Being obese has been strongly linked to 11 different cancers, according to a large-scale study.
The research, published in the British Medical Journal (BMJ), found that being obese increases the risk of cancer of the oesophagus, multiple myeloma, stomach, bowel, rectum, biliary tract system (liver, gall bladder and bile duct), pancreas, postmenopausal breast, womb, ovary and kidney.
Authors revealed that there may be links between obesity and other cancers, but existing studies did not provide a strong enough link.
Researchers conducted a comprehensive review of a range of studies on the topic of obesity and cancer risk, according to The Press Association.
The team, led by Maria Kyrgiou and Kostas Tsilidis from Imperial College London, identified 204 studies that analysed at the link between body mass index (BMI), weight gain, and waist circumference, and 36 cancers and their subtypes.
However only a handful were deemed to be “supported by strong evidence”.
Cancer is a leading cause of death worldwide and obesity has more than doubled globally over the past 40 years.
The World Cancer Research Fund (WCRF), which funded the study, estimates that around 25,000 cancer cases could be prevented in the UK every year if everyone was a healthy weight.
The WCRF has previously identified most of the cancers as being linked to obesity, although multiple myeloma is a new one on the list.
Dr Panagiota Mitrou, director of research funding at WCRF, said: “This research, which we have funded, further emphasises the huge role that obesity plays in increasing cancer risk.
“After not smoking, being a healthy weight is the most important thing people can do to reduce their cancer risk.
“With obesity rates continuing to rise in the UK and worldwide, it is incredibly important that tackling the obesity epidemic be made an urgent priority.”
The Obesity Health Alliance, a coalition of over 35 health charities, campaign groups and Royal Medical Colleges, said: “Obesity is a serious health concern and on top of being linked to major cancers, can also increase the risk of Type 2 diabetes, heart and liver disease and mental health problems.
“With over a quarter of adults obese, and nearly one in three children overweight or obese by the time they leave primary school, we need bold action to help us all make healthier choices.
“This is why it’s so important to introduce measures like the soft drinks industry levy, reduce sugar, saturated fat and salt from everyday foods, and close loopholes to protect children from junk food marketing.”
Dr Alison Tedstone, chief nutritionist at Public Health England, said: “While this research provides yet more evidence of the link between obesity and some major types of cancer, more people need to be aware of the risk.
“Less than half the population realise that being obese increases the risk of cancer and, with almost two-thirds of adults carrying excess weight, this is worrying.
“Through our Change4Life and OneYou campaigns, we’re helping families understand the risk of being overweight and obese, but also sharing tips, advice and information on what they can do to try and avoid it.”
In a linked editorial, Yikyung Park and Graham Colditz from Washington University School of Medicine explain that “though some specifics remain to be worked out, the unavoidable conclusion from these data is that preventing excess adult weight gain can reduce the risk of cancer.”