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Tanning News > Minnesota Tanning Study Flawed


3 Mar 2011

2010-05-26 Debate copyA University of Minnesota advocacy group appears to have “reverse-engineered” a study to bolster its own pre-existing anti-indoor tanning crusade, failing to properly cite the significance of conflicting data within its own paper, downplaying confounding data that opposed its conclusions and failing to disclose the conflict-of-interest of its own anti-tanning advocacy efforts.

“This study was designed and executed by an advocate, not a neutral party, and the advocate failed to properly disclose that she is not a neutral party,” said Joseph Levy, vice president of International Smart Tan Network, the educational institute for the North American indoor tanning community. “That conflict of interest clouds some of the irregularities reported in the paper.”

Dr. DeAnn Lazovich, lead author of “Indoor Tanning and Risk of Melanoma: A Case-Control Study in a Highly Exposed Population,” published in 2010 in the Journal of the American Association for Cancer Research, failed to disclose in the paper that she is part of a University of Minnesota group that initiated programs to discourage indoor tanning use three years before designing and engaging in data collection for this study. Those interactions may themselves have tainted subjects and controls used in the study.

Most epidemiologic papers on this topic (18 of 23 ever conducted) show no statistically significant association between indoor tanning usage and melanoma. The ones that have shown an association have failed to accurately account for confounding variables such as genetic predisposition, home tanning unit usage or outdoor sun exposure habits.

The International Smart Tan Network finds serious flaws with the study. Specifically:

1.  The authors downplayed conflicting evidence. The study showed that individuals who got the most outdoor sun exposure in their lives had a 15 percent lower risk of melanoma when compared to those who got less sun — a conflicting result from their main thesis. The paper is actually the latest in a line of studies showing that people who get the most UV exposure outdoors actually are less likely to contract the disease.”Despite what the authors in this paper set out to prove, the fact remains that whatever relationship UV exposure has with melanoma is still not understood because paper after paper, including this one, continue to show that people who get more sun exposure have fewer melanomas,” said Dr. William Grant, founder of the independent Sunlight, Nutrition and Health Research Center (SUNARC). Grant, an independent advocate for UV exposure as the natural and intended source of vitamin D, published a peer-reviewed meta-analysis this year showing that indoor tanning is not a risk factor for melanoma in individuals with skin that can tan, with UV-related risk isolated only in the fairest-skinned “Skin Type I” subjects who have tanned in the past in Europe, but who are screened in North American tanning facilities.That appears to be why the University of Minnesota group chose the ethnically homogenous Minnesota, whose population is 80 percent fair-skinned Northern European heritage and not representative of the U.S. population.

2.  In suggesting that tanners double their risk of melanoma, the authors mention only relative risk figures in the paper, ignoring that more telling figure that the absolute risk of melanoma is quite low for both tanners and non-tanners. The largest study to date shows that both indoor tanners and non-tanners have less than a 0.3 percent risk of contracting melanoma and most studies show no statistically significant difference between the two groups. The misleading nature of “relative risk” figures in melanoma data was the topic of an article published by The Association of Health Care Journalists May 7 by Dr. Ivan Oransky, a Reuters Health editor.Oransky quotes Dr. Lisa Schwartz, a general internist at Veterans Affairs Medical Center in White River Junction, Vt., and co-author of “Know Your Chances,” a book that explains health statistics to consumers.

“Melanoma is pretty rare and almost all the time, the way to make it look scarier is to present the relative change, the 75 percent increase, rather than to point out that it is still really rare,” Schwartz told The Wilmington News Journal’s Hiran Ratnayake, who interviewed Schwartz in a recent story on melanoma and indoor tanning.

3.  The Minnesota study also reported that high lifetime chemical sunscreen usage increased melanoma risk by 31 percent — a finding the authors downplay but which comes on the heels of an Environmental Working Group report this week showing that sunscreen usage may be contributing to cancer risk.

4.  There are statistical irregularities in the Minnesota paper. While only an estimated 10 percent of the adult population in Minnesota utilizes indoor tanning facilities, 51 percent of the paper’s “randomly selected” control group had used tanning equipment — a statistical difference so unlikely as to almost be impossible.

5.  The authors admit that researchers and doctors had undocumented inappropriate interactions with the case group. And while they attempt to explain this, they don’t disclose that the study’s University of Minnesota designers had engaged in a multi-year campaign to discourage indoor tanning usage for years prior to conducting this study — a conflict-of-interest that likely created bias in doctors, cases and all doctor-case interactions in the study.Because the results of this study are statistical outliers in the sum of work on this topic, the potential for bias in this study model cannot be discounted, particularly because the authors failed to disclose their anti-tanning advocacy conflict-of-interest.

6.  The University of Minnesota group engaged in deceptive practices in 2001 when, using a National Cancer Institute grant, it developed a bogus indoor tanning training program in order to obtain data from indoor tanning facilities for future studies. According to reports, the Minnesota group told salons they were attempting to help operators lower their risks, but the University of Minnesota refers to the same grant on its web site as an effort to reduce indoor tanning usage.

7.  The authors understate the nature of previous research on this topic, suggesting that, “With at least 29 reports to date, past history of indoor tanning has been only weakly associated with melanoma.” In fact, 18 of 22 previous studies show no statistically significant association.

8. The authors mis-state the nature of a 2009 IARC report on indoor tanning and melanoma — a 400-word article in which IARC classified UV light from indoor tanning units as carcinogenic. In fact, the U.S. government has classified UV light from indoor tanning as carcinogenic since the publication of The 9th Report on Carcinogens 2000. But, more accurately, such a classification has no dose attached to it. According to that report, “The Report does not present quantitative assessments of carcinogenic risk. Listing of substances in the Report, therefore, does not establish that such substances present carcinogenic risks to individuals in their daily lives.”

“Saying that UV is dangerous and should be avoided without mentioning that critical caveat is like saying that water is dangerous because it causes drowning, and therefore humans should avoid all water,” Levy said. “It’s a misrepresentation.” Smart Tan believes a balanced picture about UV exposure — which vitamin D research in the past two years has proven is natural and intended — will benefit consumers.

“We are happy to participate in that discussion on a high level. While the professional indoor tanning community continues to responsibly warn people about the risks of sunburn and overexposure, groups who benefit financially from overstating the risks of regular non-burning UV exposure continue to misrepresent data to the detriment of the consumer,” Levy continued, “We think the promotion of this study has more to do with justifying a dinosaur mentality about UV light in an era when vitamin D research is proving that decades of overzealous sun avoidance may have skyrocketed SPF sales, but has caused epidemic-level vitamin D deficiency and great confusion in the population.”

 

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