Higher Screening Rates Credited With Drop in Colorectal Cancer

But not enough people are being tested for the easily preventable disease, experts say

SUNDAY, June 17, 2007 (HealthDay News) -- Colorectal cancer is on the decline in the United States, but doctors aren't declaring victory just yet against the deadly disease.

It's one of the few completely preventable forms of cancer -- but only if people get regular screenings, doctors say.

"Unfortunately, only about half of individuals who should be screened are not up to date in their screenings," said Dr. Durado Brooks, director of colorectal cancer for the American Cancer Society.

The American Cancer Society estimates there will be about 112,340 new cases of colon cancer and 41,420 new cases of rectal cancer in 2007 in the United States. Combined, they will cause about 52,180 deaths.

A recent study by researchers at the University of California, Irvine, found that increased screening for colorectal cancer may have contributed to the disease's decline in the United States between 1988 and 2002. According to the researchers, colorectal cancer decreased from 42.8 cases per 100,000 people in 1988-90 to 38.6 cases per 100,000 in 2000-02.

Meanwhile, there was an 80 percent increased use of colonoscopy to test for the disease by Americans between 1997 and 2002.

Many health experts also credit the "Katie Couric Effect," citing the TV newswoman's nationally televised 2000 colonoscopy, prompting more Americans to get screened for the malignancy.

The falling colorectal cancer rates and the climbing colonoscopy rates are linked, because the disease can be averted by removing polyps in the colon that are known to lead to cancer. Those polyps are found through colonoscopy and other screening methods.

"By finding non-cancerous polyps and removing them, we can actually prevent cancer," Brooks said. "Avoiding the disease is probably the most important reason screening needs to be done."

Beginning at age 50, both men and women should follow one of five screening options, according to the American Cancer Society:

  • A yearly stool blood test or fecal immunochemical test.
  • A flexible sigmoidoscopy every five years.
  • A yearly stool blood test plus flexible sigmoidoscopy every five years.
  • A double contrast barium enema every five years.
  • A colonoscopy every 10 years.

Colonoscopy has been presented as the best option, because polyps can be detected and removed during the same procedure. During a colonoscopy, a slender, lighted tube is inserted through the anus up into the colon, allowing a thorough scan of the organ.

But Dr. Bernard Levin, vice president of cancer prevention at the University of Texas M.D. Anderson Cancer Center in Houston, said the emphasis on a colonoscopy shouldn't keep people from pursuing other forms of screening if colonoscopy isn't available where they live.

Any screening test that gets done is the best, Levin said. "We have to accept that colonoscopy is not available to everybody. Other screening methods should not be considered second-rate," he said.

Other screening methods might also seem more palatable to patients who don't want to be anaesthetized, undergo the cleansing process necessary to prepare themselves for a colonoscopy, or have some other objection to the procedure.

"Some patients absolutely refuse having anything inserted into their body as a screening tool," Brooks said.

Flexible sigmoidoscopy is similar to colonoscopy, but the tube is inserted only into the lower part of the colon, making the procedure less invasive.

In a barium enema screening, a chalky substance is used to partly fill and open up the colon. Air is then pumped in to cause the colon to expand, allowing X-rays to be taken.

An additional screening tool, virtual colonoscopy, could make it easier than ever to be checked. Virtual colonoscopy uses CT scans and computers to produce two- and three-dimensional images of the colon and display them on a screen.

However, Brooks said, it's too soon to tell whether virtual colonoscopy is a dependable means of detecting or preventing colon cancer.

"Right now, virtual colonoscopy is not recommended as a screening tool," he said. "There is a significant body of evidence that supports its usefulness as a test, but it is being evaluated."

Levin decries another misconception about colon cancer, that men are more likely than women to get the disease.

"Over a woman's lifetime, they have the same chance as men," Levin said. "It's not a man's disease."

Those who are screened regularly for colorectal cancer are being met halfway by the medical profession, which is working to improve the quality of its screenings.

For example, a recent study found that doctors are more likely to get better results during a colonoscopy if they spend at least six minutes looking for abnormal growths.

The key is withdrawing the instrument slowly after it has been fully inserted, Levin and Brooks said.

"You have to do a high-quality examination for that examination to be effective," Brooks said. "Doctors who took their time and removed the scope slowly were able to find abnormalities at a rate of three times more compared with doctors who removed the scope at a more rapid rate."

Levin agreed. "If you're not withdrawing slowly enough to see every aspect of the colon, you're short-changing that patient," he said.

More information

To learn more about colorectal cancer, visit the American Cancer Society.

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