HOW TO PREVENT CANCERS

There was a very nice piece this morning on NPR's Morning Edition building on a study released earlier this month that found that being persistently overweight from young adulthood on can have a profoundly negative social and economic impact on individuals - this in addition to the already well-documented health effects of overweight and obesity (NPR story) (study link). After a quick review of the results and implication of the 20-year study, the story, by Patti Neighmond, goes on to discuss two issues very important to this blog's contributors:  the importance of prevention and creating a supportive environment when it comes to controlling the obesity epidemic.

We've detailed the individual choice/environmental influence relationship in a number of other posts (related posts), but it's good to see (er, hear) it gaining more and more momentum in the media, government, and beyond.

Results from an exciting new analysis were released today and highlight the important advances that are being made in understanding how energy expenditure relates to cancer. The results, from the American Cancer Society’s Cancer Prevention Study show that individuals who report more time spent sitting (6 hours/day or more) have a higher risk of mortality than those who report little sitting (less than 3 hours/day). Importantly, this effect is independent of the amount of time the individuals reported engaging in physical activity. As we've previously reported, physical activity also predicts obesity, chronic diseases and mortality.

I spent last week at an exciting workshop at NIH addressing how we measure physical activity and sedentary behaviors. While objective devices like pedometers and accelerometers help us get information on certain physical activities and can help estimate energy expenditure, they don’t tell us about the context or type of behaviors. This is really important when thinking about sedentary behaviors, which are increasingly being shown to have an important role in obesity and chronic disease. Some sedentary behaviors are modifiable, such as TV watching. While others, like time spent driving to work, may be largely unchangeable. Great work is being done in the US, UK, and Australia to improve our understanding of how people spend their sedentary time so that interventions can better target behavior change and measure effectiveness of interventions.

To understand the ACS results a bit better, think about a couple examples. Most of us on the CNiC team spends our days sitting at a desk, writing papers, and analyzing data. We all try to get at least 30 minutes of moderate intensity activity a day, but if we spent more of the day moving about, we’d be better off. In fact, standing during some of those long meetings we have burns more calories and may help improve health. In contrast, plenty of people are on their feet all day (which brings back bad memories of my days in the retail and service sectors, which left me exhausted!), but may never be active enough at a pace to increase their heart rate enough to qualify as “moderate intensity” activity. As a result, in many research studies, these people would be considered “sedentary”. What today’s study from Alpa Patel and colleagues suggests is that these busy-on-their-feet people, even though they may not meet the physical activity guidelines, are doing better than those folks who are in an office and don’t get any physical activity. Of course, that doesn’t mean those who are busy on their feet couldn’t do better by adding in some moderate intensity activity each day!

The current recommendations are to get at least 30 minutes of activity of at least moderate intensity each day. This means walking, gardening, dancing, cycling, or easy running - really, anything you enjoy that gets you moving and your heart rate up. For an extra, and increasingly important, boost, do something each day that cuts down on the amount of time sitting.  Stand at a counter and work on your computer for a while; choose to stand on the bus rather than sit; or take the occasional stand-and-stretch break at school, home, or work.  They may all seem like little things but add them all up, and they can have an important impact on your health.

This week, the New York Times reported (story) on the status of our nation's efforts to control hepatitis C infections, which look grim in some ways, as rates of infection, and associated liver transplants continue to rise.  Some experts are excited about a new screening test which can detect hepatitis C infection immediately without waiting for outside lab testing.  This isn't a screening test for liver cancer, given that, as we've noted before (previous post), the test hasn't been evaluated for its effect on mortality.

In fact, only a fraction of those infected with hepatitis C go on to develop cirrhosis or liver cancer, and there is no test to identify those at greater risk of these serious complications.  However, it is hoped that with the improved treatments for hepatitis C infection now available, and described in the NY Times article, a test to screen for infection will lead to treatment and clearance of the infection, and thus, lower rates of liver cancer and liver cancer mortality.  But neither of these outcomes has yet been evaluated. And this is the big open question, since it isn't clear the treatment regimens are actually making a difference on rates of either cirrhosis or liver cancer, since many of those treated would never have gone on to cirrhosis or other serious problems.

Clearly, those who have been following CNiC in particular and cancer prevention news in general for a while are seeing some parallels here with other screening debates (previous screening posts), most notably the debate surrounding the risk and benefits of PSA screening for prostate cancer. However, we know that plenty of people prefer an approach for themselves that involves more testing as it makes them feel more secure in their health. Do you think promoting hepatitis C screening is premature or a way to help us find those with the infection and get them treated? Would you consider getting screened? Is this a good use of cancer prevention resources or should other programs receive priority?