Govt opts for 'outdated' bowel cancer test

The Ministry of Health has rejected a bowel cancer screening test that will be adopted in Britain in favour of one labelled "outdated" by a New Zealand expert.

The ministry will use an "immunochemical" blood test in the $24 million, four-year pilot bowel screening programme to start in October for people aged 50 to 74in the Waitemata health district.

The test will use tiny faecal samples to check for microscopic amounts of blood.

People found to be positive will be referred for colonoscopy, a diagnostic investigation of the colon (large intestine).

An earlier version of the faecal blood test, called the "guaiac" test, is used in Britain's national bowel cancer screening programme.

But Britain plans to offer a kind of mini-colonoscopy to replace the faecal blood test and colonoscopy.

This test, called flexible sigmoidoscopy, or FS, will probably be done once every 10 to 20 years, unlike the faecal blood tests which are done every two years.

A British study of the FS found it reduced colorectal cancer mortality by 31 per cent, compared with about 15 per cent for the guaiac test.

One high-quality study of the immunochemical test has been done, finding a 32 per cent mortality reduction for rectal cancer, but no reduction for colon cancer.

Less detailed studies have found reductions of 23 to 81 per cent in colon and rectal cancer.

The ministry said it would stick with the immunochemical test for the pilot.

"The ministry believes that notwithstanding the promising results from the [British FS] study there is currently insufficient information to justify a change of the screening test."

Otago University cancer epidemiologist Associate Professor Brian Cox said yesterday he believed the FS, carried out by nurses and GPs, would be the most practical option.

"The advice the ministry has received has not kept up with international developments over the past 12 months and a lot of money is likely to be wasted by continuing to pursue the immunochemical faecal ... blood test screening."