Alternatives to colonoscopy for monitoring colorectal cancer risk

By Sally Robertson, B.Sc.Nov 21 2012

Researchers have found that there are effective alternatives to colonoscopy screening for managing people who have received an initial negative colonoscopy result for colorectal cancer.

Rather than continuing further screening with colonoscopy screening every 10 years for such individuals, less risky and more cost-effective rescreening options may suffice, say Amy Knudsen (Massachusetts General Hospital, Boston, USA) and colleagues.

Previous research has shown that the risk for colorectal cancer in people with a negative colonoscopy result is significantly lower than that for unscreened people, leading to the question of whether or not colonoscopy should be repeated 10 years after a negative result, as guidelines currently advise.

Knudsen and team's study suggests that for individuals aged 50 years who have had an initial negative colonoscopy result, rescreening at age 60 years with yearly fecal occult blood testing (FOBT), fecal immunochemical testing (FIT) or 5-yearly computed tomographic colonography (CTC) provides approximately the same benefit in life-years as 10-yearly colonoscopy does but with fewer complications and lower costs.

As reported in the Annals of Internal Medicine, the researchers used the Simulation Model of Colorectal Cancer, a validated microsimulation model of the natural history of colorectal cancer, to evaluate management strategies for an average-risk population with no adenomas or colorectal cancer detected at their first colonoscopy screen at age 50 years.

The team found that rescreening with any method substantially reduced colorectal cancer risk compared with no further screening.

The frequency of lifetime colorectal cancer cases per 1000 years ranged from 7.7 with colonoscopy to 12.6 with FIT when strategies were perfectly adhered to and from 7.7 to 20.9, respectively, when adherence was imperfect. There were 31.3 lifetime cases of colorectal cancer per 1000 years when no further screening procedure was performed.

All screening strategies yielded similar life-years in the perfect adherence scenario, ranging from 30,893 per 1000 persons for FIT to 30,902 per 1000 persons for colonoscopy, giving a difference of 3 days per person. Similarly, with imperfect adherence, the differences in life-years between the rescreening strategies were also small, ranging from 30,865 per 1000 persons for highly sensitive guaiac FOBT to 30,869 per 1000 persons for CTC, a difference of 1 day per person.

Whether the strategies were perfectly adhered to or not, continuing colonoscopy screening was associated with the most perforations and other complications compared with all the other strategies, as well as with higher screening and cancer-related costs.

In the USA, there are not enough trained colonoscopists to perform all of the necessary screening procedures, say Knudsen et al. "Rescreening with methods other than colonoscopy may help solve this shortage because it would free up scarce colonoscopy personnel to perform more primary screening examinations," they say.

The team concludes: "It is reasonable to use other methods to rescreen persons with negative colonoscopy results."

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