Being overweight boosts the risk of 10 common cancers, said a study of five million UK adults that prompted a call Thursday for tougher anti-obesity measures.
Researchers calculated that 12,000 cases of these 10 cancers every year in the UK were attributable to excess body weight.
And if current trends continue, "there could be over 3,500 extra cancers every year as a result," said a statement issued with the study, the largest of its kind, published in The Lancet medical journal.
Measured as a ratio of weight in kilogrammes-to-height in metres squared, a body mass index (BMI) of 25 to 29.9 is considered overweight, and 30 plus as obese.
"Each five kg/m2 increase in BMI was clearly linked with higher risk of cancers of the uterus (62 percent increase), gallbladder (31 percent), kidney (25 percent), cervix (10 percent), thyroid (nine percent), and leukaemia (nine percent)," said a statement.
Higher BMI also increased the overall risk of cancer of the liver (19 percent), colon (10 percent), ovaries (nine percent) and breast (five percent), although the effect on these four types was influenced by other factors.
Even within normal height-to-weight ranges, people with higher BMI numbers were more at risk, the researchers found.
Conversely, those with high BMI seemed to be at a slightly lower risk of developing prostate and premenopausal breast cancer.
The researchers used patient records on a nationwide data network and identified 5.24 million individuals aged 16 and older who were cancer-free when they were first registered.
Their health status was followed for an average 7.5 years, during which period nearly 167,000 in the group developed some form of cancer.
41% of uterine cancers
"There was a lot of variation in the effects of BMI on different cancers," said study leader Krishnan Bhaskaran of the London School of Hygiene and Tropical Medicine.
"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."
The team said excess body weight may account for 41 percent of uterine and 10 percent or more of gallbladder, kidney, liver and colon cancers in the UK.
Commenting on the findings, Peter Campbell from the American Cancer Society in Atlanta highlighted the need for policy changes to curb excess weight and obesity, a growing global problem.
These could include taxes on foods like sugar-sweetened drinks that are high in calories but low in nutrition, subsidies for healthier alternatives, and urban planning that encourages walking and other forms of exercise.
Earlier this week, another study in The Lancet said two in five American adults are expected to develop type 2 diabetes—a form of the disease caused mainly by physical inactivity and excess body weight.
Being overweight also puts people at a higher risk of heart disease and stroke.
A recent global analysis found that a third of adults and a quarter of children today are overweight.
More information: The Lancet, www.thelancet.com/journals/lan… (14)60892-8/abstract