Indoor tanning may significantly increase the risk of developing early-onset skin cancer, a new Yale study has found.

A team of researchers from the Yale School of Public Health reported that individuals who used tanning beds at least once are at a 69 percent greater risk of developing basal cell carcinoma, the most common form of skin cancer, before the age of 40. The study, published in the December issue of the Journal of the American Academy of Dermatology, found skin cancer risk was correlated with frequency of tanning, and the effect was especially pronounced for women. Experts interviewed say that the study’s findings are unsurprising, given past research on the dangers of indoor tanning, but will still help raise public awareness of the issue.

“This study, in combination with the research done on melanoma, reinforces how dangerous indoor tanning can be,” said Leah Ferucci GRD ’09, a postdoctoral fellow at the School of Public Health and lead author of the study. “If we prevent the initiation of indoor tanning, we could prevent many, many cases of skin cancer.”

The researchers interviewed 376 community members under the age of 40 with a history of basal cell carcinoma and 390 with no history of the disease. Each participant provided information on how frequently they visited tanning salons, as well as their age of initiation, duration, and history of burns while tanning.

An increase of any of these factors was associated with elevated risk of developing BCC. For example, participants who had reported visiting tanning beds for at least six years were twice as likely to develop the disease as those who had never tanned. Additionally, indoor tanning was associated with lesions that developed in areas that sunlight would not normally reach, such as the limbs and trunk area, while naturally occuring lesions are generally found on the face or neck.

The cancer manifests itself as mole-sized skin lesions that are rarely fatal but costly to remove. Treatment costs can often be staggering, as people diagnosed with the disease often develop more than one lesion, Ferucci said that one-quarter of early-onset BCC could be prevented if the threat of indoor tanning was eliminated.

Women in the study were much more likely to report having visited tanning salons, and they were found to be twice as likely to develop BCC after a single indoor tanning session. A strong association was not found in men, though this does not necessarily suggest that men are immune to tanning-related skin cancer, as the population of tanning males was too low to find a significant result, Ferucci said.

Alan Fleischer, professor of dermatology at the Wake Forest Baptist Health Center, said that although the results did not shed new light on the issue, they can nevertheless help focus the public’s attention on the dangers of indoor tanning.

“Knowledge by itself is generally ineffective in changing behavior, but knowledge is required to effect change,” Fleischer said.

Recent data show that instances of BCC are on the rise, with 1 million cases reported in the United States each year — a 300 percent increase since 1994, according to a recent article in the journal Archives of Dermatology.

The public’s perception of the desirability and safety of tanning — be it indoors or outdoors — must be changed in order to decrease future instances of skin cancer, Fleischer said. He explained that too many Americans wrongly believe that burns are dangerous and that burn-free tanning carries no risks. In fact, he said, all ultraviolet light exposure carries a risk of cancer.

Tanning salons are especially important to public health experts because people are more likely to make indoor tanning a part of their routine than outdoor tanning, said Bryon Adinoff, professor of psychiatry at the University of Texas Southwestern Medical Center and Veteran’s Association North Texas Health Care System. For example, approximately 30 million Americans tan indoors each year, but on any given day, 1 million will visit a tanning salon.

The desire to frequent tanning beds may be driven by motives other than the appeal of a tanned complexion, Adinoff said, because ultraviolet light rays have the potential to become addictive. Adinoff’s research shows that exposure to the light activates areas in the brain associated with drug addiction.

“It would explain why people continue to frequent indoor tanning salons despite known risks such as skin cancer,” Adinoff said.

Seventy percent of early-onset basal cell carcinomas occur in females.