Wednesday, July 28, 2010

Obesity: Broad Reach, Broad Fixes

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.

Tuesday, July 27, 2010

Just Sitting Around Really IS That Bad

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.

Friday, July 23, 2010

Screening for Hepatits C?

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?

Wednesday, July 21, 2010

Treatment, costs, and the value of cancer prevention

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?

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.

Tuesday, July 20, 2010

Screening, early detection, and risk reduction

While awareness continues to grow that screening for breast cancer, like other screening tests, aims to detect cancer earlier, when it is more successfully treated, it is clear that screening tests are not perfect and those who test positive require additional follow-up to confirm the diagnosis and chose an appropriate therapy. Equally important, but less often the focus of visits to health care providers, is the potential to prevent or reduce the chance of ever developing cancer. We have discussed some of the breast cancer prevention strategies in recent posts, such as drugs, and weight loss. But you might ask, how do we know what level of risk for cancer we actually have? While a growing number of tools are available on web sites for “risk estimation” lets consider some of the “behind the screen” realities here.

Risk is a person's chance of getting a disease over a certain period of time. There are many different ways to present risk. In addition to age, a number of genetic factors (summarized most readily in family history of the disease) as well as lifestyle (including smoking, weight gain, physical activity, diet, alcohol) and infections may contribute to risk. Summing up the contribution of these factors in addition to age, one can estimate the risk of developing a specific disease in a given number of years (say 5-year risk) or over a lifetime. Of course, this risk is only an estimate. It can be presented as a numeric value or as a word classifying the level of risk compared to the average risk for someone of the same age. Calculating an individual's risk of disease is an inexact science. In the end, one either gets the disease or remains free from it, but at the outset risk of future disease falls along a gradient.  In Your Disease Risk, we estimate your risk of ever developing a disease in your lifetime compared to an average person who's your same age and sex.

In addition to focusing on the actual number or word classification for the level of risk, we believe that risk estimation can be helpful to classify level of risk. With this information one can then identify steps to take to reduce risk. The higher one is above the average for your age, the more things one might consider doing or at some level one takes drugs (e.g., cholesterol lowering drugs) to reduce the risk. Even with this reduction in cholesterol, risk is not removed to zero – every year some patients taking cholesterol lowering drugs still have heart attacks. Likewise for blood pressure medications. That said, these risk reduction strategies each prevent many thousands of cases of heart disease and stroke each year. As we recently noted (see post), heart disease continues to decline in populations that adhere to risk reduction strategies.

For Heart disease, the data from the Framingham Heart Study were taken to develop the risk prediction model that has been widely used in practice to guide prevention strategies that primarily focus on blood pressure and cholesterol. To this we add the lifestyle factors that other population studies, many modeled on the Framingham Heart Study, have shown are also related to heart disease risk.  For breast cancer we include a broad range of factors and can build substantial differences in risk between the top categories and the bottom. Likewise for colon cancer we have almost 10-fold differences in risk between the those in the highest category of risk and those in the lowest risk group, with healthiest lifestyle.

Risk reduction
As with any screening test, there should be a follow-on from the estimation or assessment of risk. Just as it is unethical to screen for a disease that does not have effective therapy, so it is likewise unethical and misleading to estimate risk and not also have available to those who get the risk estimate a summary of ways things they may do to lower their risk. Following this approach when we estimate risk at our web site, we highlight steps you can take to lower your risk.

Friday, July 16, 2010

Preventing Cervical Cancer – the value of the HPV vaccine.

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.

Thursday, July 15, 2010

Does Prevention Pay?

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.

Later age at first birth and increase in breast cancer risk

A British media story today points to later age at first birth as a major cause of increasing breast cancer rates in the UK (see story). This is not news, though increasing knowledge about causes of breast cancer is useful. We have known for decades that the later a women ahs her first birth the larger the adverse effect of this birth on her lifetime risk of breast caner. In fact, if she has only one birth say at age 35 her risk is higher for life by about 16% compared to a women who never has children, on the other hand, if she has her first birth at age 20 and has 4 children spaced 3 years apart, then her risk is 27% lower than the woman who ahs no children (Colditz and Rosner 2000). Thus age at childbirth and number of children together play an important part in driving the population risk of breast cancer.

