Obesity could be fuelling four in ten cases of cancer, a landmark study has revealed.
The stark roll it plays in the deadly disease is even greater than feared, according to research involving 4.1million adults.
Experts said obesity is now linked to more than 30 types of cancer – an increase from the 13 in which it is known to play a role.
They warned the ‘groundbreaking’ research which spanned four decades, shows the nation faces a devastating timebomb.
It found for every five-point increase in body mass index (BMI) – equivalent to gaining about three stone for someone who is a healthy weight – increased the chances of getting several common cancers by 24 per cent in men and 12 per cent in women.
The same increase was linked to 19 other cancers, raising the risk by 17 per cent for men and 13 per cent for women.
Health charities said it should serve as a ‘wake-up call’ to ministers and called for restrictions on junk food advertisements to tackle Britain’s obesity epidemic.
Katharine Jenner, Director of the Obesity Health Alliance, said: ‘The results are clear – if we can prevent obesity, we can prevent many types of diet-related cancers.
‘This should be a wakeup call to the UK Government/governments around the world, to urgently implement public health policies which will make a meaningful difference, such as restrictions on junk food marketing, and levies on unhealthy food.
‘We need to make the healthy choice the easy choice for everyone.’
Scientists believe obesity may increase cancer risks through biological mechanisms such as chronic inflammation, alterations in metabolism, and changes in hormone levels.
Reduced participation in cancer screening programs and decreased efficacy of screening procedures in people living with obesity may also be factors.
The study led by Lund University in Malmo, Sweden, involved 4.1million people with monitored weight and lifestyle for about 40 years.
Some 332,500 cancers were identified during this time and of these, there appeared to be a link between excess weight and cancer in 40 per cent of cases.
Researchers examined 122 types and subtypes of cancer in a study which tracked patients over a follow-up period of more than 100 million years.
In total, researchers identified 32 types of cancer with an obesity link, more than double the 13 types of cancer identified by the International Agency for Research on Cancer in 2016.
The new research, which will be presented at the European Congress on Obesity in Venice, confirms these cancers – including breast, bowel, womb and kidney – can be caused by obesity.
A further 19 potential obesity related cancers were also identified for the first time, including malignant melanoma, gastric tumours, cancers of the small intestine and pituitary glands, as well as types of head and neck cancer, vulval and penis cancer.
Some four in 10 cases of cancer could be fuelled by obesity overall, the research suggests.
Lead researcher, Dr Ming Sun, said: ‘Our findings suggest that the impact of obesity on cancer might be greater than previously known, in that it is a risk factor for more cancers, especially of rarer kind.
‘Some of these have rarely or never before been investigated in relation to obesity.’
She added: ‘Implementing public health measures enabling and advocating a healthy lifestyle are essential to address the obesity epidemic and its already known detrimental effect on health outcomes.’
According to the most recent NHS health survey in England, 26 per cent of adults are obese and a further 38 per cent are overweight, at a cost of around £6.5billion a year.
Dr Jennifer Baker, co-chair of the Childhood Obesity Working Group for the European Association for the Study of Obesity, said given 60 per cent of adults in Europe are obese or living with pre-obesity, ‘we are likely facing a significant increase in cancer cases’.
One million patients, who were a healthy weight with a body mass index (BMI) of 18 to 25, were calculated to cost the NHS an average of £638 each in 2019, the final year of the study. By comparison, severely obese patients with a BMI of 40 and above cost more than double – at £1,375 annually. Meanwhile, the NHS spent £979 a year on obese patients with a BMI of 30 to 35, which increased to £1,178 a year for those with a BMI of 35-40
Describing it as a ‘groundbreaking study’, she said: ‘Researchers show that obesity is associated with 19 new cancer forms, some of which are surprising, in addition to the 13 that have already been identified.
‘Given that we are likely underestimating the burden of cancer attributable to obesity, these results show that greater attention should be given to obesity in cancer prevention programs.’
Professor Jason Halford, President of the European Association for the Study of Obesity, said: ‘This is a really strong large-scale analysis.
‘As always, more research is needed but it reveals what many studying the links between cancer and obesity have suspected; that obesity is likely to be a risk factor for many more types of cancer than we had evidence for before.
‘If this does not cause concern for health policy makers it is difficult to see what will.’
The Health Secretary said the major conditions strategy will set out the government’s approach to addressing lifestyle drivers of ill-health and disease, such as diet and obesity and pointed to successes such as the sugar reduction programme.
Victoria Atkins said: ‘I want us all to be able to lead longer, healthier lives. That starts with preventing illness through healthy lifestyle choices, like eating well, exercising regularly and not smoking.
‘We are already introducing world-leading legislation to protect future generations from the harmful effects of smoking to reduce illnesses like cancer, and we’re taking strong action to tackle obesity too.
‘By investing in tech like the NHS Couch to 5k app, we are helping families all over the country get fit and active, and I am excited about the new treatments and technologies that can help people achieve – and maintain – a healthy weight.’
WHAT SHOULD A BALANCED DIET LOOK LIKE?
Meals should be based on potatoes, bread, rice, pasta or other starchy carbohydrates, ideally wholegrain, according to the NHS
• Eat at least 5 portions of a variety of fruit and vegetables every day. All fresh, frozen, dried and canned fruit and vegetables count
• Base meals on potatoes, bread, rice, pasta or other starchy carbohydrates, ideally wholegrain
• 30 grams of fibre a day: This is the same as eating all of the following: 5 portions of fruit and vegetables, 2 whole-wheat cereal biscuits, 2 thick slices of wholemeal bread and large baked potato with the skin on
• Have some dairy or dairy alternatives (such as soya drinks) choosing lower fat and lower sugar options
• Eat some beans, pulses, fish, eggs, meat and other proteins (including 2 portions of fish every week, one of which should be oily)
• Choose unsaturated oils and spreads and consuming in small amounts
• Drink 6-8 cups/glasses of water a day
• Adults should have less than 6g of salt and 20g of saturated fat for women or 30g for men a day
Source: NHS Eatwell Guide
