If I was not in the oncology field, I'd be pretty confused about trends in cancer incidence and death. A recent headline said something like: “More Americans Than Ever Are Dying of Cancer!” But if you read the fine print, you see that what the authors meant is that we have a successfully aging population. With age comes a greater chance of getting cancer, and because we have an expanding population, the absolute number of people dying of cancer is growing. Makes sense!
What the article didn't emphasize was that even with an increasing incidence of cancer, the age-adjusted mortality rates, at least for the 4 most common cancers (lung, colorectal, breast, and prostate cancers), are plummeting. That's the real news!
But the fear factor is out there. And we would all agree that avoiding cancer is an important goal. When you consider lifestyle and behavior, it gets simple. Avoid tobacco products. That's black and white. Maintain a healthy body mass index. There are charts and measurements to guide us there. Limit red meats. Now it starts to get tricky. What is “limited”—twice a week? How strong is the dietary data? And then there's exercise! But how much? Should we all be running marathons?
Thankfully, we have new guidance from Arem et al1 at the NCI. In a study published in June, they reported results from an analysis of data from more than 600,000 patients. These data came from 6 studies pooled in the NCI Cohort Consortium, in which subjects self-reported leisure time activity. The authors analyzed this data for associations with all-cause and cancer-specific mortality and compared the results with the 2008 Physical Activity Guidelines for Americans.2 In those guidelines, minimal activity was defined as 75 minutes of vigorous-intensity activity or 150 minutes of moderate-intensity aerobic activity, weekly.
The good news is that even at only 1 to 2 times the minimum recommended level, the reduction in cancer-specific mortality was 21%. That's pretty good! So, is more activity better? Well, a little. At 10 times the recommended minimum, the risk was further reduced, but only to 31%. But excessive and extreme activity did not appear to be associated with any increased risk of overall mortality. So those of you preparing for your next Iron Man competition can relax!
These results show us that being a couch potato is clearly not going to get us anywhere. But we see that we don't need to go overboard either. If we all just committed to meeting the minimum recommended level of activity, we could expect a significant reduction in cancer incidence.
So, what does this mean for the professional oncology community? The public and even other health care professionals look to us for guidance about cancer prevention. We need to speak out and promote healthy lifestyles to our patients and in our communities. This means getting our school systems to invest more in physical education, asking companies to promote and allow exercise in the workplace, and making sure our city leaders provide adequate recreational space for our communities.
Now, if you'll excuse me, I need to go take a walk.
Arem H, Moore SC, Patel A et al.. Leisure time physical activity and mortality: a detailed pooled analysis of the dose-response relationship. JAMA Intern Med 2015;175:959–967.
US Department of Health and Human Services. 2008 Physical Activity Guidelines for Americans. October 2008. Available at: http://www.health.gov/paguidelines/pdf/paguide.pdf. Accessed July 31, 2015.