Traditional low income countries have an added factor at play – age at menarche or first menstrual period. In low income countries and before industrialization average age of onset of menstrual periods is typically around 17 – and so the time from menarche to first broth is shorter than in our post industrial civilization where menarche is now at 12 or younger, on average, and age at first birth is rising – to higher than 30, on average, in Holland.

Asia as an example of rapid changes in risk factors and breast cancer incidence
We have previously estimated the increase in breast cancer incidence in China expected due to the changes in reproduction among women (Linos, Spanos et al. 2008). Likewise, reports from Singapore (Seow, Duffy et al. 1996) and Hong Kong point to secular trends in breast cancer incidence as women progress through economic transition. Recent media attention has pointed to the rapid decline in fertility in Korea. As the Economist noted, this decline in Korea from 6 births per 1000 women in 1965 to 2 in 1980 is more rapid than seen in Europe- for example Britain decreased this same magnitude over a  span of 120 years.

Also consistent with a long transition of industrialization impacting reproductive profiles, age at menarche has decreased quite rapidly in Korea. The third Korean National Health and Nutrition survey included 3562 women born from 1920 to 1985. Mean age at menarche decreased from 16.90±1.25 years for women born between 1920 and 1925 to 13.79±1.37 years for those born between 1980 and 1985, indicating a downward trend of 0.68 years per decade (95% CI, 0.640.71) in age at menarche. Mean age at menarche of girls born between 1986 and 1995 was 13.10±0.06 years.

Ahn and colleagues note the increase in breast cancer in Korea (Ahn and Yoo 2006). The median age at diagnosis is 47. Over the 8-year period form 1996 to 2004 the proportion of cases with menarche less than 13 rose from 8 to 13%. In a series of 5001 cases treated from 1989 to 2004 (Son, Kwak et al. 2006) the median age at diagnosis rose from 44 in 1991 to 46 in 2003 and the proportion of cases ER positive was 57.1% and PR positive 50.8% . For women in Korea, ages 45-49 the rate of breast cancer in 2002 was 90 cases per 100,000 women. This is still lower than that for white or Asian women in the USA, where the national registry data show a rate of around 60 per 100,000 women ages 45 to 49.

Literature cited

Ahn, S. H. and K. Y. Yoo (2006). "Chronological changes of clinical characteristics in 31,115 new breast cancer patients among Koreans during 1996-2004." Breast Cancer Res Treat 99(2): 209-214.
Colditz, G. and B. Rosner (2000). "Cumulative risk of breast cancer to age 70 years according to risk factor status: data from the Nurses' Health Study." Am J Epidemiol 152(10): 950-964.
Linos, E., D. Spanos, et al. (2008). "Effects of Reproductive and Demographic Changes on Breast Cancer Incidence in China: A Modeling Analysis." J Natl Cancer Inst 100: 1339-1341.
Seow, A., S. Duffy, et al. (1996). "Breast cancer in Singapore: Trends in incidence 1968-1992." Int J Epidemiol 25: 40-45.
Son, B. H., B. S. Kwak, et al. (2006). "Changing patterns in the clinical characteristics of Korean patients with breast cancer during the last 15 years." Arch Surg 141(2): 155-160.

Tuesday, July 13, 2010

Video: No Such Thing as Safe Tanning

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:

Carrot or Cookie: What Influences our Weight Loss Choices?

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.

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

Monday, July 12, 2010

All for One and One for All: The Importance of Keeping Tobacco a Key Part of Health Policy and Promotion

“…the prevalence of smoking in the United States hovers at 20%, more than 8 million people are sick or disabled as a result of tobacco use, and smoking kills 450,000 Americans annually.”

In a new Perspective on the New England Journal of Medicine's site (link), Stephen Schroeder, MD and Kenneth Warner, PhD  make the strong case for continuing our broad and largely effective efforts to curb tobacco use.  While high tech scans and exotic drugs may be more alluring and environmental contaminants scarier (previous post), tobacco remains a hugely important player in the nation’s health and deserves a great deal of attention.  It causes nearly a third of all cancers and is a major cause of heart disease, stroke, chronic bronchitis and emphysema. 

