The Family Health Guide

How to lower your risk for colon cancer

How to lower your risk for colon cancer

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, don't smoke, and get some exercise.

Starting at about age 50, regular screening — colonoscopy is increasingly favored — improves the chances of avoiding colon cancer and also of surviving even if you do get it. Screening tests are designed to find these polyps so doctors can remove them before they become cancerous.

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 fecal occult blood test involves gathering stool samples. Sigmoidoscopy and colonoscopy require cleaned-out colons.

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 may not be covered by insurance.

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). Here are some tips to help reduce your risk:

Seven tips about what will and won't lower your risk

  1. Cut back on the red and processed meat. The studies don't line up perfectly, but many point to increased colon cancer risk among people who eat a lot of red (beef, lamb, pork) and processed meat (bacon, ham, hot dogs, sausage, and so on). Why red meat might cause colon cancer is unclear. Some studies suggest that the heme iron it contains promotes cell division and cancerous growth.
  2. Stay active. Whether it is on or off the job, physical activity seems to protect against colon cancer. Some studies suggest that you'll get even more protection if you exercise vigorously.
  3. Stay slender. Harvard studies identified a connection between obesity and colon cancer in 1995. Some nuances have emerged since. Obese men of all ages are at risk, but for women, premenopausal more than postmenopausal obesity is the danger.
  4. Adequate calcium intake is good enough for most. High milk and calcium consumption have been linked to lower colon cancer risk in epidemiologic studies. And one important trial showed that in people who'd already had a polyp removed, taking 3,000 mg of calcium carbonate daily reduced the risk of recurrence by 20%. But when daily calcium (1,000 mg) and vitamin D (400 IU) supplements were tested, they had no effect on colon cancer rates. Men are expressly advised by the American Cancer Society not to get too much calcium (1,500 mg or more daily) because large amounts may increase prostate cancer risk. The bottom line: People who have had polyps should talk to their doctors about taking a calcium supplement.
  5. Nothing special about fiber. Loading up on fiber was once thought to be our best defense against colon cancer. No more. In clinical trials, fiber hasn't worked to reduce recurrent polyps, and the epidemiological evidence that it protects against first-time polyps is uneven.
  6. Hormone therapy isn't worth the other risks. In the Women's Health Initiative study, postmenopausal women who took an estrogen-progestin combination lowered their risk for colorectal cancer by 44%. But hormone therapy has other risks associated with it, so it's not recommended for colon cancer prevention.
  7. Get screened. The American Cancer Society recommends that people at average risk get their first screening test at age 50. How often screening tests need to be done depends, of course, on whether anything suspicious is found.

December 2007 update

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