2 November 2023
Bowel screening should start at 45, says NHMRC
The NHMRC has released updated guidelines recommending that Australians with average risk be invited to screen every two years through the National Bowel Cancer Screening Program from the age of 45, rather than 50, and be able to request screening from their primary care provider from the age of 40.
The guidelines have been developed by the Cancer Council Australia and approved by the NHMRC.
The earlier starting age, which brings us in line with US guidelines, has been hotly debated here, with some saying the evidence isn’t there to justify it. Even the guideline recommendation summary notes that the evidence is “weak”.
However, research clearly shows that bowel cancer rates in younger people have been climbing for 30 years, with one in nine diagnoses (1,716 per year) occurring in those under 50. People in their 40s account for 56% of new cases and 64% of deaths under 50.
Focussing 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, terminal prognosis.”
There are few randomised control trials of bowel screening programs, said Mr Wiggins. “Crafting guidelines in that sort of vacuum of evidence isn’t the easiest of things to accomplish.”
This lack of Grade A evidence is 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 are similar, they noted.
“You can see rising rates, it’s been well researched and reported over 30 years, but then no one’s actually done any research as to what a screening program would potentially look like in that age category,” said Mr Wiggins.
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 doesn’t reflect the total number of people taking some action, other than sending the test kit back 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.”
With the change in start date, the overall participation number might seem to go down further because the pool of participants was being increased by potentially 1.6 million, but the important thing was the overall effect, he said.
“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.
Another hurdle to change has been the issue of cost.
“At present, the NBCSP continues to send bowel screening kits to eligible Australians aged 50 to 74. Any changes to the NBCSP following updates to the guidelines requires Australian Government consideration,” said a spokesperson for the National Bowel Cancer Screening Program.
Meanwhile, the Department of Health and Aged Care said in a statement that they are “carefully considering the implications of the recommendation in the updated Guidelines to lower the eligible age of the NBCSP to 45 years, including the costs and flow on implications for the broader health system”.
A 2021 review of the program by Deloitte found that 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 avoided), but less cost-effective from a healthcare system perspective ($9936 per DALY avoided).”
“[T]here 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.”
Implementation of the program is a factor which particularly affects GPs.
“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 specialist GP Dr Oliver Frank, who practises in the north-east suburbs of Adelaide and has been researching clinical informatics for many years.
“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.
Up until recently, 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 goes out to patients on the day of their GP appointment, telling them they are overdue for screening and to discuss it during their visit.
“The challenge for us is really just to keep making sure that patients for whom it’s recommended are offered it,” he said.