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High BMI Increases Risk for Ten Cancers

Higher BMI increased individuals’ risks for 10 common cancers, according to results of a population-based cohort study conducted in the UK….

More than 12,000 cases of these malignancies each year in the United Kingdom can be attributed to patients being overweight or obese, and nearly 4,000 more of these cancers could occur each year if the average BMI of the country’s population continues to increase, results showed.

Researcher Krishnan Bhaskaran, PhD, a National Institute for Health Research postdoctoral fellow at London School of Hygiene & Tropical Medicine, said in a press release, "The number of people who are overweight or obese is rapidly increasing, both in the UK and worldwide." "It is well recognized 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."

Bhaskaran and colleagues collected data from the UK Clinical Practice Research Datalink, which contains primary care records from about 9% of the country’s population. Researchers used the data — which include information about specialist referrals, hospital admissions and diagnoses made in secondary care — to assess the associations between BMI and 22 common cancers.

The analysis included 5.24 million individuals, of whom 166,955 developed one of the 22 cancer types of interest. Data was collected over 25 years.

Results showed each 5 kg/m2 increase in BMI was associated with increased risks for uterine cancer (HR=1.62; 99% CI, 1.56-1.69), gallbladder cancer (HR=1.31; 99% CI, 1.12-1.52), kidney cancer (HR=1.25; 99% CI, 1.17-1.33), cervix cancer (HR=1.1; 99% CI, 1.03-1.17), thyroid cancer (HR=1.09; 99% CI, 1-1.19) and leukemia (HR=1.09; 99% CI, 1.05-1.13).

Results also showed higher BMI increased overall risks for liver cancer (HR=1.19; 99% CI, 1.12-1.27), colon cancer (HR=1.1; 99% CI, 1.07-1.13), ovarian cancer (HR=1.09; 99% CI, 1.04-1.14) and postmenopausal breast cancer (HR=1.05; 99% CI, 1.03-1.07). However, underlying BMI and other individual characteristics — such as gender and menopausal status — influenced those associations.

Based on their results, if causality is assumed, researchers determined 41% of uterine cancers and at least 10% of colon, gallbladder, kidney and liver cancers could be attributed to excess weight.

"There was a lot of variation in the effects of BMI on different cancers," Bhaskaran said. "Risk of cancer of the uterus increased substantially at higher BMI. 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 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."

Practice Pearls:
  • Obesity does not discriminate among the majority of these cancers
  • Obesity is a key cause of unnecessary suffering and death from many forms of cancer
  • 41% of uterine cancers and at least 10% of colon, gallbladder, kidney and liver cancers could be attributed to excess weight.

Bhaskaran K. Lancet. 2014;doi:10.1016/S0140-6736(14)61172-7.