Obesity increases risk of 10 cancers- study
Obesity is a growing public health problem globally, which has largely been associated with lifestyle changes.
Being overweight and obese puts people at greater risk of developing 10 of the most common cancers, according to research published in the Lancet medical journal.
Scientists found individuals carrying extra weight could contribute to more than 12,000 cases of cancer in the UK population every year.
They warn if obesity levels continue to rise, there may be an additional 3,700 cancers diagnosed annually. The study of five million people is the largest to date to confirm the link.
Large numbers
Globally, doctors often warn being overweight can increase the risk of developing cancer, but this study highlights those forms of the disease where the risk is greatest.
Led by scientists from the London School of Hygiene and Tropical Medicine, the researchers gathered data on five million people living in the UK, monitoring changes to their health over a period of seven years.
They found each 13 to16 kilogramme of extra weight an average adult gained was linked firmly and linearly to a greater risk of six cancers. How big this risk was, varied depending on tumour type. Cancer of the uterus had the highest increased risk. Cancers of the gallbladder, kidney, cervix, thyroid and leukaemia had the lowest rise in risk.
People who had a high body mass index (calculated using weight and height) were also more likely to develop cancer of the liver, colon, ovaries, and post-menopausal breast cancer.
But the effects for these cancers were less clear-cut and were influenced by individual factors such as menopause.
Researchers say though obesity was associated with the development of the most common cancers, which represent 90 per cent of the cancers diagnosed in the UK, some showed no link at all. And there is some evidence to suggest a higher BMI is associated with a lower chance of getting prostate cancer.
Dr Krishnan Bhaskaran, who led the research, said there was a lot of variation in the effect of BMI on different cancers. For example, risk of cancer of the uterus increased substantially at higher body mass index.
“This variation tells us BMI must affect cancer risk through a number of different processes, depending on cancer type,” said Bhaskaran.
Tom Stansfeld, at Cancer Research UK, says regular exercise and a balanced diet are crucial.