It’s easy to think that the battle against big tobacco has been won, but with rates of smoking leveling off in recent years, and the funding of some anti-tobacco programs being cut, the potential benefits of keeping up the fight remain enormous and shouldn’t be abandoned for other efforts with less clear potential.

With health care reform becoming law, prevention seems to be gaining more traction than it’s had in recent years.   We know that healthy diet, regular exercise, weight control, and not smoking can prevent the majority of chronic diseases.  None of these can be left behind as we move forward on all fronts.

Wednesday, July 7, 2010

What's the point of posting your bra color?

KevinMD has had some great guest posts recently including one by Kenneth Lin ( 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.

Untapped Benefits of Physical Activity and Weight Loss in Breast Cancer Prevention

Last week we commented on the data from the Nurses’ Health Study II showing that bike riding could reduce weight gain in premenopausal women. This is just one of many strategies available to women to increase exercise or physical activity, control their weight, and reduce their risk of breast cancer. Why do we focus on physical activity and weigh control for breast cancer prevention? The answer lies in the desire we hear from women to avoid breast cancer, to not opt for the drug strategy and to remain healthy. Below I summarize the evidence that weight loss and increases in activity could have as big a benefit in risk reduction as drug strategies for prevention. While the evidence is not yet in from a randomized controlled trial, the overall weight of evidence points to both short and long term benefits in quality of life , diabetes risk, and changes circulating hormone levels, which we refer to as intermediate markers for breast cancer.

Breast Cancer Today - a Solution
The majority of postmenopausal breast cancer is estrogen receptor positive, driven by endogenous or exogenous hormones and arise in a population of US women who are increasingly in positive energy balance as expressed by sedentary lifestyle and overweight or obesity, a trend that has increased in national data over the past 20 years. At least 70 percent of US women over 50 are sedentary and fail to meet national guidelines for activity and among obese women only 20 percent meet recommendations; over 62 percent are overweight or obese1. Prevalence rates are even higher among African American women. While white women 40 to 59 have a prevalence of obesity of 35.7 percent; African America women have a prevalence of 51.7 percent and this excess persists in women 60 and older 1. Previous studies by McTiernan show that the combination of weight loss and increase in exercise is necessary to achieve the greatest reduction in estradiol 2.

Energy balance and endogenous hormones. Among postmenopausal women, physical activity may lower breast cancer risk by reducing fat stores, which convert androstenedione to estrone 3-4. Physical activity may also increase levels of sex hormone-binding globulin, which would reduce bioavailable estrogens5.  Increasing activity associated with weight loss has produced the greatest reduction in estradiol 2. Increased physical activity also reduces insulin resistance and hyperinsulinemia 6, which may also be related to breast cancer 7. The relation of physical activity to breast cancer risk has been addressed in over 100 case-control and cohort studies 8. The most compelling evidence for long term physical activity and breast cancer risk comes from studies among premenopausal women. Bernstein noted that higher levels of physical activity related to later onset of regular menses 9 and subsequently we showed that sustained higher activity levels through premenopausal years produced similar results 10. Risk was reduced by approximately 40% among those who were consistently most active. These levels of activity may not be sufficient to modify hormone levels in premenopausal women 11, but are sufficient to impact insulin metabolism 12 and risk of type II diabetes 13 in women. Polymorphisms in the IGF pathway are related to mammographic density 14 a strong risk factor for breast cancer 15. The insulin receptor is, however, a significant major predictor of reduced disease free survival in women with node negative breast cancer 16, and supports the potential importance of the IGF pathway and insulin in breast cancer 17-18.

Obesity. Postmenopausal adiposity is an established risk for breast cancer 19-20. Components of energy balance indicate that highest energy intake, highest BMI and lowest energy expenditure may combine to more than double risk of breast cancer 21. Studies of insulin resistance in the face of energy balance suggest that C-peptide and IGF-1 are related to levels of leisure time physical activity and may mediate in part the relation between adiposity and breast cancer risk 22.

