Should bowel cancer screening be reimagined?

If they catch it early, more than 95% of people survive a diagnosis of bowel cancer – but prognosis gets much worse at later stages.

While there’s a free, simple screening test for people at higher risk, fewer than half of Australians do it when it’s mailed to them.

What’s more, while people aged over 50 are most at risk, younger people are getting bowel cancer at inexplicably rising rates. This increase has led to countries like the US dropping the screening age from 50 to 45.

“I’m hoping we’ll see a similar change in Australia,” says Associate Professor Erin Symonds, from Flinders University’s College of Medicine and Public Health. But that’s not the only way she hopes the screening will change in Australia.

The screening test – the “poo test” – is mailed to people in Australia between 50 and 74 years old every 2 years.

People have to collect tiny samples of their poo, which are then sent back for a “faecal occult blood test”. This test doesn’t check for bowel cancer specifically: instead, it looks for small amounts of blood, which can be caused by bowel cancer.

“All of these people need a colonoscopy once they have a positive test result,” says Symonds.

This allows clinicians to spot bowel cancer as early as possible – in fact, catch it while it’s still precancerous – but much like the poo test, it’s not an attractive procedure. Particularly if it turns out to have been unnecessary.

“When interviewed after having that colonoscopy, some people feel reassurance that there was nothing there, but some people feel disappointed that they went through the extra procedure for no reason,” says Symonds.

Plus, there’s a long wait time for colonoscopies – the median wait time in Australia is 82 days after a positive poo test, with a range of 28-435 days.

What are the alternatives?

Symonds and colleagues are working on blood tests for bowel cancer. These blood tests pick up tiny hints of cancer DNA in a person’s blood, or other biomarkers. They can be more specific than the poo test, and give a much better sense of whether a colonoscopy is needed.

The researchers are particularly interested in blood tests for higher risk groups – people with gastrointestinal symptoms, and bowel cancer survivors. But the idea is attractive for plenty of other people too.

“When we give people the option of a poo test or a blood test, three quarters say ‘I’ll do a blood test!’,” says Symonds.

What are the downsides? Not everyone gets blood tests done when asked to either – they might be frightened by needles, or just not have the motivation or means to get to a pathology clinic. Plus, the results it yields are different.

“The poo test can be done at home, and it can pick up things as early as possible. With blood tests, you have to go somewhere, it has to go through a special lab, and is going to be good at picking up the cancers but maybe not picking up the pre-cancers so much,” says Symonds.

While all of these options are free for patients in Australia, there are additional costs for taxpayers.

“Blood tests to look for these biomarkers are going to cost at least triple what the simple poo test costs,” says Symonds.

The poo test is cheap for the government, about $30 per test, according to Symonds. Some blood biomarker tests can be upwards of $5,000.

“That is not something that can be rolled out to the general public,” says Symonds.

So for now, our “best option” for screening remains the poo test.

“With improving technologies, I’m hoping we’ll see a more affordable blood test to get people those options,” says Symonds.

And if you’ve received a bowel cancer test in the mail, she urges you to take it and send it back – it might be an awkward few minutes, but it could save your life.

Associate Professor Erin Symonds joined Cosmos on stage at Science City on the topic of Cancer. You can find out more and watch the full event here.

Correction, 30 January 2024: An earlier version of this article stated incorrectly that bowel cancer screening tests are free for Australians aged 50 to 75. The correct age range for screening in Australia is 50 to 74. We have updated the article.