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?

Yesterday in the New York Times, Jane Brody reminded us of the importance of cancer prevention when focusing on tobacco, the leading cause of cancer in the US and the world. This preventable cause of cancer continues to be marketed, but how do we quantify the prevention efforts that range from international agreements to counter tobacco, to state taxes that reduce smoking and support prevention programs, to local ordinances that help smokers quit or help prevent experimentation and addiction among our youth?

However we do the sums to add up the costs of our prevention efforts, they typically pale beside the resources committed to our focused research on discovery and development of new drugs and strategies to speed diagnosis and treatment of cancer. As of 2006, our national expenditures on cancer treatment exceeded 104 billion dollars, and with the number of cases of cancer diagnosed each expected to double over the next 40 years, these costs can only continue to rise. The full details of these costs broken down by cancer site are summarized in the NCI Cancer Trends Progress Report 1009/2010 (see link for details).

Importantly, an FDA advisory panel has recommended against continued use of a drug that shows little benefit among women with advanced stage breast cancer. As advocates at the meeting noted, false hope is not worth paying for. As we move to more personalized approaches to care that are determined by the genetic make up of the patient and the specific tumor being treated, we must continue to refine our approaches to determine which drugs are effective in which patients and carefully focus therapies accordingly.

But, as we spend more than 100 billion dollars on cancer treatment each year, can we refocus our attention on cancer prevention? Primary prevention can substantially reduce the cancer burden. Quitting smoking saves lives – never starting is even better (Kenfield, Stampfer et al. 2008; Kenfield, Wei et al. 2010). Decreases in smoking among men over the past 40 years have resulted in significant reductions in male lung cancers. But women have not caught up and the numbers continue to rise (Edwards, Ward et al. 2010).  The value of prevention increases over time when messages remain constant or are refined as the science improves. The SunSmart prevention program in Australia highlights this approach and national success in countering the rise in melanoma. We however, continue to have increasing rates of melanoma in the US (Linos, Swetter et al. 2009). Our system rewards the development of “new approaches” rather than continuing to fund and use approaches that we already know work. In essence our priority for discovery overall application hinders progress in prevention. To bridge the gap from discovery to delivery and actual population health and wellness benefit, we need to fund programs that implement and sustain prevention that works. We also need to reward those who are committed to academic and local public health careers focusing on implementation and evaluation of programs that are known to work.

Contrasting prevention efforts with drug marketing is also helpful as it highlights sustained strategies to increase drug use (pharmaceutical detailing etc); whereas for prevention that is not focused on drugs our approaches are not as well coordinated and certainly not sustained. Take colorectal screening, for example, which can halve colon cancer mortality. We still have huge gaps in use of screening that persist even after access to care is covered through Medicare (Doubeni, Laiyemo et al. 2009; Doubeni, Laiyemo et al. 2010).

There are many successes of prevention over the years, but they get lost in the background, almost taken for granted once in place. On the other hand, new cases of cancer are diagnosed every day, pushing our systems of care to accommodate and ever increasing numbers of cancer patients. How do we balance these real world forces? Do you have ideas on how we might bring more political will to bear on sustaining prevention so we as a society reap the benefit?

References

Doubeni, C. A., A. O. Laiyemo, et al. (2009). "Socioeconomic and racial patterns of colorectal cancer screening among Medicare enrollees in 2000 to 2005." Cancer Epidemiol Biomarkers Prev 18(8): 2170-2175.

Doubeni, C. A., A. O. Laiyemo, et al. (2010). "Primary care, economic barriers to health care, and use of colorectal cancer screening tests among medicare enrollees over time." Ann Fam Med 8(4): 299-307.

Edwards, B. K., E. Ward, et al. (2010). "Annual report to the nation on the status of cancer, 1975-2006, featuring colorectal cancer trends and impact of interventions (risk factors, screening, and treatment) to reduce future rates." Cancer 116(3): 544-573.

Kenfield, S. A., M. J. Stampfer, et al. (2008). "Smoking and smoking cessation in relation to mortality in women." Jama 299(17): 2037-2047.