Sex steroid hormones, aromatase, and risk of breast cancer.  Endogenous steroid hormones play a key role in the etiology of breast cancer.  Reproductive factors such as parity and age at menopause influence breast cancer risk6.  In addition, selective estrogen receptor modulators (SERMs) decrease breast cancer risk in both premenopausal and postmenopausal women 23 but have substantial side effects. The association of circulating estrogen and androgen levels with risk is well established among postmenopausal women 24-25. Combined data from nine prospective studies show that circulating levels of estradiol, free estradiol, and testosterone levels are independently related to increased risk for beast cancer. Comparing the highest to lowest quintile of estradiol showed a relative risk of 2.58 (1.76-3.78; p trend<0.001) 24 comparable in magnitude to the initial reports of cholesterol and heart disease from Framingham in the 1960s 26. Similar evidence is beginning to accumulate among premenopausal women 27.

Among postmenopausal women, adiposity is the major predictor of estrogen levels, as the adipocyte (fat cell) is the primary locus for expression of aromatase 28-29. Estrogen biosynthesis is encoded by a single gene – aromatase, inhibition of which blocks estrogen production, and among women with breast cancer such inhibition has a dramatic treatment effect 30. Variants in cyp19 (aromatase cytcochrome P450) are related to circulating hormone levels but have not yet been shown to relate to breast cancer incidence 31. Maximizing changes in diet and energy balance as modifiers of this relation could produce large reductions in hormone levels and hence cancer risk.

In summary, maximizing weight loss and increasing activity will most likely produce the greatest reductions in estradiol and insulin levels leading to the greatest reductions in breast cancer risk. Strategies that combine an increase in exercise (energy expenditure) and dietary changes to limit excess energy (caloric) intake, can maximize and sustain changes in energy balance and weight loss then the reduction in breast cancer risk may be greater.

Who could gain most from a prevention strategy?
Postmenopausal women who are overweight or obese are an ideal starting point, though all women can gain in the long run from adopting these strategies. The Diabetes Prevention Trial which had targets of seven percent weight loss (10 pounds for a woman who weighs 150 pounds) and 150 met hours of activity per week, showed that lifestyle changes could be sustained and also reduce risk of disease. Changes at two years were a decrease in weight (six percent weight loss) and a significant increase in hours of physical activity. These changes resulted in a significant reduction in new cases of diabetes.

If we take the risk reduction we observed among postmenopausal women who lost weight and kept it off after menopause in the Nurses’ Health Study32, we might expect a 15 percent reduction in breast cancer based on the weight change. However, with an increase in physical activity having an independent effect on breast cancer risk from that of weight change, the total reduction in risk of breast cancer might be substantially greater. If the combination of walking and weight loss are sustained and add further support for improved energy balance and sustained weight loss, then a target of 20 or so pounds lost, and kept off after menopause, becomes achievable. Such sustained weight loss should produce a risk reduction as high as 50 percent or more based on data from the Nurses’ Health Study among postmenopausal women who had never used postmenopausal hormone therapy.  Clearly heavier women who can sustain weight loss of greater magnitude stand to gain even greater reduction in breast cancer risk while those who are less overweight will also achieve reduction but to a lesser extend. The benefits for diabetes risk, heart disease, and bone strength to avoid osteoporosis all add to the benefits of lower breast and colon cancer risks.

How big could the benefit be?
In the USA, based on 2010 population projections, there are 35.5 million women ages 50 to 69 and an expected 114,300 cases of invasive breast cancer in this age range. As the US population structure continues to age the number of cases will continue to rise. Benefits are also likely to be substantial for the 22 million women ages 70 – 84 in 2010. If 50 percent of invasive breast cancer cases are prevented through an overall population increase in physical activity and weight loss after menopause, at least 57,000 cases of breast cancer among women 50 to 69 years of age could be avoided each year. 

Simple lifestyle changes to increase activity and reduce excess energy intake to achieve and sustain weight loss could then be equal to the potential benefit of drug therapy without all the adverse effects, and with the added benefits of diabetes prevention, reduction in cardiovascular disease, and potentially other chronic disease risks.

We welcome feedback on strategies you may have used to help sustain increases in physical activity and to achieve weight control.


