TUESDAY, Feb. 5, 2002 (HealthDayNews) -- If you seek the perfect indoor tan this winter, you may put yourself in jeopardy of developing common skin cancers, a new study says.
Ultraviolet (UV) light from the sun is the leading cause of skin cancers, including melanoma, the most deadly form of the condition. In addition, studies have suggested that tanning beds may also trigger the disease. But the latest work is the first to link the devices to two other forms of skin tumors, squamous cell and basal cell carcinomas, which together account for more than 1 million cases a year, according to the Skin Cancer Foundation. The study appears in tomorrow's issue of the Journal of the National Cancer Institute.
Margaret Karagas, lead author and an epidemiologist at Dartmouth Medical School, says people -- and especially teen-agers -- "need to be informed of their potential risk of skin cancer" from using tanning beds. Karagas and her colleagues suggest steps to protect the public may be warranted, such as laws keeping minors away from tanning beds or forcing parents to sign a consent form.
An estimated 28 million Americans use tanning beds each year, according to the Indoor Tanning Association. Studies have shown that roughly half of high school-aged girls report visiting tanning booths at least four times a year.
The National Institute of Environmental Health Sciences in 2000 classified both UVA and UVB rays as likely carcinogens, and said it didn't know whether one was more dangerous than the other. Early tanning devices cranked out UVB rays, but the newer models generate more UVA radiation.
The American Academy of Dermatology opposes indoor tanning, except for medical uses. In the absence of a ban on the products, the skin group says operators should post clear warnings about risk of skin cancer, patrons should sign statements to that effect, and minors shouldn't be allowed to use tanning beds without written permission from a parent or guardian.
The latest study was based on interviews with more than 1,400 New Hampshire residents, aged 25 to 74. Of those, 603 had been diagnosed with basal cell carcinomas (the most common form of all cancers), 293 had developed squamous cell tumors, and the rest were skin cancer-free at the time of the survey.
After factoring in age, sex, number of severe sunburns and outdoor sunbathing habits, tanning lamps were associated with a 2.5-fold higher risk of squamous cell carcinomas, and 1.5-fold greater odds of basal cell tumors, the researchers say. Each decade a person said they'd been using a tanning device raised their risk of the two cancers 20 percent and 10 percent, respectively, although the trend here was statistically shaky.
"What it appears in our data is that the age of exposure seemed to have a stronger effect than the other tanning lamp factors" on the risk of developing skin tumors, Karagas says. That makes sense, she adds, because other studies have found that early exposures to both natural and artificial UV rays increase the odds of melanoma. Other studies have shown that people get nearly four-fifths of their lifetime exposure to sunlight by the time they turn 18.
However, Joe Levy, a spokesman for the Indoor Tanning Association, says the study is well short of conclusive. More than half the subjects with skin cancer reported first using a tanning machine before 1975. That was at least a decade before regulation of the technology began and there was a good understanding of proper exposure to artificial ultraviolet rays, he says.
Levy also says people with skin cancers have been known to overstate their history of sunburns and their use of tanning beds, making surveys of this group potentially unreliable.
Karagas admits recall might have biased her results. However, she says, that's unlikely given the size of the increased risks of tumors associated with the two forms of cancer.
Dr. Brett Coldiron, a dermatologist at the University of Cincinnati, says the connection between tanning and tumors is "a no-brainer" and that "there's no way that the tanning beds don't cause skin cancer."
Coldiron, who acknowledges he's opposed to the devices, says proving a direct connection between environmental exposure and a disease is difficult. Many people develop skin lesions after relatively minimal sun exposure, for example, and few never spend any time in the sun.
"You're never going to find a smoking gun," he says.
What To Do
To learn more about skin cancer, try MEDLINEplus. You can also learn more about the disease by visiting the Centers for Disease Control and Prevention or the American Academy of Dermatology.
For more on tanning beds from the industry's perspective, try the International Smart Tan Network.