Kenfield, S. A., E. K. Wei, et al. (2010). "Burden of smoking on cause-specific mortality: application to the Nurses' Health Study." Tob Control 19(3): 248-254.

Linos, E., S. M. Swetter, et al. (2009). "Increasing burden of melanoma in the United States." J Invest Dermatol 129(7): 1666-1674.

Previously, it was estimated that 70% of cervical cancer is caused by just two strains of the human papillomavirus (HPV) – strains 16 and 18. Those are the same two strains that the HPV vaccine (sold under the name Gardasil in the US) protects against. HPV is a sexually transmitted disease and the vaccine protects women and girls against it if they are vaccinated before sexual contact with a partner carrying the virus.

New research out of Britain suggests the 70% is an underestimate and closer to 80% of cervical cancer may be caused by strains 16 and 18 – meaning closer to 80% of cervical cancer could be prevented with the vaccine.

Despite the promise of this cancer prevention approach, many in the US remain reluctant to vaccinate themselves, their children or members of their community. Estimates are that only 20-30% of eligible girls in the US are vaccinated (compared to nearly 80% in the UK and Australia). In talking about the power of the vaccine, the most common objection I’ve heard is based on the rumor that the vaccine causes more problems than it prevents. As I dug around the internet on a number of websites of questionable validity, it seems that this MISconception largely stems from a misunderstanding about the differences between correlation and causation.

Most public health and prevention research focuses on distinguishing between correlation and causation so it is not a trivial matter and is one that requires a lot of attention in our research. If I take a pill and get a headache, did the pill cause the headache and thus I should no longer take the pill? Perhaps. But based on so little information, it is equally reasonable to say “perhaps not!” The problem with this “study of me” is that there is no comparison – would I have gotten a headache if I hadn’t taken the pill? This is why we look for quality research to have both a group receiving the pill (or intervention in behavior change research) and a group that doesn’t receive the pill (or intervention). In randomized controlled trials, the population is randomly assigned to one group or the other. In observational studies, such as cohort studies, the researchers identify those who took the pill and those who didn’t and then follow them over time to see what happens. By measuring differences in the two groups, the researchers can not only determine if the pill had the beneficial effects desired AND if there were adverse events. Then they analyze the data to see if the number of benefits (or adverse events) differ between the two groups.

Returning to where we started, the researchers who conducted the trials of the HPV vaccine found the number (or rate) of events didn’t significantly differ between the girls getting the vaccine and those who didn’t get the vaccine, but the girls who got the vaccine were significantly less likely to test positive for HPV, which causes cervical cancer (and is likely also related to other cancers including oropharyngeal cancers), over the course of the study follow-up.

Dr. Charles recently posted over at KevinMD on the top 10 cost effective preventive medicine services.
1) Aspirin
2) Childhood Immunization
3) Smoking cessation
4) Moderating alcohol intake
5) Colorectal cancer screening
6) Hypertension screening
7) Flu immunization
8) Vision screening
9) Cervical cancer screening
10) Cholesterol screening

The exciting thing here is some of these cost effective strategies also relate to cancer and many are also on our Your Disease Risk list of the 8 best ways to prevent disease. This should seem obvious, but it is always a nice reminder that the most effective approaches for disease prevention are also often cost effective approaches.

But not always…

KevinMD also has a piece this week on a Health Affairs report showing that a diabetes management program costs slightly more overall than doing nothing over the 25 years of study. This doesn’t mean we shouldn’t manage diabetes, but it does show that cost and the best care aren’t always synonymous. Keep in mind however, a couple caveats about this report:
1) this is about the cost of diabetes management not diabetes prevention. True primary prevention is about strategies to keep the disease from ever being diagnosed (as Dr. Moore nicely notes in the comments on Kevin’s page)
2) the Health Affairs analysis focuses on the costs to Medicare as it is a follow-on on previous Congressional Budget Office reports that only examine more near-term (over 10 years) costs. That means the costs related to worker productivity, absence from work and quality-of-life aren't included. Given the close margin in "cost" the report found, it is likely that accounting for these additional "societal" costs would make diabetes management programs cost-effective. As with all cost-effectiveness analyses, the time line and definition of costs are key to the result.

