The death of American actor James Van Der Beek has brought renewed attention to the sharp increase in colorectal cancer cases among those under 50 in recent years. The causes, still unknown, are the subject of much research.
The star of the hit late 1990s and early 2000s series "Dawson's Creek" died last week at the age of 48 from colorectal cancer, which affects the colon and rectum.
In 2020, his compatriot Chadwick Boseman, made famous by "Black Panther", was taken by the same disease at the age of 43.
People born in the 1990s have a four times higher risk of developing colorectal cancer than those born in the 1960s, according to a study published last year in the Journal of the National Cancer Institute, whose data came from Australia, Canada, the United Kingdom and the United States.
It is now the leading cause of cancer death among people under 50 in the United States, according to a study published last month in the journal JAMA. "It's really frightening," emphasized Helen Coleman, a professor of oncology at Queen's University Belfast, "but we were starting from a very low level."
However, the vast majority of cases involve older people: only 61% of colorectal cancers are diagnosed in those under 50, according to his research, conducted in Northern Ireland.
In addition, rates are stabilizing, or even decreasing, among the elderly in some regions thanks to improved screening, she added.
But, less inclined to think that they could be affected by this cancer, young people are unfortunately often diagnosed too late, as was the case for Van Der Beek.
– What is the cause of this increase? –
Like other cancers affecting young people, colorectal cancer has been associated with being overweight and having an unhealthy lifestyle: poor diet, lack of physical exercise, alcohol consumption, smoking.
But these factors alone do not explain "the considerable increase observed in a relatively short period of time," says Ms. Coleman.
Especially since many young patients with colorectal cancer had a good lifestyle, like Van Der Beek, diagnosed in 2023.
"I was going to the sauna, taking cold baths, etc. – and I had stage 3 cancer without knowing it," the father of six revealed in December.
What could explain this relatively sudden increase?
"We don't know," Jenny Seligmann, a colorectal cancer researcher at the University of Leeds, UK, told AFP.
This mystery has led researchers to explore other avenues, including that of the microbiota, this vast ecosystem of microbes, still poorly understood, which populates our intestine.
A study published last year in the journal Nature highlighted a "very important first clue," said Ms. Coleman.
– Screening before age 50 –
She revealed that mutations in the DNA of a genotoxin—a weapon used by bacteria to protect themselves from other microbes—called colibactin, produced by the bacterium Escherichia coli, were much more common in young people with colorectal cancer than in older patients. But this finding needs to be supported by further research.
Other research suggests that repeated use of antibiotics may be associated with early colorectal cancer.
Ms. Seligmann also indicated that she observes numerous subtypes of colorectal cancer, suggesting that the causes are diverse. "It will be very difficult to identify just one," she believes.
Before his death, a gaunt Van Der Beek urged anyone with even the slightest symptom to get tested. "I want to shout it from the rooftops: if you are 45 or older, see your doctor!"
Diarrhea, constipation, but also the presence of blood in the stool, unexplained weight loss and fatigue, should raise concern.
Faced with this increase in the number of cases among young people, the United States lowered the age at which screening begins in 2021, from 50 to 45 years old.
Calls are growing for other countries to follow this example: the United Kingdom and France already offer screening from the age of 50.
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