Colonoscopy overused in screening

THE federal government’s failure to fully implement national colorectal cancer screening may be driving clinicians to ignore guidelines and refer low-risk patients for colonoscopy, experts suggest.

A study in the Medical Journal of Australia (MJA) this week prompted cancer experts to reiterate calls for expansion of the National Bowel Cancer Screening Program (NBCSP) in order to save the lives of up to 500 Australians per year.

A low 43% uptake of faecal occult blood test (FOBT) kits, currently mailed to all Australians turning 50, 55 and 65, was identified as a key deficiency of the existing program in the study of around 1100 randomly selected individuals in the NSW Hunter region.

It found that among 777 asymptomatic people, 16% had had colonoscopy within the previous five years, of whom 81% were at, or only slightly above, average risk of bowel cancer, making them ineligible under national screening guidelines. 

About one third of at, or slightly above, average risk respondents who had undergone colonoscopy screening had never undertaken FOBT.

In an editorial, leading bowel cancer screening expert Professor Graeme Young and Cancer Council Australia CEO Professor Ian Olver said colonoscopy was increasing by 10% annually but would decrease with a fully implemented FOBT program.

Including everyone older than 50 in FOBT screening would cost another $15 million per year, offset against the $1 billion cost of treating established colorectal cancer.

“We are certainly seeing colonoscopy used as a primary form of screening, which is not recommended by guidelines,” Professor Olver told MO. “If there was a fully implemented program there would be less of this happening because it would be easier to educate GPs and the general public.”

Professor William Sievert, president of the Gastroenterological Society of Australia, said biennial bowel screening was “affordable, cost saving and will save Australian lives. It’s a budgetary no-brainer!” 

Inappropriate colonoscopy screening for low-risk patients “would likely be corrected with confidence in a fully implemented and promoted NBCSP”, he said.

The RACGP’s new representative on the NBCSP advisory committee, West Australian GP and academic Professor Jon Emery, said GPs had been sidelined from the implementation of the program to date.

They may be being influenced by local gastroenterologists who believe that, as in the US, colonoscopy should be the first line of screening, regardless of potential patient risk and reduced cost-effectiveness.

“We don’t really have any data on what is driving these levels of colonoscopy, but it could also be partly patient demand driven by an inaccurate perception of risk due to family history,” he said.

MJA 2012; 196:516-520;490-91