1.            Flegal KM, Carroll MD, Ogden CL, Curtin LR. Prevalence and trends in obesity among US adults, 1999-2008. JAMA. Jan 20 2010;303(3):235-241.
2.            McTiernan A, Tworoger SS, Ulrich CM, et al. Effect of exercise on serum estrogens in postmenopausal women: a 12-month randomized clinical trial. Cancer Res. Apr 15 2004;64(8):2923-2928.
3.            Siiteri PK. Adipose tissue as a source of hormones. Am J Clin Nutr. 1987;45(suppl):277-282.
4.            Cauley JA, Gutai JP, Kuller LH, LeDonne D, Powell JG. The epidemiology of serum sex hormones in postmenopausal women. Am J Epidemiol. 1989;129:1120-1131.
5.            An P, Rice T, Gagnon J, et al. A genetic study of sex hormone--binding globulin measured before and after a 20-week endurance exercise training program: the HERITAGE Family Study. Metabolism. Aug 2000;49(8):1014-1020.
6.            Stoll BA. Adiposity as a risk determinant for postmenopausal breast cancer. Int J Obes Relat Metab Disord. May 2000;24(5):527-533.
7.            Kaaks R. Nutrition, hormones, and breast cancer:  Is insulin the missing link? Cancer Causes Control. 1996;7:605-625.
8.            International Agency for Research on Cancer. Weight  control and Physical activity. Vol 6. Lyon: IARCPress; 2002.
9.            Bernstein L, Ross RK, Lobo RA, Hanisch R, Krailo MD, Henderson BE. The effects of moderate physical activity on menstrual cycle patterns in adolescence: implications for breast cancer prevention. Br J Cancer. Jun 1987;55(6):681-685.
10.          Bernstein L, Henderson BE, Hanisch R, Sullivan-Halley J, Ross RK. Physical exercise and reduced risk of breast cancer in young women. J Natl Cancer Inst. 1994;86:1403-1408.
11.          Tworoger SS, Missmer SA, Eliassen AH, Barbieri RL, Dowsett M, Hankinson SE. Physical activity and inactivity in relation to sex hormone, prolactin, and insulin-like growth factor concentrations in premenopausal women - exercise and premenopausal hormones. Cancer Causes Control. Sep 2007;18(7):743-752.
12.          NHLBI Obesity Initiative Expert Panel. Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults - The evidence report. Obesity Research. 1998;6(Suppl 2):51s-209s.
13.          Hu F, Sigal R, Rich-Edwards J, et al. Walking compared with vigorous physical activity and risk of type 2 diabetes in women: a prospective study. JAMA. 1999;282:1433-1439.
14.          Tamimi RM, Cox DG, Kraft P, et al. Common genetic variation in IGF1, IGFBP-1, and IGFBP-3 in relation to mammographic density: a cross-sectional study. Breast Cancer Res. 2007;9(1):R18.
15.          Boyd NF, Guo H, Martin LJ, et al. Mammographic density and the risk and detection of breast cancer. N Engl J Med. Jan 18 2007;356(3):227-236.
16.          Mathieu MC, Clark GM, Allred DC, Goldfine ID, Vigneri R. Insulin receptor expression and clinical outcome in node-negative breast cancer. Proc Assoc Am Physicians. Nov 1997;109(6):565-571.
17.          Frasca F, Pandini G, Sciacca L, et al. The role of insulin receptors and IGF-I receptors in cancer and other diseases. Arch Physiol Biochem. Feb 2008;114(1):23-37.
