Study links obesity to more cancers
New research has found further evidence of the link between being obese and an increased risk of some common forms of cancer, and has found a number of less common cancers for which obesity also appears to be a risk factor.
The study also found that the link between obesity and bowel cancer was stronger in men than in women, and that the link between breast cancer and obesity was strongest in women from the Asia-Pacific region.
Researchers at the University of Manchester and Christie Hospital NHS Foundation Trust drew together data from 221 previously published studies, looking at a total of 282,137 cancer cases.
The findings, which are published in the Lancet medical journal, suggest that a BMI increase of 5 kg/m2 in men increases the risk of oesophageal (gullet) cancer by half, thyroid cancer by a third, and both bowel cancer and kidney cancer by a quarter.
There was also a slight link with rectal cancer and malignant melanoma in men.
In women, a similar increase in BMI increases the risk of womb cancer by 59 per cent, gallbladder cancer by 59 per cent, gullet cancer by 51 per cent, and kidney cancer by 34 per cent, and there was a slight link between increased BMI and postmenopausal breast, pancreatic, thyroid and bowel cancers.
In addition, the researchers found a slight link between increased BMI and leukaemia, multiple myeloma and non-Hodgkin's lymphoma in both men and women.
The researchers, who were led by Dr Andrew Renehan, concluded: "Increased BMI is associated with increased risk of common and less common malignancies.
"For some cancer types, associations differ between sexes and populations of different ethnic origins. These epidemiological observations should inform the exploration of biological mechanisms that link obesity with cancer."
Ed Yong, health information manager at Cancer Research UK, commented: "By combining the results of earlier research, this study confirms that a large number of different cancers are more common in people who are overweight or obese.
"After avoiding smoking, maintaining a healthy body weight is one of the most important steps we can all take to reduce our risk of cancer."