The study is the largest of its kind to examine whether indoor tanning causes skin cancer, and it comes as federal regulators are considering new rules designed to limit the use of commercial tanning by teens.
Compared to people who had never used a tanning bed, indoor tanners had a 74% increased risk for melanoma.
People who spent more than 50 hours tanning indoors had a threefold increase in risk, compared to people who never used a tanning bed, after adjusting for known risk factors for the deadly skin cancer.
The risk was four times higher among frequent users of high-pressure tanning beds, which emit mostly UVA radiation.
Researcher DeAnn Lazovich, PhD, of the University of Minnesota says the study was designed to address the limitations of past research, which have allowed the tanning industry to continue to deny that indoor tanning causes skin cancer.
“Our data would suggest that there is no safe tanning device,” she tells WebMD.
Melanoma, Indoor Tanning Increasing
The American Cancer Society predicted that in 2009, nearly 70,000 Americans would be diagnosed with melanoma and more than 8,500 people would die of the disease.
Melanoma is one of the fastest-growing cancers among whites, increasing by about 2% a year between 1997 and 2006.
During this time, the popularity of indoor tanning exploded, especially among women under age 30. Only a few tanning salons existed in the United States in the early 1980s. Today, by one industry estimate, more than 30 million Americans use commercial tanning beds each year.
Allan Halpern, MD, who is chief of dermatology at New York’s Memorial Sloan-Kettering Cancer Center, says the new study suggests a clear link between the increased popularity of indoor tanning and the rise in melanoma.
“One of the challenges in these studies has been that people who use tanning beds also tend to tan in the sun,” he tells WebMD. “That has allowed the industry to claim that indoor tanning isn’t to blame.”
Also, most previous studies did not distinguish between high-speed machines, which emit some UVB rays, and high-pressure machines, which emit almost exclusively UVA rays.
The latest study included nearly 1,200 melanoma patients and a similar number of age- and gender-matched people in a control group. Using questionnaires and telephone interviews, the researchers determined that 63% of the melanoma patients in the study had used a commercial tanning device at least once, compared to 51% of the people without cancer.
Among the other major findings:
- Melanoma risk increased with exposure, measured by total hours of indoor tanning, the number of individual sessions, or years of exposure.
- The increase in risk was seen for both high-speed and high-pressure machines, suggesting that no type of tanning device could be considered safe.
- Burns from indoor tanning were commonly reported.
- The strongest association was seen for melanomas originating on the trunk, which, in women at least, is an area of the body generally exposed to UV rays only during tanning.
The research showed no specific increase in melanoma risk associated with tanning bed use at a young age, but a clear association was seen for increased exposure over time.
The study appears in the June issue of the journal Cancer Epidemiology, Biomarkers & Prevention.
“Overall exposure was the important thing,” Lazovich says. “Melanoma is the second most common cancer among young women. Young women are particularly vulnerable because they are the most likely to use these devices.”
Tanning Industry Responds
In response to the study, a tanning industry spokesman said the findings are misleading because the researchers did not distinguish between people with major risk factors for melanoma and the general population.
Melanoma patients in the study were five times as likely as non-patients to have very fair skin and nearly 14 times more likely to have many moles.
John Overstreet of the Indoor Tanning Association tells WebMD that the group’s own scientific analysis of the findings suggests that when high-risk groups are removed, indoor tanning may actually lower melanoma risk.
Overstreet also said indoor tanning may protect against cancer by increasing vitamin D, which is produced in the body in response to UV exposure.
Vitamin D researcher Michael Holick, MD, tells WebMD that although indoor tanning may boost vitamin D levels, he does not recommend it.
“I have never advocated tanning,” he says. “What I have said is that people who want to do it using tanning beds to increase their vitamin D in the winter should do it responsibly. That means protecting your face and staying in for 50% of the time recommended for tanning.”
Feds May Soon Restrict Indoor Tanning
Last year, the World Health Organization’s International Agency for Research on Cancer (IARC) weighed in, concluding that indoor tanning does cause melanoma.
In March, an FDA panel met to consider regulatory changes that could restrict access to tanning salons.
Although an outright ban is unlikely, many believe the group will require minors to have their parents' permission if they want to use commercial tanning devices.