18.          Lanzino M, Garofalo C, Morelli C, et al. Insulin receptor substrate 1 modulates the transcriptional activity and the stability of androgen receptor in breast cancer cells. Breast Cancer Res Treat. Jun 4 2008.
19.          International Agency for Research on Cancer. Weight Control and Physical Activity. Vol 6. Lyon: International Agency for Research on Cancer; 2002.
20.          Calle EE, Kaaks R. Overweight, obesity and cancer: epidemiologic evidence and proposed mechanisms. Nat Rev Cancer. 2004;4:579-591.
21.          Chang SC, Ziegler RG, Dunn B, et al. Association of energy intake and energy balance with postmenopausal breast cancer in the prostate, lung, colorectal, and ovarian cancer screening trial. Cancer Epidemiol Biomarkers Prev. Feb 2006;15(2):334-341.
22.          Fair AM, Dai Q, Shu XO, et al. Energy balance, insulin resistance biomarkers, and breast cancer risk. Cancer Detect Prev. 2007;31(3):214-219.
23.          Fisher B, Costantino J, Wickerham D, et al. Tamoxifen for prevention of breast cancer: report of the National Surgical Adjuvant Breast and Bowel Project P-1 study. J Natl Cancer Inst. 1998;90:1371-1388.
24.          The Endogenous Hormones and Breast Cancer Collaborative Group. Endogenous sex hormones and breast cancer in postmenopausal women: reanalysis of nine prospective studies. J Natl Cancer Inst. 2002;94:606-616.
25.          Missmer SA, Eliassen AH, Barbieri RL, Hankinson SE. Endogenous estrogen, androgen, and progesterone concentrations and breast cancer risk among postmenopausal women. J Natl Cancer Inst. Dec 15 2004;96(24):1856-1865.
26.          Kannel WB, Dawber TR, Friedman GD, Glennon WE, McNamara PM. Risk Factors in Coronary Heart Disease. An Evaluation of Several Serum Lipids as Predictors of Coronary Heart Disease; the Framingham Study. Ann Intern Med. Nov 1964;61:888-899.
27.          Eliassen AH, Missmer SA, Tworoger SS, et al. Endogenous steroid hormone concentrations and risk of breast cancer among premenopausal women. J Natl Cancer Inst. Oct 4 2006;98(19):1406-1415.
28.          Clemons M, Goss P. Estrogen and the risk of breast cancer. N Engl J Med. Jan 25 2001;344(4):276-285.
29.          Bulun SE, Lin Z, Imir G, et al. Regulation of aromatase expression in estrogen-responsive breast and uterine disease: from bench to treatment. Pharmacol Rev. Sep 2005;57(3):359-383.
30.          Goss PE, Ingle JN, Martino S, et al. A randomized trial of letrozole in postmenopausal women after five years of tamoxifen therapy for early-stage breast cancer. N Engl J Med. Nov 6 2003;349(19):1793-1802.
31.          Haiman CA, Dossus L, Setiawan VW, et al. Genetic variation at the CYP19A1 locus predicts circulating estrogen levels but not breast cancer risk in postmenopausal women. Cancer Res. Mar 1 2007;67(5):1893-1897.
32.          Eliassen AH, Colditz G, Rosner B, Willett  W, Hankinson SE. Adult weight change and risk of postmenopausal breast cancer. JAMA. 2006;296:193-201.

