Extra Weight May Increase Risk for Certain Cancers

Cancer risk associated with body mass index in UK study of obesity and excess weight

(RxWiki News) Many people want to slim down to cut their risks for heart disease and diabetes, but a new study suggests that being overweight may also affect cancer risk.

The new study, led by researchers in the United Kingdom, explored a potential connection between the rates of certain types of cancers and weight.

The study found that excess weight was associated with a greater risk for certain cancers, including uterine, gallbladder and kidney cancers.

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The authors of this new study, which was led by Krishnan Bhaskaran, PhD, of the London School of Hygiene and Tropical Medicine in the UK, wanted to explore the association between weight and specific types of cancer.

Dr. Bhaskaran and team used data from the Clinical Practice Research Datalink, which contains doctors' office records from 5.24 million people aged 16 or older in the UK. Patients were followed for an average of 7.5 years.

The study authors determined whether subjects were overweight by using body mass index (BMI) — a ratio of height and weight that measures body fat. A BMI of 25 to 29 kilograms per square meter (kg/m2) is typically considered overweight, and a BMI of 30 kg/m2 or higher is obese.

The study authors also considered 22 of the most common cancers in the UK, including breast, prostate, colon and lung cancers.

In total, 166,955 cases of the cancers were identified. After analyzing the data, the researchers found that 13 of the 22 cancers were associated with being overweight or obese, but the strength of this association varied among different types of cancer.

Dr. Bhaskaran and team reported that each 5 kg/m2 increase in BMI was associated with a 1.62-times increase in the risk of cancer of the uterus, 1.31-times increase in gallbladder cancer risk and 1.25-times increase in the risk of kidney cancer.

An increase in BMI was also associated with an increase in the risk of other cancers, including leukemia and cervix and thyroid cancers.

Based on their findings, Dr. Bhaskaran and team estimated that 41 percent of uterine cancers and 10 percent or more of gallbladder, kidney, liver and colon cancers could result from extra weight.

The researchers also estimated that an average population-wide BMI increase of 1 kg/m2 could cause an extra 3,790 cases of certain cancers each year in the UK.

The study authors noted that only patients with BMI data were included in the study — but the inclusion of a BMI measurement in these patients' records might be based on other weight or health issues. Further research could help confirm these findings and clarify a potential relationship between BMI and cancer.

The study was published online Aug. 14 in The Lancet.

Funding sources for the study included the National Institute for Health Research, Wellcome Trust and Medical Research Council. The authors disclosed no conflicts of interest.

Review Date: 
August 14, 2014