BIG question marks have been hanging over the future of the National Bowel Cancer Screening Program for some time, but now, research from Canada shows that adopting a different model could boost results, although at a higher cost.

After considering 10 types of colorectal screening strategies, the Canadian research further compared three, including the test currently used in Australia — the high-sensitivity immunochemical faecal occult blood test (FOBT).

By modelling outcomes using Canadian costing figures, colonoscopy was determined to be the most cost-effective of the three ways to screen for colorectal cancer.

A colonoscopy performed once every 10 years would reduce the incidence of bowel cancer by 81% and mortality by 83% compared with no screening in 50-year-old individuals at average risk for colorectal cancer.(1)

In contrast, the immunochemical FOBT was estimated to reduce incidence by 65% and mortality by 74% when performed annually.

This was the same test as that mailed to Australians turning 50 since 1 January 2008, or 55 or 65 since 1 July 2008, up to the end of this year, under the National Bowel Cancer Screening Program.

The third and lowest performing of the strategies was the low-sensitivity, annual guaiac FOBT, associated with a 44% and 55% reduction in incidence and mortality, respectively.

Sydney gastroenterologist Professor Terry Bolin said these study findings were applicable to Australia even though the study was primarily looking for the optimal screening strategy for Canada.

“We did a study some years ago that showed roughly similar numbers,” he said.

“Our study also allowed for the dwell time, that is, the time it takes a polyp to become a cancer, and we found 10-yearly colonoscopy was still as cost-effective as an annual FOBT, but that the yield in terms of mortality reduction was just huge.

“So there is no doubt that if you have the capacity in your country for colonoscopy, that is the way to go.”

He says that while Australia does have the capacity for colonoscopy, implementation will depend on the new government, with funding for the National Bowel Cancer Screening Program set to be finalised this November.

The screening program currently only offers one-off, immunochemical faecal occult blood testing.

“As far as I am aware, funding for the program is off the table, which is tragic, because as many women die of bowel cancer as breast cancer, and it is the only preventable cancer in men. Why something doesn’t happen is beyond me,” he says.

“But if we do continue the project, we need to make some decisions, and the fact 10-yearly colonoscopy is equal to annual FOBT is a persuasive argument to go for colonoscopy, particularly if you are dealing with a health-insured population.”

According to the Canadian study, the incremental cost per quality-adjusted life-year gained for colorectal cancer screening ranged from $611 for an annual immunochemical FOBT, through to $9159 for an annual low-sensitivity guaiac FOBT. For colonoscopy every 10 years, this cost was estimated at $6133.

1. CMAJ 2010; 182: 1307-1313.

Posted 13 September 2010

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