Belly fat may increase cancer risk: WHO study

People with an expanding waistline may be at a greater risk of developing certain cancers, including bowel, breast and pancreatic, a new WHO study warned today.

Waist measurement is as good at predicting cancer risk as body mass index (BMI), which is a ratio of weight to height, said researchers from International Agency for Research on Cancer (IARC-WHO), the specialised cancer agency of the World Health Organisation (WHO).

They found that that adding about 11 centimetres (cm) to the waistline increased the risk of obesity related cancers by 13 per cent. For bowel cancer, adding around 8 cm to the hips is linked to an increased risk of 15 per cent, researchers said.

Being overweight or obese is the single biggest preventable cause of cancer after smoking and is linked to 13 types of cancer including bowel, breast, and pancreatic, researchers said.

Carrying excess body fat can change the levels of sex hormones, such as oestrogen and testosterone, can cause levels of insulin to rise, and lead to inflammation, all of which are factors that have been associated with increased cancer risk, they said.

Using a novel approach, researchers showed that three different measurements of body size, BMI, waist circumference, and waist to hip ratio all predicted similar obesity-related cancer risk in older adults.

They combined data from around 43,000 participants who had been followed for an average of 12 years and more than 1,600 people were diagnosed with an obesity-related cancer.

"Our findings show that both BMI and where body fat is carried on the body can be good indicators of obesity-related cancer risk," said Heinz Freisling, from IARC-WHO, "Specifically, fat carried around the waist may be important for certain cancers, but requires further investigation".

The study was published in the British Journal of Cancer.