The study, titled “Global burden of cancer attributable to high body-mass index in 2012: a population-based study”, and published in The Lancet Oncology, estimated that a quarter of all obesity-related cancers in 2012 may be the result of the increasing average body mass index (BMI) since 1982.
“We found that about 3.6 per cent of the cancers worldwide – or nearly half a million new cancer cases a year – were caused by excess body weight,” study author Dr. Nirmala Pandeya said in a university news release. “In Australia, the percentage is similar, with 3.4 per cent of all cancers in men (2350 new cases) and 7.4 per cent (3782 new cases) in women diagnosed in 2012 attributable to overweight and obesity.”
Previous studies had already demonstrated that obesity was tightly linked with an increased risk of developing colorectal cancer.
The research team designed a population-based study to derive population attributable fractions (PAFs) using relative risks and BMI estimates in adults by age, sex, and country.
They then calculated PAFs using BMI estimates from 2002 and used data from GLOBOCAN 2012 database to assess new cancer cases derived from high BMI.
“Of these cancers, we found that, for men, 23 per cent of kidney cancers, 19 per cent of colon cancer and 13 per cent of pancreatic cancer could be attributed to excess weight”, said Dr. Pandeya, further explaining that this impact was more prominent in women. “Post-menopausal breast cancer and endometrial cancer were responsible for more than 60 per cent of cancers due to obesity in women diagnosed in Australia in 2012. That’s more than 2000 cases”, she added.
The results from the study also showed that cancer numbers were higher in the developed world, especially in the U.S., stressing the necessity of increased efforts to fight the frequency of overweight and obesity.
“Other important risk factors for cancer, such as smoking, are declining, but we see the proportion of overweight and obese men and women still rising in most countries. If this trend continues we are likely to see an increasing number of people diagnosed with cancers that could have been avoided by maintaining a healthy weight”, Dr. Pandeya concluded