BAKERSFIELD, Calif. -- The United States government and the American Cancer Society recommend periodic screening for colon cancer among adults ages 50 and older. However, a study has revealed the majority of people aren't receiving regular tests for colon cancer.

Doctors from University Hospitals Case Medical Center examined medical records for more than 150,000 Medicare beneficiaries from 1991 to 2004. In 1998, Medicare began covering colon cancer screening with colonoscopies and other approved tests, but researchers found the coverage did not improve the rate of screening.

In fact, the percentage of patients receiving recommended colon cancer screening dropped from 29 percent before the insurance coverage to 25 percent in the years afterward. Younger, white patients were more likely to be screened than older minorities.

Experts said it's unclear why the screening rates are so low when the benefits are so high -- the survival rate for colon cancer is 90 percent if detected early and just 10 percent when detected late. Officials estimated increased screening would cut the colon cancer death rate in half.