Monday, January 12, 2015

Preventing Skin Cancer: Tanning Beds Still Alluring, Still Very Risky

Photo: Flickr/whatshername, Creative Commons Lic.
There was a nice piece in the New York Times this weekend on the risks of indoor tanning, particularly in youth. Focussing on the personal experiences of a handful of young women and their  parents, it does a very good job highlighting the well-established risks of skin cancer and deadly melanoma, the continued allure of tanning, and some promising advances in tanning salon regulation and rates of tanning by youth.

We've written a number of posts over the years here on Cancer New in Context (see below) about the dangers of tanning beds and the need for better policies to curb their use and protect youth. So, it's good to see the topic continuing to gain traction both in terms of awareness and in the willingness of state and federal government to take important tax and regulatory action to try to maintain the recent downward trend in tanning bed use.

In many ways, it's similar to the concerted efforts that have helped curb tobacco use over the past 50 years, a similarity not lost on 22 year-old Westfield State University student, Elizabeth LaBak, who was highlighted in the Times article:
“The tanning thing is like the smoking thing,” she said. “Everyone used to smoke. And then they said, ‘You’ll die of lung cancer.’ That’s what’s happening to tanning.”
As this quote sums up,  there's a lot more than "bad luck" involved when it comes to developing skin cancer risk.  In fact, skin cancer - including deadly melanoma - is a prime example of the importance of prevention.  Protecting yourself from the sun and staying away from indoor tanning can significantly lower risk.

Of course, attitudes to tan skin and tanning can be slow-to-change, especially since they are so intertwined with other complex issues of appearance and body image. But the multi-faceted approaches that have been used so far have a great chance of success.  For real progress, though, they need to be extended to more states and expanded in approach.  The blistering truth is that we still have a long way to go.

Other Cancer News in Context articles on tanning and skin cancer risk:
New Study: Tanning Bed Use Brings Skin Cancer RisksJun 25, 2014
A new study out this week further confirms the dangers of indoor tanning, finding that use of tanning beds and other UV tanning devices is strongly linked to developing skin cancer early in life. Published early online in the ... 
Tanning Industry Fights the Blistering Truth: That Tanning Beds Raise the Risk of Melanoma and Other Skin CancersJan 07, 2013
A recent article in MedPage Today highlighted the birth of a new tanning salon industry-sponsored group that has the sole intent of refuting well-established and peer-reviewed science showing the dangers of tanning bed use ... 
With Spring in the Air, New Sun-Safe, UV-Safe Recommendations from the American Academy of PediatricsMar 29, 2011
The statement, published in the journal Pediatrics (link), refreshes and reinforces what many of us know - that unprotected sun exposure and tanning bed use are unhealthy activities for everyone, but particularly so for youth. 
Mother/Daughter Tanning and the Dual Nature of Family HistoryDec 29, 2010
We've dedicated a number of posts over the past year on the policy and health pitfalls of indoor tanning - from the potential benefits of the "tanning tax" (post) to surprisingly high rates of tanning by some youth (post). 
Tanning Beds, Addiction, and TaxesApr 20, 2010
A new study in this month's Archives of Dermatology suggests that indoor tanning can be addicting in young adults (study) (1). While the study was relatively small, with just over 400 participants surveyed, the results seem to ... 
More Blistering Truths About Tanning Bed Use By YouthApr 05, 2010
A new study published online last week in the British Medical Journal on tanning bed use by youth in the United Kingdom has raised concerns well beyond its shores (full study) (1). The study surveyed over 9,000 children ...

Thursday, January 8, 2015

Setting the Record Straight on Cancer Prevention: Lifestyle Trumps "Bad Luck"

While the paper by Tomasetti and Vogelstein is certainly intriguing and will help guide future research on targeting prevention and early detection efforts, it is still a preliminary finding and does not reverse the long-term conclusion that is supported by decades of well-designed research in people:  that cancer is largely preventable.
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It's been hard to avoid the headlines this past week touting the conclusions of a new study in the journal Science that cancer is a disease largely caused by "bad luck."  Some of these headlines have been sensationalized; some have been more measured.  Together, they've seemed nearly ubiquitous.  And in some ways that's been positive, demonstrating that cancer - and its causes and prevention - remain an important topic to both the public and the media.

