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.


5 thoughts on “Obesity, Cancer: Addressing the Knowledge Gap

  1. As a dietitian, we have put emphasis on obesity for a long time. And we always talk about calories and exercise, but most people do not realize that exercise will not cause you to lose weight. It will help you keep your muscles which have the burners to burn the calories. And for those of us who have been fighting weight all our lives, we know that fat is not good for us – but only a few know that it causes the inflammation that causes the irritation that causes the cancer. And we have not realllllllllyyyyyyyyy found out why the body plateaus at about 5-15% weight loss. – and yet that little bit of weight loss is helpful to the body. The last comment is that we have not found a way to keep the weight off. There is about 95% recidivism and we all experience it. There are lots of questions yet to answer before we blame people for gaining weight. Have you noticed it is happening all over the earth?

  2. Paragraph 11 – surely you mean “Quitting” smoking is the single most important thing you can do to prevent cancer??

  3. This is a question. I noticed in the blog you mention only that only 44% of people are aware of obesity as a risk factor and only 39% aware of physical activity. In the word document graph it is 51 and 46% does that reflect newer data?

    • Good question. The 51/46 numbers are, indeed, the latest (2009) findings. The 44/39 figures mentioned in the post are the five findings from across the past decade (read: the 01, 03, 05, 07 and 09 surveys) averaged together.

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