The U.S. Obesity Epidemic and Surging Liver Cancer

If there is one truism that trumps everything else these days about U.S. health, it’s that America is a chubby country that keeps getting fatter.

The consequences seep into every corner of the nation’s medical state, including the surprising fact that obesity and the type 2 diabetes it causes are likely pushing up the incidence of liver cancer—hepatocellular carcinoma—to unprecedented heights.

courtesy Wikimedia Commons

When I covered Digestive Disease Week in San Diego recently, one of the biggest stories I heard was that U.S. liver-cancer rates tripled from 1975-2007, and that the numbers continued to rise from the mid to the late 2000s. (My full report on this is here).

Granted, factors other than just obesity play into the liver cancer surge, notably the sizable number of Americans infected with either hepatitis B or C virus, and the fact that as they age their risk for developing hepatocellular carcinoma rises.

But new U.S. infections by hepatitis B and C are largely under control these days (although people infected elsewhere continue to emigrate to the United States). The part of the booming liver-cancer story that is by no means under control is the obesity part.

Every time I see a new CDC map for U.S. obesity prevalence, the colors on it keep getting redder and darker (the CDC’s code for higher prevalence rates).

courtesy CDC

courtesy CDC

Earlier this year, the CDC reported a 36% obesity prevalence rate for the entire U.S. population–and still on the rise–and just a few weeks ago we heard that obesity among children and adolescents had hit a new high of 17%. With obesity seemingly on an unchanging upward trajectory, one can only wonder what rates of liver cancer it might produce in the future. Obesity carries a special relationship with the liver, and it’s not pretty. Just consider any goose headed to a foie-gras future.

Until now, the evidence linking obesity and liver cancer, and type 2 diabetes and liver cancer has been epidemiologic. Compelling, but just an association. At DDW, a new study provided more observational data on the diabetes-liver cancer link, and while still circumstantial it further supports the notion and also carries an intriguing punchline.

The study, done in Taiwan, examined 97,000 hepatocellular carcinoma patients and 195,000 matched controls. The analysis showed that people with diabetes had a two-fold increased risk for liver cancer compared with those without diabetes. Even more striking, the analysis also showed that people with diabetes treated with the oral hypoglycemic drug metformin had their risk for liver cancer cut in half compared with those not on metformin, and those with diabetes treated with a glitazone drug (such as pioglitazone–Actos) had their risk cut nearly in half.

The best solution would be if people avoided obesity and type 2 diabetes all together. Both conditions cause a lot of medical problems, and this new evidence indicates more strongly than ever before that liver cancer is one of them.

—Mitchel Zoler (on Twitter @mitchelzoler)

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Filed under Endocrinology, Diabetes, and Metabolism, Epidemiology, Gastroenterology, IMNG, Internal Medicine, Internal Medicine News, Oncology

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