Media release from Science Media Centre

Research published in The Lancet Oncology today shows a strong causal link between obesity in Asia-Pacific people, and an increased risk of dying from cancer.

While an increased risk of death from cancer has been linked with obesity in Western populations, little research until now has looked at any effects in Asia-Pacific populations.

Now, a study of Asia-Pacific people, including 10,400 New Zealanders, has found that overweight and obese people are 6% and 21% (respectively) more likely to die from cancer when compared with their normal-weight counterparts.

The Lancet paper can be accessed by registered journalists in the SMC Resource Library. The SMC rounded up comment on the paper from obesity and nutrition experts:

Dr Elaine Rush, Professor of Nutrition, Faculty of Health and Environmental Science, Auckland University of Technology comments:
"The Asia Pacific Cohort Studies collaboration of almost half a million people in the Asia Pacific region included 10,400 New Zealand people first measured in 1992. The important message to take from this study is that in general an increase in body weight (forget BMI - adults do not change in height) is associated with increased risk of cancer (in general).

"The use of BMI cut-offs is a tool to look at patterns of association - it does not mean for an individual that if BMI is normal that there is necessarily less personal risk of cancer. We do not know! The increase in body weight of populations is driven by changes in the environment from the start of life.

"For many, increased body weight is a form of malnutrition - excess energy supplying nutrients (protein, fat, carbohydrate and alcohol) and often not enough of all the other vitamins, minerals and myriad of other nutrients we can only get in the right combination from whole fruit and vegetables and other foods.

"On top of that regular physical activity keeps the functions of the body tuned and efficient. Particularly for children their growth is changed by their nutrition and physical activity patterns; these patterns imprint onto human function; effects that are not reversible but often only seen in later life - increased risk for cardiovascular disease, type 2 diabetes, stroke and cancer. This paper adds to the evidence that maintaining healthy function across the life course is essential. Action is needed at a population level to improve the food supply and promote a healthier environment.

"Note - the authors conclusions are based on the data being adjusted for age and smoking status - age we cannot control but smoking has profound ill effects on health - stopping smoking may cause weight gain but overall risk for an individual will be reduced."

Angela Berrill, Director of ABC Nutrition, comments:

"While many of us in New Zealand may be aware of the positive link between obesity and health conditions such as type 2 diabetes and heart disease, there has been limited local research about any associations with cancer - until now. A recent study investigated this relationship in Asia-Pacific populations and included participants from New Zealand.

" Research findings indicate that overweight and obesity are positively correlated to an increased risk of all cancer mortality, with a 21% higher risk for obese individuals compared to normal weight individuals. While Body Mass Index (BMI) was not adjusted for ethnic variations to cut off points, this still provides us with an indication of an association. However, more research is needed to gain a clearer picture; especially in relation to ethnicity and at which BMI values the associated cancer risk started to increase.

"Overweight and obesity rates in New Zealand continue to rise. Results from this study suggest there now may be an additional reason to maintain a healthy weight - reducing the risk of cancer. Key strategies to maintain a healthy weight include eating a balanced diet with a variety of fruit and vegetables, portion control and taking part in at least 30 minutes of physical activity every day."

Jan Pearson, Health Promotion Manager at the Cancer Society of New Zealand, comments:

"With the rapid growth of Asian populations in New Zealand these results highlight the need for comprehensive policies and programmes, and the provision of appropriate health services to address the needs of these communities."