Colorectal cancer screening guidelines revised

NEW YORK (Reuters Health) - Updated guidelines from the US Preventive Services Task Force for colorectal cancer (CRC) screening of asymptomatic individuals no longer endorse double-contrast barium enema as a primary test, and no longer recommend routine screening of asymptomatic individuals after age 75 years.

The Task Force commissioned two studies to bring up to date its guideline issued in 2002. The first included a targeted systematic evidence review related to test characteristics and benefits and harms of different screening technologies. The second involved decision analysis using two colorectal cancer microsimulation models to assess health outcomes and resource requirements of available screening modalities.

According to the report in the Annals of Internal Medicine published online on October 6, evidence suggests that population screening programs between the ages of 50 and 75 will be approximately equally effective in terms of life-years gained for any of the three recommended modalities.

The recommended screening modalities are annual high-sensitivity fecal occult blood testing; sigmoidoscopy every 5 years combined with high-sensitivity fecal occult blood testing every 3 years; and screening colonoscopy at intervals of 10 years.

With either of the first two options, positive findings should be followed by colonoscopy.

Study results showed that modern high-sensitivity fecal occult blood testing has a false positive rate of less than 10%.

At this time, the Task Force maintains that evidence is insufficient to permit a recommendation for computed tomographic colonography and fecal DNA assays.

For asymptomatic adults of average risk between ages 76 and 84, evidence suggests that the net benefits of screening are small. On the other hand, "for adults over age 85 years, there is moderate certainty that the benefits of screening do not outweigh the harms."

Efforts to reduce colon cancer deaths "should focus on implementation of strategies that maximize the number of individuals who get screening of some type," the authors say. Given that the acceptability of different types of tests varies among patients, "eliciting patient preferences is one step in improving adherence."

"Ideally," they conclude, "shared decision making between clinicians and patients would incorporate information on local test availability and quality as well as patient preference."

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