As this week's Health Affairs notes, there are programs consumers want regardless of the cost. We seem to equate more care and more expensive care with better care regardless of the evidence for such programs being effective or cost-effective exists. Some expensive interventions are worth it, some aren't. Some inexpensive interventions are worth it, and some aren't. And too often, the decisions to pursue interventions or cover them isn't based on effectiveness.

In the June issue of the journal Cancer Epidemiology, Biomarkers & Prevention, University of Minnesota researcher DeAnn Lazovich and colleagues published a study further confirming the dangers of indoor tanning, finding significant increases in the risk of melanoma linked to regular tanning bed use (link).  She summarizes her findings and take-home messages in this nice little video:

As national trends have shown us all too clearly, keeping weight in check can be a difficult journey for many of us, and a lonely one at that. Success or failure when it comes to our weight is often pinned to us as individuals. Yet, individual actions are just the culmination of a broader web of influences in our lives. So, while it certainly comes down to my choice to have a carrot rather than a cookie or go play basketball rather than watch basketball on TV, other influences in my environment can help me make the healthier choice of the two. If my friends are big produce eaters, for example, I’ll be more likely to choose carrots. If my neighborhood has safe parks with basketball courts, I’ll be more likely to choose to play sports rather than watch them.

To have a real and broad influence on weight loss it’s important to make positive changes to the many factors that influence how much we exercise and how much (and what) we eat. In scientific terms, this is called the “ecological model of health behavior.” And while it’s not that important for most of us to know what it’s actually called, it helps researchers look at all the different areas in our lives that influence how we act.

Researchers, Sallis and Owens (Sallis & Owen, 1999), have detailed the key factors that help influence our health choices:

• Intrapersonal factors: These are basically the things within ourselves that influence our choices – our self-motivation, our learned behaviors, our physical abilities, for example.

• Social environment factors: These are the social and cultural factors that promote or discourage a healthy behaviors. These include things like how our friends accept or reject certain behaviors; the healthy (or unhealthy) choices our friends make, and how our broader culture helps promote or discourage certain behaviors.

• Physical environment factors: These include things within the natural environment (such as weather or geography) or the constructed environment (such as bike paths, sidewalks, or safe neighborhoods) that promote or discourage a healthy behavior.

All of these different factors push and pull and sway us to make certain choices. When they’re all aligned it’s much easier to make (and keep up) healthy choices in our lives (see figure). 


When it comes to weight loss and physical activity, research has shown that certain approaches that target one or more of these factors can have positive benefits. Here’s a sampling of findings.

Health care setting
One demonstrated successful approach to improving weight control and increasing physical activity is intensive counseling in a health care setting. These programs not only provide support for making healthy changes but also build solid skills on how to make such changes and keep them up over time. The Diabetes Prevention Trial showed that health care provider-based counseling could reduce weight and increase physical activity over a 24 month period and thereby prevent diabetes (Diabetes Prevention Program Research Group, 2002). A National Cancer Institute intervention based on physician counseling of patients with the “Five A’s” —assess, advise, agree, assist, arrange — has also been shown to be effective.

Interactive technology
Interactive websites and other technologies can also offer many of the same aspects of evidence-based behavior change counseling, including assessing current health behaviors, identifying barriers to change, developing supportive social networks, allowing the patient to set goals and select relevant activities, and arranging follow-up support. And there’s evidence that these technologies can successfully help support lifestyle behavior change (Glasgow et al, 2004).

These tools can also be used at homes, in community centers, in doctors’ offices, or practically anywhere on mobile devices, something that will increase their appeal even more to both busy patients and busy physicians. Studies will show which approaches are successful and which are not.

Physical environment and policy
Changes to public policy and the physical environment have a vast potential to influence large segments of the population simultaneously and, therefore, can often be less costly (on a per capita basis) and more enduring than approaches that focus on convincing individuals to be more active. Rather than simply persuading individuals to change, environmental and policy approaches aim to make it easier for individuals to choose and maintain activities that promote healthy weight. They do this by changing social norms (for example, making it more acceptable to commute to work by bicycle or foot or to exercise during lunch hour) or by changing the environment (for example, improving road and sidewalk conditions for pedestrians and cyclists or making workplace stairways as safe, well-lit, and accessible as elevators).

