18.08.14
Researchers find more links between obesity and common cancers
Having a higher Body Mass Index (BMI) has been linked with an increased risk of developing 10 of the most common cancers, writes Alexandra Clarke.
More than 12,000 cases of these 10 cancers each year are attributable to being overweight or obese. Researchers at t he London School of Hygiene & Tropical Medicine have worked with the Farr Institute of Health Informatics to conduct the largest study of its kind on BMI and cancer, with over 5 million adults in the UK.
The researchers used data from GP records in the Clinical Practice Research Datalink (CPRD), whose founding director John Parkinson was interviewed by NHE when it launched.
They identified 5.24 million cancer-free people aged over 16, and examined how many of them developed the 22 most common cancers in the UK.
The researchers found that 166,955 people in the follow-up period developed one of the cancers, 17 of which were associated with BMI (individual factors such as age, sex, smoking status and socioeconomic status were adjusted).
Each 5kg/m² increase in BMI was associated with an increased risk in cancers of the uterus (62% increase), gallbladder (31%), kidney (25%), cervix (10%), thyroid (9%), and leukaemia (9%).
A high BMI was also associated with an individual’s overall risk of developing cancer of the liver (19% increase), colon (10%), ovarian (9%), and breast (5%), although these effects varied by underlying BMI or individual characteristics.
There is some evidence to suggest that having a higher BMI could slightly decrease the risk of prostate cancer and premenopausal breast cancer.
Lead author Dr Krishnan Bhaskaran, National Institute for Health Research Postdoctoral Fellow at the London School of Hygiene & Tropical medicine, explained: “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 increase 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 processed, depending on the cancer type.”
The 10 common cancers linked directly to obesity were: uterus, gallbladder, kidney, cervix, thyroid, leukaemia, liver, colon, ovarian, and postmenopausal breast cancers.
It was estimated that a population-wide 1kg/m² increase in BMI would result in 3,790 additional UK patients annually developing one in 10 cancers.
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