A survey of 1,266 doctors indicates that most of them are not following accepted colon cancer screening guidelines.

The two most common deviations found by the study were doctors recommending that patients start screening before the age of 50 and doctors recommending more frequent screening than suggested by the guidelines. Colonoscopy was the screening test that the most doctors (40%) recommended be used more frequently than prescribed by guidelines.

The study mainly criticizes doctors for starting screening earlier than the age of 50 and for prescribing colonoscopies at more frequent intervals than guidelines suggest. These criticisms may puzzle some patients.

At the time of the survey, there were four major tests that could be used to screen for colon cancer. Which test(s) were best for which patient depended on many factors. The survey found that only 19% of all doctors followed all guidelines for the test(s) that they recommended to their patients.

Most physicians made guideline-consistent recommendations for initiating screening in average risk patients at age 50 and for screening intervals for individual tests.

The researchers used data from a national survey of primary care physicians conducted by the National Cancer Institute in 2006-2007. The researchers looked at the four screening tests that were most common at the time of the survey (sigmoidoscopy, colonoscopy, fecal occult blood test and double-contrast barium enema). Physician recommendations were compared to guidelines that existed at the time of the survey. Two of these guidelines were initiating screenings at age 50, and 10-year intervals between colonoscopies, if colonoscopies were recommended.

The study mainly criticizes doctors for starting screening earlier than the age of 50 and for prescribing colonoscopies at more frequent intervals than guidelines suggest. These criticisms may puzzle some patients. After all, the study seems to be saying that doctors are simply being more cautious than the guidelines suggest.

The study authors explain their outlook as follows. In discussing colonoscopy, they say: "It is also the most expensive CRC screening modality and the most commonly recommended. Overuse of screening is expensive for the health care system, and may result in unnecessary follow-up testing for patients and increased risk of complications."

As a specific example, the researchers mention that increasing the frequency of colonoscopy screenings from every ten years to every five years increases costs and complications with little improvement in survival rates.

The study found that doctors whose recommendations followed the guidelines most closely were younger doctors, board-certified doctors and doctors who used electronic medical records.

An article detailing the study was published online by the Journal of General Internal Medicine on October 14, 2010.

The American Cancer Society's guidelines on checking for colorectal cancer and polyps, as of October 2010, are that starting at age 50, men and women should follow one of the schedules listed below. Which screening schedule is best varies from patient to patient and is best determined by consultation with your doctor.

To Detect Polyps And Cancer (Preferred)
A flexible sigmoidoscopy every five years
OR
A colonoscopy every ten years
OR
A double contrast barium enema once every five years
OR
A CT colonography (virtual colonoscopy) every five years

To Primarily Detect A Cancer
A yearly fecal occult blood test
OR
A yearly fecal immunochemical test
OR
A stool DNA test, frequency currently uncertain.

More information on these schedules is available at the ACS website.