Should bowel screening start at 45?

New guidelines recommend Australians get their free poo kits five years earlier.

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Updated NHMRC guidelines say bowel cancer screening should start at age 45, and Australians should be allowed to request screening as young as 40. 

But dropping the age from 50, which would bring us in line with US guidelines, has been hotly debated. Critics argue research doesn’t support the move, and even the new guideline recommendation summary notes the evidence is “weak”.  

However, bowel cancer rates in younger people have been climbing for 30 years, with one in nine diagnoses (1716 per year) occurring in those under 50. People in their 40s account for 56% of new cases and 64% of bowel cancer deaths under 50.  

The guidelines have been developed by the Cancer Council Australia and approved by the NHMRC.

Focusing on this age group can “really make a difference,” said Mr Julien Wiggins, CEO of Bowel Cancer Australia.  

“The majority are presenting to GPs with symptoms. And by that stage it’s advanced, typically more aggressive cancer, stage III and IV, [with a] terminal prognosis.”  

The current screening program remains unchanged, and a spokesperson for the National Bowel Cancer Screening Program said any modifications required government consideration. ? 

The Department of Health and Aged Care said it was “carefully considering the implications of the recommendation in the updated Guidelines to lower the eligible age of the NBSCP to 45 years, including the costs and flow on implications for the broader health system”. 

While awareness of bowel cancer has been increasing, participation rates for the existing program are not high (around 40-43%). But Mr Wiggins said that didn’t reflect the total number of people taking some action, aside from returning the test kit in the mail, to screen for bowel cancer.  

“The best test is the one that gets done. People who have colonoscopies, for example, of which there’s around about 800,000 a year in this country, are not included in that rate.” 

While overall participation rates may drop further with the inclusion of around 1.6 million younger people added to the screening pool, Mr Wiggins said the focus should be on its overall effect.  

“If you’re looking at cancers being detected in the 50-55 age group, chances were the polyp or cancer was present in their late 40s, because it takes five to 10 years to grow. I’m hopeful that we will pick them up earlier in that 45-49 bracket,” Mr Wiggins said.  

Despite growing rates of cancer in the younger age bracket, there was a lack of research into how screening programs would affect outcomes – and in fact there were few randomised controlled trials of bowel screening programs overall, Mr Wiggins said.  

“Crafting guidelines in that sort of vacuum of evidence isn’t the easiest of things to accomplish.”  

But this lack of Grade A evidence was not unusual, he pointed out. In fact, around 30% of colorectal cancer guidelines, and 19% of all Australian clinical practice guidelines, are consensus-based, according to a 2019 analysis published in the RACP’s Internal Medicine Journal. International guidelines were similar, they found. 

Another hurdle for adoption of the NHMRC guidelines is cost.  

A 2021 review of the program by Deloitte found screening people aged 45-74 “was found to be more cost-effective than the current target age range from a societal perspective ($1381 per DALY [disability-adjusted life years] avoided), but less cost-effective from a healthcare system perspective ($9936 per DALY avoided)”. 

“There was a marginal difference between starting screening at age 45 or 50. Deciding which entry age is most cost-effective depends on the extent of value placed on a societal perspective versus a healthcare system perspective,” the review said. 

GPs will be particularly affected by changes to the two-year screening program.  

“It’s been known for some time, the biggest influence on whether people do preventive activities is a personal recommendation from their own GP,” said Dr Oliver Frank, an Adelaide GP and clinical informatics researcher.  

“But for every person we see, there are different preventive activities that are recommended. It’s actually extremely complex, and we’re trying to do that on top of people coming to us often with half a dozen different problems to talk about,” he said. 

Previously, GPs were not made aware when a patient had been sent a testing kit. It is only recently that the National Cancer Screening Register linked to GP software to alert a GP when a patient’s screening was overdue. GPs can re-order a test kit, which may have expired, for their patient through the system if they want one, but the request is not recorded for posterity. 

“GPs’ own clinical software is very important because we can have more effective reminders,” he said. Dr Frank is currently trialling an SMS system that alerts patients that they are overdue for screening on the same day as their GP appointment and prompts them to discuss it with their doctor.  

“The challenge for us is really just to keep making sure that patients for whom it’s recommended are offered it,” he said.