Early onset colorectal cancer (EOCRC) has become the deadliest cancer for Australians under 50, being the number one cause of death in men and the third biggest in women.
Australia, along with New Zealand, now has the world’s highest rates of EOCRC, with cases rising by up to 8% annually. About one in nine new bowel cancer diagnoses occur in people under 50.
The percentage of EOCRC rose from 7.6% in 1992 to 11.1% in 2021, and Australians born in the 1990s are now three times more likely to get bowel cancer than people born in the 1950s. And younger patients are more likely to have advanced disease, with one study reporting that 81.9% of cases were Stage 3 and 4.
“The postulates for this are that it could be a different genetic disease,” says Sir Charles Gairdner Hospital’s Consultant Gastroenterologist Dr Nabil Siddique. “The mutations are slightly different in younger onset versus older onset, so that could be a reason why it’s more aggressive.
Dr Nabil Siddique, Gastroenterologist.
“But possibly the bigger thing is it presents later in younger people. Usually, younger people have, on average, symptoms present for around eight months, compared to around five months for older people. The timeframe to diagnosis is longer, usually around six months compared to two for older people. And both those things combined, and possibly the fact that it may be a slightly different genetic signature, means it tends to present later.
“So they have their symptoms for longer and the diagnosis takes longer. There are more visits to GPs before they get their diagnosis, and it does tend to be left-sided, sigmoid rectal cancers predominantly, needing more radical surgery, an increased risk of stomas, and the relapse rate is higher as well, unfortunately, in younger people. There’s a 50% chance of relapse at some point.”
This alarming upwards trend in EOCRC is putting the public health focus on earlier recognition of warning symptoms by younger adults, who might ignore changes in their bowel habits; greater awareness of the problem among GPs; and expanded access to screening.
Dr Siddique says patients in the younger age group have a “lower index of suspicion” for bowel cancer.
“Younger people are probably less likely to think they have bowel cancer or anything serious,” he says, “so they’re more likely to think it’s probably haemorrhoids or something else.
“If you ask them about rectal bleeding, and even in any other context when you’re seeing them for some other condition and you say, ‘Is there any blood in the stool?’, a lot of the time they don’t know. It’s not something they’re terribly conscious of. It might be intermittent bleeding. It may not happen very often. They don’t check their stools because they’re not worried. As whatever’s said and done, it’s still overwhelmingly an older person’s disease.”
