Lifestyle blamed for many cancers
Simple lifestyle and environmental changes could significantly help to cut the number of cancer deaths around the world each year, research suggests.
Experts linked more than a third of the seven million cancer deaths worldwide in 2001 to nine potentially modifiable risk factors.
These include poor diet, smoking, alcohol, obesity, lack of exercise and air pollution.
The Harvard University study is published in The Lancet.
The researchers calculated that of the seven million deaths from cancer in 2001, 2.43 million were linked to the nine risk factors.
The findings were based on a comprehensive review of scientific studies and other sources such as government reports.
The Harvard team and their collaborators also re-analysed some of the original data from the studies.
They concluded that in low and middle-income countries the most important risk factors were smoking, alcohol use, and low consumption of fruit and vegetables.
In high-income countries, smoking, alcohol use, and obesity played the leading role.
Deaths could be cut
Lead researcher Dr Majid Ezzati said that smoking was by far the most important risk factor for cancer - alone responsible for 21% of cancer deaths worldwide.
He said public health campaigns targeting smoking in the UK had led to a drop in deaths from lung cancer in the past few decades, and showed just how effective such campaigns could be.
He said: "Primary prevention through lifestyle and environmental interventions remains the main route for reducing the global cancer burden.
"If implemented, reduction of exposure to well-known behavioural and environmental risk factors would prevent a substantial proportion of deaths from cancer."