Many colon cancer patients aren't getting the screenings recommended after surgery to make sure the disease hasn't returned, new research shows.

Only about 40 percent of the 4,426 older patients in the study got all the doctor visits, blood tests and the colonoscopy advised in the three years after cancer surgery, according to the results released Monday by the journal Cancer.

While nearly all made the doctor visits and almost three-quarters got a colonoscopy, many didn't get the blood tests that can signal a return of colon cancer, according to the researchers at University Hospitals Case Medical Center in Cleveland.

Whether doctors didn't offer the tests or patients failed to get them isn't known, said Dr. Gregory Cooper, who led the study. He said perhaps the follow-up care was being provided by doctors who aren't specialists and who aren't familiar with the guidelines.

"I would probably put most of the blame on the providers," said Cooper, a gastroenterologist at the hospital.

About 149,000 Americans are expected to be diagnosed with colorectal cancer this year. Survival after five years varies from 90 percent for cancer that hasn't spread to 10 percent for advanced cases.

Cooper and his colleagues used a federal database of cancer cases and Medicare records for patients to see if the guidelines were being followed. They focused on those 66 and older with less advanced cancer who had surgery that could cure them.

Patients were tracked for three years, beginning six months after surgery. When the study began in 2000, the minimum guidelines called for at least two doctor visits a year, twice yearly blood tests for two years and a colonoscopy within three years. Cooper said a colonoscopy is now recommended in the first year.

Overall, 60 percent of the patients didn't meet the guidelines. Of those who did, more than half actually got advanced medical scans like CT scans and PET scans that are not recommended for routine screening. The scans could have been done because of signs or symptoms of a recurrence but the researchers said they suspect they were done for routine follow-up.

There was less screening among older age groups, African-Americans and those with other health problems.

"Quite honestly, I'm sorry to say, I'm not surprised about the findings," said Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society, which funded the study. Despite advanced medical technology, "our ability to deliver the recommended care to patients has left something to be desired."

With the information resources available today, he said patients can take an active role in their follow-up care and make sure that they are getting the screenings they need.