Unfortunately, the conclusions of the paper - and the subsequent coverage they've received - seem to reach well beyond what the actually findings of the study support, and in doing so, have incorrectly called into question what decades of overwhelming evidence shows:  that over half of all cancers - and up to three quarters of some cancers - could be prevented by regular screening and healthy lifestyle choices.

The new study by Johns Hopkins researchers Cristian Tomasetti and Bert Vogelstein gathered data on the number of stem cell divisions that occur in various tissues in the body and compared these data to annual incidence rates of cancers in those tissues.  Stem cells divide to replace cells in tissue that die or are lost.  This maintains the tissue.  Some tissues need a lot of cell divisions for maintenance.  Others need less.  When cells divide, the DNA in cells also replicate and divide, opening up the chance for random mutations that could eventually lead to cancer.

The researchers found a strong correlation between tissues' number of stem cell divisions and cancer in those tissues, attributing 65% of cancers to these divisions, and the random DNA mutations that can occur with them.

While the study is well-designed and executed, it also has some key limitations that don't fully support its overarching conclusions.

First, the study was not done directly in humans.  It correlated data on cancer rates with tissue cell division data generated from cell analyses done in labs.  It is essentially a laboratory-based study, and lab studies in general are fantastic ways to generate hypotheses on cancer causes but bad ways to generate conclusive evidence on actual causes of cancer in humans.  The research world is littered with promising findings in petri dishes and mice that were never proved in actual people.

Second, many of the cancers included in the study are those already known to have few, if any, known lifestyle risk factors.  And while the study included two common preventable cancers, lung and colorectal, it also did not include two other major cancers with key lifestyle factors - breast and prostate cancer.  Together, lung, colorectal, breast, and prostate cancers account for approximately half of newly diagnosed cancers in the United States, a number much higher than the   other serious cancers included in the study.  The study itself even showed that colorectal cancers and lung cancers (in smokers) were less due to "bad luck" mutations than most others in the study. Other analyses based on long-term studies in humans have found that up to 75 percent of lung and colon cancers could be prevented, as well as at least half of breast cancers.

Finally, simply because there is a correlation between stem cell division and rates of cancer does not mean that random DNA mutations are the precipitating cause of cancer.  Multiple cell divisions could accelerate the cancer-causing effects of lifestyle factors. And many lifestyle factors  - from obesity to smoking - are thought to increase the risk of cancer by fostering cell division and DNA changes that begin the cascade to cancer.  So what is described as random "bad luck" may actually have its genesis in lifestyle choices.

While the paper by Tomasetti and Vogelstein is certainly intriguing and will help guide future research on targeting prevention and early detection efforts, it is still a preliminary finding and does not reverse the long-term conclusion that is supported by decades of well-designed research in people:  that cancer is largely preventable.  In our own 2012 paper that also appeared in a Science publication - Science Translational Medicine - we conclude that over half of the 572,000 deaths from cancer in the United States in 2011 were caused by key modifiable risk factors, such as smoking, obesity, and lack of physical activity.

Of course, "bad luck" plays a role in any cancer - any disease, for that matter.  We know people who smoke and drink and weigh more than they should who live until their 90s, and we know the healthiest people in the world who are struck down by disease early in life.  Healthy choices, though, can greatly increase our odds of living longer and healthier lives.  It's no guarantee, but it helps to stack the deck in our favor.

For more on the preventability of cancer, see our page: Preventing Cancer - Today

Monday, January 5, 2015

New Study Shows Being Sedentary is Bad for Physical and Fiscal Health

Creative Commons photo (cropped): Flickr/hjl
There is no magic bullet that will guarantee good health.  That's just an unfortunate fact of life.  But there is something that can help stave off heart disease, diabetes, cancer, osteoporosis, and depression, while also helping us maintain a higher quality of life as we get older.  And it's largely free and accessible to just about everyone: physical activity.

We've written a lot over the years here on Cancer News in Context about the benefits of being active, but not very much about the economic costs of being inactive - both for individuals and for the nation as a whole.  Yet, with the nation growing older and health care costs continuing to accelerate, there's a fantastic need to highlight effective and simple approaches to address such issues. And a new study out this month in Progress in Cardiovascular Diseases highlights just how important regular physical activity is to the physical and economic health of the nation.