Obesity, Cancer: Addressing the Knowledge Gap

Two impressive scientific publications on cancer came out Wednesday afternoon. They focus on two different but closely related aspects of cancer prevention. Considered together, they make a very simple case, one that AICR has been making for years:

We already know what causes millions of cancers. We know exactly what needs to be done about it — both as individuals, and as a country.

So the question we must ask, on the cusp of National Public Health Week, is:  Why aren’t we doing it?

The first publication is a the latest annual Report to the Nation on the Status of Cancer,  co–authored by the Centers for Disease Control and Prevention, the North American Association of Central Cancer Registries, the National Cancer Institute, and the American Cancer Society.

Several of the trends in the report are good news:  For both men and women, overall cancer incidence and mortality are down, albeit slightly, from the last report.

But in a Special Feature, the authors of the report note that smoking — long the number one cause of preventable cancers — is getting challenged for the top spot. Because while fewer and fewer Americans smoke, more and more of us are overweight and/or inactive.

And as AICR has been saying for years, overweight and inactivity cause tens of thousands of cancer cases in America every year. In fact, just by eating smart, staying lean and moving more, AICR estimates that we could prevent over 340,000 cancers per year in the US.

The second publication is a paper published in the journal Science Translational Medicine. Researchers from Washington University performed a series of calculations on cancer preventability and concluded, “More than half of the cancer occurring today is preventable by applying knowledge that we already have.”

The researchers estimate that collectively, smoking, overweight and obesity, inactivity, poor diets and other factors account for 54.5 percent of all cancer cases.

In the 2009 AICR/WCRF report, Policy and Action for Cancer Prevention, we computed our own estimates of cancer preventability.  What’s striking — and heartening — is that, although we crunched the numbers using a different method than the Washington University researches, our estimates are generally congruent then those found in the new paper. (NOTE: AICR’s estimates dealt with diet, activity and weight, and did not account for smoking.)

Bottom line? Not smoking is the single most important thing you can do to prevent cancer, and we must keep up tobacco control efforts.

But we’re dealing with a knowledge gap, here. Thanks to years of successful public awareness programs, an overwhelming majority of Americans know that smoking causes cancer. But far fewer know that obesity, inactivity and poor diets cause about a similar number of cancers per year.

The numbers outline the degree of the problem: Over the past decade, according to AICR’s Facts vs. Fears Survey of Americans (Word document), 92 percent or respondents, on average, are aware that tobacco causes cancer.

Over that same time period, awareness that obesity is a cause of cancer has averaged only 44 percent.

Awareness that physical inactivity raises cancer risk has averaged even lower — 39 percent.

April begins with Public Health Week. Check back here on the AICR Blog; we’ll be presenting a series of posts about this knowledge gap — and how we as a society can set about closing it.