Studies validate conventional wisdom to lower melanoma risk

Issue: July 25, 2011

New data and a review of recent studies on the use of sunscreen, as well as the increased risk conferred by the use of indoor tanning, validate conventional wisdom regarding melanoma risk reduction.

The first randomized controlled trial to show that sunscreen can prevent melanoma appeared earlier this year in the Journal of Clinical Oncology, according to Martin A. Weinstock, MD, PhD, professor of dermatology and epidemiology at Brown University, R.I., who presented the review. This study, by Green and colleagues, showed the incidence of melanoma was nearly half in study participants who used sunscreen compared with those who did not.

In the study, of 812 participants who received sunscreen, 11 developed melanoma. Of 809 participants who did not receive sunscreen, 22 developed melanoma (HR=0.50; 95% CI, 0.25-1.02). Participants were followed for more than a decade in the Australian study, Weinstock said. No subgroups of participants were identified at being at particular risk.

“This is one of the reasons why the FDA now allows sunscreens to say that they are a skin cancer preventive,” said Weinstock, who is chair of the American Cancer Society Skin Cancer Advisory Committee. Up until recently, sunscreen labeling did not allow the claim to be made.

As for indoor tanning, within the past year, the Norwegian-Swedish Women’s Lifestyle and Health Cohort Study, a population-based study of 106,366 women followed for 14 years, revealed an association between indoor tanning and subsequent risk for melanoma. The study by Veierod and colleagues was published in January 2010 in Cancer Epidemiology Biomarkers and Prevention. “The most important number is the 30% increased risk for ever use below the age of 40 for indoor tanning and more than doubling of risk for more intensive use, which they defined as use of at least once per month in 2 of the 3 decades between the ages of 10 and 40,” Weinstock said.

A Minnesota case-control study, by Lavovich and colleagues in Cancer Epidemiology Biomarkers and Prevention in May 2010, corrected for a variety of deficiencies present in prior case control studies in melanoma, according to Weinstock. That study found that indoor tanning further increased risk for melanoma between the ages of 25 and 59 years. Participants included 1,167 cases from a statewide registry and 1,101 controls. The adjusted OR was 1.74 (95% CI, 1.4-2.1) for ever vs. never use. There was a dose response relationship according to hours spent tanning, the number of sessions and the number of years of indoor tanning within each age category of age, he said.

The Australian Melanoma Family population-based study by Cust and colleagues in the International Journal of Cancer, July 2010, focused on a younger group of patients who had melanoma prior to age 40 years. The OR in that study was 1.41 (95% CI, 1.01-1.96), “which is over a 40% increased risk associated with an ever use of indoor tanning,” Weinstock said. “If there were greater than 10 lifetime sessions, that more than doubled the risk.”

“There was over a six fold risk estimate for melanoma occurring under the age of 30 [years] for people who used indoor tanning,” Weinstock said. “They estimated over three-quarters of melanomas in Australia that were diagnosed before the age of 30 were attributable to indoor tanning use.”

The Icelandic Descriptive Epidemiologic study published by Héry and colleagues in the American Journal of Epidemiology, September 2010, traced the association between indoor tanning salons and their subsequent closures with cases of melanoma. According to Weinstock, there were only three tanning salons Reykjavik in 1979. By 1988, there were 56 salons with 207 sunbeds. A subsequent sharp uptick in melanoma risk occurred, and by 2004, non-profit and government campaigns were under way to discourage the use of indoor tanning, which resulted in a more than 50% decrease in the number of indoor tanning facilities.

“In the under-50 group, the major users of indoor tanning, you’ll see a gradual increase in melanoma risk, up through the early 1990s, and then in the 1990s, there was a huge jump, over 15% a year, in the incidence of melanoma. But then in the 2000s, there was a sharp decrease of more than 9% a year in the diagnosis of melanoma. That corresponds roughly to the prevalence and use of indoor tanning in that country,” he said.

Weinstock spoke about the Indoor Tanning Association campaign that appeared in The New York Times in the past year, which, he said, decried the melanoma “hype.” The FTC took action against the group, which has constrained it from promoting the health benefits of indoor tanning. “That’s going to be a major asset to public health efforts to control melanoma risk,” he said.

In response to the increased rates of melanoma, Brazil banned the use of indoor tanning for cosmetic purposes in 2009. Tanning regulations are widespread in the US, but are ineffectual, Weinstock said. He added that indoor tanning should be banned for children younger than the age of 18 years, as it is in other countries around the world.

Disclosure: Dr. Weinstock has served as a consultant for Merck.

The 2012 HemOnc Today Melanoma and Cutaneous Malignancies Meeting will be held April 13-14 at the Grand Hyatt, New York, NY. Learn more at HemOncToday.com/melanoma.