Artificial ingredients in takeaway meals and 'forever chemicals' found in school uniforms and frying pans may be helping drive a surge in deadly cancers among young people, a major new report warns.

British scientists also believe antibiotics could be part of the mystery behind a rise in 11 cancers among adults aged 20 to 49.

It adds to a growing global picture. In the US, early-onset cancer cases rose by almost 15 per cent between 2010 and 2019, with younger adults increasingly being diagnosed with diseases once seen mainly in older age.

The cancers include breast, bowel, thyroid, oral, endometrial, liver, kidney, gallbladder, pancreatic, womb and ovarian disease.

Many have long been tied to the global obesity crisis.

But experts from The Institute of Cancer Research and Imperial College London said weight gain alone cannot explain the sharp rise in younger adults.

Instead, they believe ultra-processed foods – known as UPFs – may be one cause. They added that PFAS – so-called 'forever chemicals' used in cookware, clothing and household products – could also be to blame.

Experts are now calling for urgent research into what is driving cancer in younger people – while warning policymakers must also tackle the obesity epidemic already fuelling many early-age cases.

'Whilst BMI [weight] remains our best clue as to why cancer is on the rise in this age group, much of the increase still remains unexplained,' said Professor Montserrat García-Closas, of The Institute of Cancer Research in London.

'This tells us that multiple factors – including early-life exposures – may be acting together. Understanding these patterns is essential if we are to identify what is truly driving cancer risk in today's generation.

'However, we cannot wait to act. It's crucial that we act now on what we already know: tackling obesity across all ages could slow the rise in cancers and must become a national priority.'

In the study, published in BMJ Oncology, researchers examined incidence trends across more than 20 cancers in England between 2001 and 2019, before comparing the findings with the latest diagnosis data from 2023.

They found 11 cancers are now rising among adults aged 20 to 49.

In 2023 alone, around 31,000 younger adults were diagnosed with cancer, with women accounting for almost two-thirds of cases – largely because of breast cancer.

The cancers identified were breast, bowel, thyroid, oral, endometrial, liver, kidney, gallbladder, pancreatic, womb and ovarian cancer.

All but one of the 11 – oral cancer being the exception – have long been associated with obesity, reinforcing concerns over Britain's growing weight crisis.

The rise in oral cancer, meanwhile, remains more puzzling. Rates have climbed by 26 per cent across England in the past decade.

Among younger adults, cases have jumped by more than 13 per cent over the same period. Some experts believe falling HPV vaccination uptake may be one factor.

Smoking, alcohol and lack of exercise are also known to raise cancer risk.

But researchers said, aside from obesity, many of these classic risk factors are actually becoming less common.

Young adults today, for example, are far less likely to smoke or drink heavily than they were two decades ago.

That has led scientists to suspect more modern exposures may also be playing a role.

One possible culprit is ultra-processed food, or UPFs, which studies suggest now make up around half of the average UK diet.

They are commonly found in ready meals, breakfast cereals, protein bars, fizzy drinks and fast food.

Previous research has linked UPF-heavy diets to cancer. Earlier this year, one major study found people who regularly eat them were more likely to develop pre-cancerous bowel growths.

Another suspect is PFAS, so-called 'forever chemicals' used in everything from non-stick pans to waterproof clothing and food packaging.

Last week, MPs on the Environmental Audit Committee urged ministers to curb their use after warnings they can build up in the body and environment for decades.

Antibiotics have also come under scrutiny.

Experts note use of the bacteria-fighting drugs surged in the 1970s, after the success of penicillin led to a widespread belief medicine had effectively conquered infectious disease. At the time, far less was known about the long-term consequences of repeated use.

Scientists believe UPFs, PFAS and antibiotics may all disrupt the gut microbiome – the trillions of bacteria in the digestive system that play a crucial role in health. Disturbing that balance may trigger changes linked to cancer.

'The changes we're seeing in cancer incidence, particularly the rates of some cancers in younger adults, don't have a single cause or simple answer,' said Professor Marc Gunter, co-director of the Cancer Epidemiology and Prevention Research Unit at Imperial College London.

'But it is possible that changes in the gut microbiome – potentially caused by ultra-processed foods, forever chemicals and an increase in antibiotic use in the 70s – could explain some of the changes in cancer rates.'

Professor García-Closas added: 'Cancer is a very complex disease, so there are very few examples where one single factor drives the majority of cases, like smoking and lung cancer.

'While obesity is an important factor, there is still a lot we don't know and it is dangerous to pinpoint single suspicious factors.'