Using a simple screening test every one to two years can not only help detect colon cancer at an early stage, it can enable people to avoid colon cancer altogether.

An 18-year study of 46,000 people, reported in The New England Journal of Medicine, showed that the fecal occult blood screening, which individuals can easily administer to themselves, can help people detect colon polyps before they lead to cancer. In the study, the colon cancer rate was reduced by as much as 20 percent in people who did the test.

Colon cancer kills 65,000 people annually in the U.S., making it the leading cause of cancer deaths for men and women after lung cancer.

The fecal occult blood screening costs about $10 to $20 and entails a person collecting two tiny samples of stool from three consecutive bowel movements. The samples are mailed to a lab that tests them for hidden blood. A person who tests positive normally then has a colonoscopy, in which a physician uses a lengthy tubular camera to determine whether the bleeding comes from a polyp, a cancerous growth or another intestinal source.

Researchers have known for some time that the fecal occult blood screening can catch colon cancer at an initial stage, and that such early intervention can make the five-year survival rate as high as 90 percent. By contrast, fourth stage colon cancer yields only an 8 percent survival rate.

Yet few Americans have any colon cancer screening, be it the home self-test or far more expensive hospital procedures, including colonoscopy and sigmoidoscopy (a camera-assisted test similar to a colonoscopy but which only covers the lower few feet of the colon). Researchers estimate that only a quarter to a third of Americans over 50 have had any of the screenings.

The cheaper fecal test is effective, medical experts say, but only if it is taken every year or so. The more expensive scoping tests (which range from about $500 for a sigmoidoscopy to about $1500 for the colonoscopy) can be done less frequently because they are more likely to detect polyps or cancers.

The bottom line from the study is quite simple: if you are 50 or older, a yearly fecal screening is preventive self-care at its best -- easy, inexpensive, private and, very possibly, life-saving.