Experts have called for the bowel cancer screening age to be lowered after a rise in the number of cases among the under-50s.
Soaring obesity and poor diet are being blamed for the worrying hike. But the levels for other age groups either dropped or remained the same.
A 10-year study showed colon cases in the under-50s rose by 1.8% and rectal cancer by 1.4% a year on average. There were increases among those aged 30-39.
More than 2,500 younger people are now annually diagnosed with the disease, that kills 16,384 Brits a year.
NHS screening is offered from age 55 or 60 in England and 60 in Wales. Public Health England said last year it would lower that to 50.
Study lead author Dr Marzieh Araghi from the International Agency for Research on Cancer in Lyon said: “Although the incidence of colorectal cancer in adults under 50 years remains lower compared with that in older age groups, our findings are of concern and highlight the need for action to counteract the rising burden of the disease in younger people.”
Bowel Cancer UK chief executive Deborah Alsina added: “More research is needed to help us understand the reasons behind this increasing trend Screening is the best way to diagnose bowel cancer early when it is treatable and curable. Lowering the screening age will help to transform survival rates.
“The time has passed where it is in any way acceptable to tell someone under 50 they are too young for bowel cancer.
“Two years ago we published a risk assessment tool to support GPs in deciding who to refer for diagnostic testing. Yet the NHS has so far failed to implement this, or to clarify the best first-line test for younger patients.”
Deborah James, a deputy head teacher in London, has written about her life with the disease in her podcast You, Me and the Big C.
She said: “When I look back at old pictures, I wish I had known the symptoms.
“My point being in all the pictures I look healthy but I was pooing blood, was tired and had a change in bowel habits.”
BBC Middle East editor Jeremy Bowen this year revealed he has bowel cancer.
The study, published in the Lancet Gastroenterology and Hepatology journal, showed a decrease of 1.7% in rectal cancer among the over-75s.