The most significant risk factor for cancer is one none of us has any control over: increasing age. In Australia, those aged 60 and older comprise less than a quarter of the population, but account for nearly three-quarters of new cancer cases.
But in recent decades, the rates of some cancers have risen in younger Australians, prompting calls to widen the age eligibility for national screening programs.
Australia has three nationwide cancer screening programs: the cervical screening program for people aged 25 to 74; BreastScreen Australia, which invites women between 50 and 74 to have regular mammograms; and the bowel cancer screening program, which provides free test kits in the mail to test for blood traces in the stool of people also aged 50 to 74.
Rates of bowel cancer – also known as colon, rectal or colorectal cancer – have risen sharply in Australians under 50, disproportionate to population growth. Between 2001 and 2021, the incidence of bowel cancer in people aged 20 and 39 more than doubled, from 4.4 cases per 100,000 people to 10.3 cases.
Epidemiologists have seen increasing rates in young people in countries including the UK, US, Canada and New Zealand, while bowel cancer rates in older populations are dropping or remain stable. Organisations such as Bowel Cancer Australia have thus been lobbying for the national screening age to be lowered from 50 to 40, or at least to 45, in keeping with US guidelines.
“Of the nearly 16,000 bowel cancers in Australia each year, one in 10 is now in somebody under 50,” says the organisation’s medical director, Graham Newstead, an associate professor and retired colorectal surgeon. “We’re not screening for them.
“The public is not aware of the risk … and GPs are not always aware of the risk in young people.”
Compared with older people, young-onset bowel cancer patients are more likely to be diagnosed at a later stage (stage III or IV cancer). If someone receives a positive result for traces of blood in their stool, they should be referred to have a colonoscopy within 120 days.
A national bowel cancer screening program monitoring report, published last October, found that in 2020 the national median wait time between someone testing positive on the faecal occult blood (FOB) test and having a colonoscopy was 49 days – with only 53.9% of people having the procedure within 120 days.
That waiting period can vary widely depending on state and location, with a discrepancy between the public and private health systems (median wait times of 77 days and 44 days respectively).
In 2019, Anthony Ellison, then 39, was told that he would have to wait five months for a colonoscopy in the public system. The Newcastle-based personal trainer had an elective colonoscopy privately within a month and was diagnosed with stage IV bowel cancer that had spread to his liver.
Ellison began chemotherapy a month before the date of his originally booked colonoscopy. “I probably wouldn’t be here still, to be honest, if I had to wait another five months,” he says.
Anecdotally, the pandemic has also resulted in long delays. “We’re now seeing people who were without symptoms, with a positive result in 2021, long delayed in getting colonoscopies [who] now have incurable disease,” Newstead says.
Some have expressed concerns that lowering the age cutoff for bowel cancer screening could inflate colonoscopy wait times, negating the advantage of early detection through FOB testing.
A key consideration is whether Australia has the financial capacity and manpower to handle increases in FOB-positive patients requiring a colonoscopy if the screening cutoff is lowered to 45, says Savio Barreto, an associate professor in medicine at Flinders University.
Decisions about publicly funding a medication or health program are often made on the basis of what is known as the “willingness-to-pay threshold”; a measure is deemed cost-effective if it costs less than $50,000 per life year saved.
A 2018 study estimated that lowering the national bowel cancer screening program to begin at 45 met this threshold, costing between $17,053 and $29,512 per life year saved compared with between $2,984 and $5,981 for the current 50-74 program.
Starting screening at 45 would increase colonoscopy demand by 3% to 14%, it also found, with 55 to 170 additional colonoscopies required to prevent each additional death.
Of those already eligible for screening, only 40.9% of people returned samples in 2020-21, prompting a push from the federal health minister in June to increase participation rates.
“Can we target the screening so that we get higher yield?” Barreto says, pointing to a 2022 paper which found lowering the screening age to 40 for First Nations people would reduce bowel cancer incidence and mortality. “That is where we may have greater benefit in terms of dropping the age.”
Dropping the screening age “is a no-brainer, as far as I’m concerned”, Newstead says.
“The mortality rate is much higher [in under-50s] than the comparative mortality rate in the older group.”
• The subheading of this article was amended on 4 August 2023. An earlier version said that cancer rates for patients under 50 “are now one in 10”; as the article makes clear, the one in 10 figure relates to the proportion of total bowel cancer diagnoses that are now in people under 50.
