Bowel cancers are on the rise among under-50s in the UK, according to new studies, prompting calls to lower the screening age.
Research showed incidents of bowel cancers in adults under 50 have increased substantially over the latest available 10-year period, while the levels for other age groups either dropped or remained the same.
One study, published in the Lancet Gastroenterology and Hepatology journal, looked at colon and rectal cancer rates in developed countries such as the UK, New Zealand, Canada and Denmark.
In the most recent 10 years observed by the study – 2004-2014 – there were substantial increases, with incidents of colon cancer rising by 1.8% and rectal cancer going up by 1.4% on average each year for those in the UK.
The study showed increases among those aged 30-39 for both colon and rectal cancer.
The researchers found younger people born in the UK were now at higher risk of bowel cancer than older generations.
Across the same time period, the study found a decrease of 1.7% in incidents of rectal cancer diagnosed in those aged 75 or over.
Bowel cancer screening is currently offered on the NHS from the age of 50 in Scotland, 55 or 60 in different areas of England, 60 in Wales and 55 on the HSC in Northern Ireland. Public Health England announced last year it would be lowering the age to 50.
NHS advice suggests younger people with concerns can speak to their GP for advice.
Dr Marzieh Araghi, the lead author of the study from the International Agency for Research on Cancer in Lyon, said: “Although the incidence of colorectal cancer in adults younger than 50 years remains much 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.
“This rise in incidence among younger generations is likely to be driven in part by the changing prevalence of risk factors, such as obesity and poor diet.
“National programmes to promote healthy diets and physical activity might be the most efficient approach to ensure population-level changes.”
A second study, published in the GUT journal, found between 1990 and 2016 the number of younger people diagnosed with bowel cancer had risen at a steeper rate after 2004.
Among 20 to 29-year-olds, bowel cancer incidents rose from 0.8 to 2.3 cases per 100,000 people between 1990 and 2016.
The sharpest rise was between 2004 and 2016 at an average of 7.9% per year.
For those aged between 40 and 49, bowel cancer rates fell by 0.8% between 1990-2004 but then increased by an average of 1.6% per year from 2004 to 2016.
The authors of the study claimed several factors may be behind these trends, including the rise in obesity and lifestyle factors such as lack of physical activity, alcohol intake and smoking.
They say it is too early to use their findings to support lowering the screening age to 45 across Europe but if the trend continues screening guidelines may need to be reconsidered.
Bowel cancer is the fourth most common cancer in the UK with almost 42,000 people diagnosed every year.
More than nine out of 10 new cases (94%) are in people over the age of 50 but more than 2,500 younger people are diagnosed each year.
Around 268,000 people living in the UK today have been told they have bowel cancer, while one in 15 of all men and one in 18 women will be diagnosed during their lifetime.
Responding to the findings of the study published in Lancet, Deborah Alsina, chief executive of Bowel Cancer UK, said: “More research is needed to help us fully understand the reasons behind this increasing trend.
“In 2018, both England and Wales committed to lower the bowel cancer screening age to 50, in line with Scotland. It’s crucial that Northern Ireland also reassess their screening age.
“Screening is the best way to diagnose bowel cancer early when it is treatable and curable. Lowering this age will help to transform survival rates for bowel cancer.
Dr Andrew Beggs, consultant colorectal surgeon and Cancer Research UK advanced clinician scientist at the University of Birmingham, said: “The reasons why this is happening aren’t clear, but it must be urgently investigated.
“This means the age at which bowel cancer screening needs to start may have to change to screen people at a younger age, and people under the age of 50 with any ‘red flag’ symptoms – bleeding, a change in bowel habit, weight loss or tummy pain – should get it checked out as soon as possible.”