Given the inherent difficulties of evaluating such population-based approaches to behavior change, there are little published data on the effectiveness of environment and policy approaches to increasing physical activity. In a 1998 review of the topic, Sallis et al. found only seven published studies, with interventions ranging in complexity from the posting of simple signs encouraging the use of stairs to the opening of 14 publicly-funded recreation centers in Belfast (Sallis et al, 1998). Methodological flaws in these studies eventually precluded the authors from reaching firm conclusions about their efficacy.

Yet, lessons from smoking prevention show that policy choices can have major effects on healthy outcomes (Cummings et al, 2009). Each 10 percent increase in the tobacco excise tax finds about a 4 percent drop in smoking rates. And in New York City, broad smoke-free laws show significant drops in heart attack rates across the city in just a single year. Of course, weight loss isn’t tobacco, and nothing can stand in for solid evidence of the weight control benefits for policy and environmental changes, pointing to the need for rigorous evaluation of any such programs put into place.

Summary
Because the factors that influence weight control, diet, and exercise range from the individual to the environment, efforts to shift the whole population toward healthier weight, calorie, and activity levels will require emphasis on all of the intervention points mentioned above: health care settings, social networks, and environment. The challenge for prevention is to develop a comprehensive approach to physical activity and weight control that targets all of these aspects simultaneously.


Literature cited
Cummings KM, Fong GT, Borland R (2009). Environmental influences on tobacco use: evidence from societal and community influences on tobacco use and dependence. Annu Rev Clin Psychol 5:433-58.

Diabetes Prevention Program Research Group (2002) Reduction in the Incidence of Type 2 Diabetes with Lifestyle Intervention or Metformin. N Engl J Med 346: 393-403

Glasgow RE, Bull SS, Piette JD, Steiner JF (2004) Interactive behavior change technology. A partial solution to the competing demands of primary care. Am J Prev Med 27: 80-7

Sallis J, Owen N (1999) Physical activity and behavioral medicine. Vol. 3edn. Thousand Oaks, CA: SAGE Publications Ltd

Sallis JF, Bauman A, Pratt M (1998) Environmental and policy interventions to promote physical activity. Am J Prev Med 15: 379-97

KevinMD has had some great guest posts recently including one by Kenneth Lin (http://commonsensemd.blogspot.com/) on the need (or not) for cancer awareness. Dr. Lin references the recent Facebook campaign that had women posting their bra color to raise breast cancer awareness – which had me wondering whether anyone is really not “aware” of breast cancer (Dr. Lin similarly asks if we really need more awareness). The need for “awareness” raising is the same argument Susan G. Komen for the Cure and KFC used to justify their current Buckets for the Cure campaign since actual sales of the gigantic fried chicken buckets weren’t directly linked to fundraising. I actually think fundraising for cancer research is an important agenda item—foundations like the American Cancer Society, Komen, Breast Cancer Research Foundation, and Livestrong have contributed large sums of money to cancer research.

ACS funds some critical cancer prevention research through their Cancer Prevention Studies internally and is a large provider of external research funds as well. Similarly, Livestrong provides research dollars to cancer survivorship research and has played a key role in involving the community in cancer research. The dollars these organizations raise and direct to cancer research are really important. Organizations like this also use monies raised to provide important cancer education and advocacy services which wouldn’t be possible without the funds raised through sales of yellow rubber wrist bands or through events like Relay for Life. Which is why I find the “awareness” raising efforts so frustrating – they shouldn’t be about raising awareness, they should make it clear that the need is for support – for research, for education, for advocacy, for treatment when the patient can’t afford it and similar important endeavors. Creating opportunities for individuals who can’t afford financial contributions is also important – and I applaud efforts like that of the Love/Avon Army of Women to provide opportunities for women without breast cancer to be involved in research that will help advance our understanding of the causes of breast cancer. Individuals who want to do *something* about breast cancer (or any cancer) should be directed to sign up for efforts like this rather than posting their bra color on Facebook.