folic acid, and epidemiologists have found a connection between low folic acid intake and colon cancer, particularly in people who drink alcohol (the same is true of breast cancer). With all this good news about folic acid rolling in, the investigators conducting the trial that compared aspirin dosages decided to add folic acid to their study. But their report in the June 6, 2007, issue of the Journal of the American Medical Association (JAMA) was not of the good-news variety.
The study volunteers who took folic acid pills (1,000 micrograms daily) were more, not less, likely to get recurrent polyps than the volunteers who took a placebo pill. Furthermore, large polyps were more common in the folic acid group and, generally speaking, large polyps are more likely to develop into cancer than smaller ones.
The researchers also reported that the folic acid group had more of other sorts of cancer, especially prostate cancer (24 in the folic acid group vs. nine in the placebo group).
Soon after these results appeared in JAMA, Tufts University researchers reported in a cancer epidemiology journal that colon cancer rates in the United States and Canada started to go up after folic acid supplementation began in the two countries in the late 1990s. Although the increase could very well be the result of more people getting screened for colon cancer, the Tufts researchers argued that the surge in our folic acid intake thanks to supplementation might also be to blame.
So what's going on? Does folic acid join the growing list of vitamins and minerals (vitamin A, vitamin E, perhaps selenium) that go from being healthful to harmful when taken in large amounts in pill form? No one knows for sure. Indeed, the Tufts researchers went out of their way to emphasise that their findings were food for thought, and far from conclusive. Still, they speculated that perhaps the surplus folic acid in our diets overwhelms systems in the intestine that metabolise the vitamin. Others have theorized that folic acid in certain amounts may prevent colon cancers from forming, but in large amounts may "feed" small, microscopic cancers if they're already there.For all the latest health tips & news from the UAE and Gulf countries, follow us on Twitter and Linkedin, like us on Facebook and subscribe to our YouTube page, which is updated daily.
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