Studies confirm colon cancer screening reduces deaths

There's new evidence that regular screening for colon cancer has long-term benefits.

Testing for blood in the stool reduced the risk of death from colorectal cancer by as much as 32 percent and it seemed to keep the death rate low even after testing stopped, according to one study.

A second found that getting a regular colonoscopy, where a tube is put in the colon to look for and - in some cases - remove abnormal growths, was linked to a 68 percent reduction in risk. It also confirmed that, if no growths are found, people can safely wait 10 years for their next test.

But the findings do not compare the relative merits of the two methods, even though that may be tempting, wrote Drs. Theodore Levin and Douglas Corley in an editorial in the New England Journal of Medicine, where the studies appear.

"Both colonoscopy and fecal occult-blood testing are effective for colorectal cancer screening, and these new studies support current screening guidelines," said the duo, who are based at Kaiser Permanente Medical Centers in California - Levin in Walnut Creek and Antioch and Corley in San Francisco.

"Both tests have been improved since they were used among the participants in either study. However, the two studies are different, which makes direct comparisons of effectiveness difficult."

"These studies don't break new ground, but they put us on more solid footing in recommending colorectal cancer screening by the current methods and, in general, at the current intervals," said Dr. Greg Enders, a gastroenterologist at Fox Chase Cancer Center in Philadelphia, who was not connected with either study.

Colorectal cancer kills over 600,000 people worldwide each year, according to the World Health Organization. The American Cancer Society estimates that the U.S. has about 50,800 deaths per year, with 142,800 new cases annually, a rate that has been declining thanks to screening.

But doctors are still trying to discern how best to screen and how often.

The government-backed U.S. Preventive Services Task Force recommends people between ages 50 and 75 get screened by colonoscopy every 10 years, with a high-sensitivity fecal occult blood test every year or with a sigmoidoscopy every five years in addition to fecal occult blood testing every three years.

The test that looks for blood in the feces has been the safest, cheapest and least complicated. But unless a tumor is releasing blood, the test can miss it. If blood is found, a colonoscopy is done to look for cancer or remove suspicious growths.

For its evaluation of the blood test, a team led by Dr. Aasma Shaukat of the University of Minnesota in Minneapolis looked at records from 46,551 participants in the Minnesota Colon Cancer Control Study who were followed for 30 years.

People were either screened for fecal blood annually, every two years or not at all. However, the formal screening program only spanned two six-year windows. The researchers had no follow-up information on which patients received subsequent screening with the blood test or a colonoscopy.