'Strong evidence' links obesity and some major cancers - study

A new study has found that obesity is strongly linked to 11 different cancers including that of the digestive organs and hormone-related malignancies.

According to the study which was published in the British Medical Journal (BMJ), being obese increases the risk of multiple myeloma and cancer of the oesophagus, stomach, bowel, rectum, biliary tract system (liver, gall bladder and bile duct), pancreas, postmenopausal breast, womb, ovary and kidney.

The research which was carried out by a team of international researchers, funded by the World Cancer Research Fund (WCRF) and led by Maria Kyrgiou and Kostas Tsilidis from Imperial College London, looked at data from 204 meta-analyses that looked at the link between body mass index, weight gain, and waist circumference, and 36 cancers and their sub-types, which each combine the evidence from several individual studies using a new statistical technique called an "umbrella review", they were able to assess which cancers had the strongest associations with obesity, but only a few studies were supported by strong evidence.

The researchers found there to be "substantial uncertainty" regarding the associations between obesity and another 25 types of cancer. They acknowledged that there could be a valid association with those cancers too, but further study is required.

"Obesity is strongly related with a significant number of cancers, and there is no doubt this is the case," said the study's first author, Maria Kyrgiou.

"The main message is we have the evidence. We have to realize the moment an obese patient walks into our clinic, this is a patient who's at high risk," she said. It's hoped that doctors will be able to target personalized cancer prevention strategies to those individuals.

Being overweight could increase the risk of a host of cancers, including those of the colon, breast, pancreas and ovary, researchers warned.

The WCRF has previously identified most of the cancers as being linked to obesity, although multiple myeloma is new on the list.

"This research, which we have funded, further emphasises the huge role that obesity plays in increasing cancer risk," said Dr Panagiota Mitrou, the director of research funding at WCRF.

"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."

And according to the Obesity Health Alliance, a coalition of more than 35 health charities, campaign groups and Royal Medical Colleges, 

"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.

"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."

Press Association