Cancer doctors have warned of a rise in aggressive colon cancer among teenagers – amid rising diagnoses in the under 50s.
Researchers from the US said the disease is ‘unfortunately, becoming more common in adolescents’ and added that it is often a more deadly form than the type seen in older adults.
In a study of patients aged 21 and under at 34 US hospitals, the researchers found that 45 per cent died and 37 per cent saw their cancer return within a year.
The average survival rate for bowel cancer in the UK is around 60 per cent across all age groups.
Now, the doctors behind the study, from Mass General Brigham Cancer Institute, have urged fellow medics to look for less-obvious signs of the disease in younger people.
Nearly three-quarters of the patients in the study suffered back or abdominal pain, making it the most common symptom experienced by adolescents.
Other symptoms included rectal bleeding, changes in bowel habits and weight loss – although these signs were less common.
Experts say the combination of especially aggressive disease and delayed diagnosis due to less obvious symptoms is responsible for a tragically high fatality rate.
Rates of colorectal cancer – which include cancers that start in the colon or the rectum – have surged exclusively in under-50s over the past two decades.
Experts have previously blamed the rise on poor diets, sedentary lifestyles and increasing obesity rates.
‘Colorectal cancer is, unfortunately, becoming more common in adolescents and young adults and represents a different disease than colorectal cancer diagnosed in older adults,’ Dr Erica Arnold, a pediatric surgeon and study lead author, said.
‘When diagnosed, it is often aggressive and associated with high rates of relapse and mortality.’
The new findings were presented at the annual meeting of the American Academy of Pediatrics, which focused on colorectal cancers in patients 21 and under.
The study involved 84 patients, who were diagnosed with the disease between 2012- 2023 at 34 hospitals.
Patients who were already known to be at high risk of bowel cancer – for example those with inflammatory bowel disease – were excluded.
The average age at diagnosis was 16.5 and one in five patients had a parent, sibling or grandparent with colorectal cancer.
Back or abdominal pain was reported by 74 per cent of patients, while just under half (45 per cent) experienced a change in bowel habits.
Around 40 per cent of patients reported unexplained weight loss prior to diagnosis, and just over a third (38 per cent) experienced rectal bleeding.
The majority of patients presented with advanced disease – meaning the cancer had already spread to nearby lymph nodes or other parts of the body, such as the liver and lungs.
Dr Arnold concluded: ‘Children and adolescents without known colorectal risk factors experience delays in diagnosis and the majority do not have a known family history.’
She added that, with cases rising in young people, doctors should consider bowel cancer as a possible cause of telltale symptoms, even in those without known risk factors.
The NHS lists changes in bowel habits, needing to go more or less frequently than usual, blood in the stool and rectal bleeding as the main signs of the disease.
Unexplained weight loss, abdominal pain and fatigue also feature as possible warning signs.
The updated guidance comes following a major study which found that obesity is a key factor for the rising rates of cancer among young people in England.
There are now 11 types of cancer, including bowel, that are increasing among people aged 20 to 49, according to Imperial College London analysis.
Obesity is the only known behavioural risk factor that has been increasing in younger adults over the past two decades – with more than a third of British teenagers now classed overweight or obese – while more established risk factors such as smoking and alcohol have declined.
Researchers also pointed to ultra-processed foods, ‘forever chemicals’ and antibiotics as potential contributors to the rise in deadly cancers among young people.
However, much of the increase still remains unexplained.