Thursday, July 1, 2010

Does Sunscreen Prevent Skin Cancer?

As we turn to summer, cookouts, and more time in the sun, a burning question is whether sunscreen prevents skin cancer. Much media attention has focused on the slow progress made by the FDA to bring US regulations into line with other countries to gain up to date benefits of sunscreen formulation and consumer labeling (see story).  Sun exposure is the major cause of skin cancer, and sunscreen can help protect against sunburn, but can sunscreen prevent skin cancer? Put simply: is sunscreen an effective way to lower the risk of skin cancer?
With more than one million Americans diagnosed each year, skin cancer is not something to be taken lightly. Although it is not usually life threatening, even the least dangerous types of skin cancer require treatment and can be severely disfiguring. At its worst, skin cancer can be deadly, and the most dangerous form, malignant melanoma, will claim over 8,500 lives this year. The rate of this cancer is rising across all sectors of our population increasing the need for prevention strategies for this cancer. Clearly, there is a need for prevention, but it remains uncertain whether sunscreen will meet that need.
Several lines of evidence suggest that sunscreen may play a protective role with respect to skin cancer. The strongest available evidence that sunscreen use is an effective approach to prevention of skin cancer comes from a 4.5-year community-based randomized controlled trial among 1,621 adult residents of a subtropical Australian town. In comparison with people randomized to using sunscreen at their discretion if at all, people randomized to daily use of a broad-spectrum SPF15+ sunscreen showed a 40% reduction in squamous cell carcinoma tumors at the conclusion of the trial [1].
Despite this supportive evidence, epidemiologic results on sunscreen and skin cancer have been mixed. Some studies have suggested that sunscreen may protect against skin cancer, while others have shown just the opposite—that it can increase risk. Non-randomized or observational studies of sunscreen use and skin cancer are plagued by confounding: the driving forces behind sunscreen use also are directly related to skin cancer. For example, susceptibility to sunburn and high sun exposure cannot be separated.  A growing concern is that advice to use sunscreen may lead to longer sun exposure once “protection” is applied, undermining the benefit of sunscreen.
Given the current body of evidence on sunscreen and skin cancer, the International Agency for Research on Cancer [2] has recommended daily use of sunscreen with a sun protection factor (SPF) of 15 or higher for people who work outdoors or who enjoy regular outdoor recreation. However, sunscreen should not be used as the sole method of sun protection nor as a means for extending the amount of time spent in the sun. The best way for individuals to lower their risk of skin cancer is to reduce their sun exposure by combining all strategies:
  • Staying out of the sun between the peak burning hours of 10 a.m. and 4 p.m.;
  • Seeking shade or bringing it (for example, a beach umbrella or tent); and
  • Wearing hats and other protective clothing, like long-sleeve t-shirts and lightweight pants.

Does this approach work? The Centers for Disease Control Task Force on Community Preventive Services  concluded that school-based educational/policy interventions (for children) and recreational-based educational/policy interventions (for adults) are effective in reducing sun exposure [3]. Both types of interventions are well represented by the Australian SunSmart program, ongoing since 1982, (formerly Slip! Slop! Slap!) which aims at reducing UV exposure through access to shade and consistent use of protective clothing, hats, sunglasses, and sunscreen.  Examples of SunSmart programming include accreditation of schools that adhere to its policy and practice requirements and collaboration with governmental agencies to protect outdoor workers.  The program has changed attitudes regarding sun tanning, led to increases in protective behavior, decreased costs of sun protection gear, societal acceptance of more protective attire (including hats, sunglasses, and “neck to knee” swimsuits for children) and, most importantly, decreasing incidence rates of skin cancer [4]. Within Australia, that sun-protective behavior increased from 1987-2002 during which time the SunSmart program was active [5]. The evidence from Australia indicates that active prevention efforts including television advertising campaigns can be highly effective in improving the population wide sun-protective behaviours, resulting in falling age-specific incidence rates for melanoma, in younger birth cohorts [6].   

Building comprehensive approaches to reducing sun exposure, not just using sunscreen, is necessary to achieve our goals of reducing the burden of skin cancer. It is not too late to cover up when in the sun and enjoy the outdoors this summer.

Literature cited
1.            Green, A., et al., Daily sunscreen application and betacarotene supplementation in prevention of basal-cell and squamous-cell carcinomas of the skin: a randomised controlled trial. Lancet, 1999. 354(9180): p. 723-9.
2.            The International Agency for Research on Cancer Working Group on the Evaluation of Cancer-Preventive Agents, Sunscreens, in IARC Handbooks of Cancer Prevention. 2001, International Agency for Research on Cancer: Lyon, France.
3.            Saraiya, M., et al., Preventing skin cancer: findings of the Task Force on Community Preventive Services On reducing Exposure to Ultraviolet Light. MMWR Recomm Rep, 2003. 52(RR-15): p. 1-12.
4.            Montague, M., R. Borland, and C. Sinclair, Slip! Slop! Slap! and SunSmart, 1980-2000: Skin cancer control and 20 years of population-based campaigning. Health Educ Behav, 2001. 28(3): p. 290-305.
5.            Dobbinson, S.J., et al., Weekend sun protection and sunburn in Australia trends (1987-2002) and association with SunSmart television advertising. Am J Prev Med, 2008. 34(2): p. 94-101.
6.            Hill, D. and R. Marks, Health promotion programs for melanoma prevention: screw or spring? Arch Dermatol, 2008. 144(4): p. 538-40.