14th August 2014 - According to research involving more than 5 million UK adults, having a higher body mass index (BMI) increases the risk of developing 10 of the most common cancers: uterus, gallbladder, kidney, cervix, thyroid, leukaemia, liver, colon, ovarian and breast cancers after menopause.
Researchers at the London School of Hygiene & Tropical Medicine and the Farr Institute of Health Informatics estimate that each year more than 12,000 cases of those 10 cancers are attributable to the patient being overweight or obese.
Study leader, Dr Krishnan Bhaskaran, says in a statement: "The number of people who are overweight or obese is rapidly increasing both in the UK and worldwide. It is well recognised that this is likely to cause more diabetes and cardiovascular disease. Our results show that if these trends continue, we can also expect to see substantially more cancers as a result."
This new study is the largest of its kind on BMI and cancer and it's been published in The Lancet.
Using data from GP records the researchers identified 5•24 million individuals aged 16 and older who were cancer-free and had been followed for an average of 7•5 years.
In all researchers looked at 22 of the most common cancers, which represent 90% of the cancers diagnosed in the UK. Risk was then measured according to BMI, after adjusting for things like age, sex, smoking and alcohol use.
They found a total of 166,955 people developed one of the 22 cancers studied and BMI was associated with 17 of those cancers.
Researchers found each 5 kg/m² increase in BMI was clearly linked with higher risk of cancers of:
Reacting to the study in a statement, Tom Stansfeld, health information officer at Cancer Research UK says: "This study of over 5 million people has found new and stronger links between obesity and several different cancer types, highlighting the number of cancers that obesity causes in the UK.
"Although the relationship between cancer and obesity is complex, it's clear that carrying excess weight increases your risk of developing cancer. Keeping a healthy weight reduces cancer risk, and the best way to do this is through eating a healthy, balanced diet and exercising regularly."
Dr Bhaskaran says: "There was a lot of variation in the effects of BMI on different cancers. For example, risk of cancer of the uterus increased substantially at higher body mass index; for other cancers, we saw more modest increases in risk, or no effect at all. For some cancers like breast cancer occurring in younger women before the menopause, there even seemed to be a lower risk at higher BMI.
"This variation tells us that BMI must affect cancer risk through a number of different processes, depending on the cancer type" he says.
There was some evidence that men with high BMI were at a slightly reduced risk of prostate cancer.
The study was funded by the National Institute for Health Research, Wellcome Trust and the Medical Research Council.
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