Scientists have issued a warning that common everyday foods are causing a surge in cancer cases in under-50s.
Ultra-processed foods including bread, breakfast cereal and crisps are a major factor contributing to cancer diagnosis rates among young people rising by a quarter in two decades.
About 35,000 under-50s a year are being diagnosed with rising numbers of cancers commonly seen in older people, such as bowel, breast and stomach.
Scientists say the trend is linked to people eating too much ultra-processed food with research presented at the world’s biggest cancer forum saying rising cases of bowel cancer may have an association with changes to the gut microbiome reducing the body’s ability to deal with pre-cancerous cells.
Professor Charles Swanton, Cancer Research UK’s chief clinician, says cancer remains most prevalent in older people but is alarmed by its rise in young people.
At the American Society of Clinical Oncology’s annual meeting he said: “Over recent decades, there has been a clear increase in cancer incidence rates in young adults in the UK.
“We don’t have a good answer as to why this is happening.”
The incidence rate of “early onset” cases grew from 132.9 per 100,000 people in 1995 to 164.6 in 2019, according to analysis by Cancer Research UK.
The overall incidence rate across all ages has increased by 13 percent from 539 per 100,000 people to 611.5.
Research by Ohio State University presented at the Chicago meeting found that under-50s with bowel cancer had cells that appeared to be 15 years older than their real age.
It suggests Western diets are impacting the balance of bacteria and inflammation in the gut, which can cause “accelerated ageing” in the colon.
A bacteria called fusobacterium, linked to diets low in fibre but high in sugar, was found to increase inflammation in the gut, in turn raising the risk of cancer.
The findings add to growing evidence illness and disease can occur through changes to the microbiome as well as damage from long-term swelling.
Mr Swanson said: “In some instances, there are maybe associations emerging that distinct microbial species may be associated with early onset cancer risk.
“What we are seeing in some studies is some tumours from patients with early onset colorectal cancer harbour mutations that might be initiated by these microbial species.
“Suggesting that potentially some of these microbes might initiate mutations in DNA. This is not dissimilar from the way that tobacco smoke induces mutations in lung lining cells.’”