Evidence for extending colonoscopy schedule limited

Extending the recommended time between surveillance colonoscopies from 5 years to 10 years for people who have had precursor lesions, such as polyps, removed may increase the risk of advanced neoplasia by 60%, according to research involving Flinders University published by the Medical Journal of Australia.

“Until recently, the Australian guidelines recommended surveillance colonoscopy 5 years after a finding of non-advanced adenoma, but follow-up at 10 years is now recommended for most patients,” wrote the researchers, led by Dr Zaki Hamarneh, from Flinders Medical Centre in Adelaide, and colleagues.

“The evidence supporting the change in timing is limited.”

Hamarneh and colleagues analysed data from patients enrolled in a South Australian surveillance colonoscopy program who had findings of non-advanced adenoma during 1999–2016 and subsequently underwent surveillance colonoscopy, to investigate the incidence of advanced neoplasia (colorectal cancer or advanced adenoma) at surveillance colonoscopy following removal of non-advanced adenoma; and to determine whether the time interval before surveillance colonoscopy influences the likelihood of advanced neoplasia.

“We found that the incidence of advanced neoplasia following removal of non-advanced adenoma was 19% at five years and 30% at 10 years; applying the more restricted definition of advanced neoplasia used outside Australia, the estimated incidence was 10% at five years and 23% 10 years after removal of non-advanced adenoma,” Hamarneh and colleagues reported.

“Increasing the colonoscopy surveillance interval from five to 10 years would therefore increase the incidence of advanced neoplasia at surveillance by 60% (Australian definition) or 130% (overseas definition).

“As stated in the most recent Australian surveillance guidelines, one needs to consider the quality of the initial colonoscopy, patient risk factors, and the results of other tests, such as interval faecal immunochemical tests, before lengthening the interval between colonoscopies.

“It is also important to balance the risks of colonoscopy against the benefits of reducing the risk of advanced neoplasia.

“Finally, more evidence about the safety of different surveillance intervals in clinical practice is needed to guide clinical care for people at elevated risk of colorectal cancer,” Hamarneh and colleagues concluded.

“The influence of the surveillance time interval on the risk of advanced neoplasia after non-advanced adenoma removal” by Zaki Hamarneh, Charles Cock, Graeme P Young AM, Peter A Bampton, Robert Fraser, Fang LI Ang, Feruza Kholmurodova, and Erin L Symonds has been published in the Medical Journal of Australia. DOI: 10.5694/mja2.51222. The study was funded by the Flinders Foundation.

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