Indoor tanning drastically increases melanoma risk, and scientists have now mapped the sweeping DNA damage tanning beds inflict across nearly the entire skin surface — damage far beyond what sunlight causes.
- Researchers examined thousands of medical records to compare melanoma rates in people who used tanning beds and those who did not, then performed genomic analysis on 182 skin biopsies from both groups to track mutation patterns.
- People who used tanning beds showed nearly twice as many DNA mutations as individuals in the control group.
- These mutations were found not only on commonly exposed skin, but also in body areas that rarely see sunlight, revealing how far tanning bed damage can spread.
Indoor tanning, melanoma risk and DNA damage
Using tanning beds is linked to nearly a threefold increase in the risk of melanoma, and for the first time, researchers have shown how these devices create melanoma-related DNA damage across almost the entire surface of the skin, according to a new study led by Northwestern Medicine and the University of California, San Francisco.
Melanoma is the most lethal form of skin cancer and is responsible for about 11,000 deaths in the U.S. each year. For years, health experts have warned about the dangers of indoor tanning, yet the exact biological pathway connecting tanning beds to cancer had not been fully mapped. The indoor tanning industry, which has been experiencing a resurgence in popularity, has pointed to that gap in knowledge to claim that tanning beds are no more dangerous than natural sunlight.
The new research, the authors say, “irrefutably” counters those arguments by demonstrating that tanning beds, at the molecular level, change skin cells in ways that go far beyond the impact of everyday sun exposure.
“Even in normal skin from indoor tanning patients, areas where there are no moles, we found DNA changes that are precursor mutations that predispose to melanoma,” said study first author Dr. Pedram Gerami, professor of skin cancer research at Northwestern University Feinberg School of Medicine. “That has never been shown before.”
Melanoma survivors who previously used tanning beds and donated their skin biopsies for this work are available for interviews upon request.
The findings were published Dec. 12 in the journal Science Advances.
Clinical mystery in younger melanoma patients
Gerami, who also directs the melanoma program in dermatology at Northwestern, has treated people with melanoma for two decades. During that time, he began to notice a striking pattern: an unusually high number of women under age 50 who had experienced multiple melanomas and reported using tanning beds. He suspected that frequent indoor tanning was the shared factor tying these cases together.
To investigate, Gerami and his team designed the epidemiologic portion of the study. They analyzed medical records for about 3,000 people with a history of tanning bed use and compared them with roughly 3,000 age-matched individuals who had never used indoor tanning devices.
In this comparison, melanoma was diagnosed in 5.1% of people who used tanning beds, versus 2.1% of those who did not. Even after the researchers accounted for age, sex, history of sunburn, and family history of melanoma, indoor tanning was still associated with a 2.85-fold increase in melanoma risk.
The study also found that people who used tanning beds were more likely to develop melanoma on body areas that are usually shielded from the sun, such as the lower back and buttocks. These observations supported the idea that tanning beds may inflict more widespread DNA damage than ordinary sun exposure.
DNA sequencing reveals widespread mutations
To explore that possibility further, the scientists turned to advanced genomic tools. They used newer technologies to perform single-cell DNA sequencing on melanocytes (the pigment-producing skin cells where melanoma begins) from three different groups of skin donors.
The first group consisted of 11 patients from Gerami’s clinic who had long histories of indoor tanning. The second group included nine individuals who had never used tanning beds but were otherwise similar in age, sex and overall cancer risk. A third group of six cadaver donors provided additional skin samples to strengthen the control group.
In total, the team sequenced 182 individual melanocytes. They discovered that melanocytes from tanning bed users carried nearly twice as many genetic mutations as those from the control groups and were more likely to harbor mutations associated with melanoma. In people who tanned indoors, these mutations also showed up in areas of the body that typically stay covered and are not regularly exposed to the sun, reinforcing the conclusion that tanning beds cause a broad field of DNA damage.
“In outdoor sun exposure, maybe 20% of your skin gets the most damage,” Gerami said. “In tanning bed users, we saw those same dangerous mutations across almost the entire skin surface.”
Cancer survivor shares the toll of tanning beds
The study depended on the willingness of Gerami’s patients to donate skin biopsies. One participant, 49-year-old Heidi Tarr from the Chicago area, used tanning beds frequently as a teenager in high school — two to three sessions a week — because friends and celebrities at the time were also doing it and “it felt like that’s what made you beautiful.”
Years later, in her thirties and now a mother, she spotted a mole on her back and immediately feared it might be something serious. The spot turned out to be melanoma, leading to surgery, years of regular follow-up appointments and more than 15 additional biopsies as new moles appeared. “The biopsies can be painful, but the mental anxiety is worse,” she said. “You’re always waiting for the call that it’s melanoma again.”
After Gerami described the new research project, Tarr readily agreed to provide additional biopsies. “I value science, and I wanted to help,” she said. “If what happened to my skin can help others understand the real risks of tanning beds, then it matters.”
‘Wronged by the industry’
Seeing the genetic data and the clinical trends together convinced Gerami that stronger safeguards are needed. “At the very least, indoor tanning should be illegal for minors,” he said.
“Most of my patients started tanning when they were young, vulnerable and didn’t have the same level of knowledge and education they have as adults,” he said. “They feel wronged by the industry and regret the mistakes of their youth.”
Gerami also believes tanning beds should carry warnings comparable to those on cigarette packages. “When you buy a pack of cigarettes, it says this may result in lung cancer,” he said. “We should have a similar campaign with tanning bed usage. The World Health Organization has deemed tanning beds to be the same level of carcinogen as smoking and asbestos. It’s a class one carcinogen.”
He recommends that anyone who frequently used tanning beds earlier in life schedule a total-body skin examination with a dermatologist and talk with their doctor about whether they should have ongoing, routine skin checks.
Gerami is a member of the Robert H. Lurie Comprehensive Cancer Center of Northwestern University.
The study, titled “Molecular effects of indoor tanning,” was funded by the National Institutes of Health (grants R01 CA265786 and AR080626), the Department of Defense Melanoma Research Program (grant ME210014), the Melanoma Research Alliance Team Science Award, the Melanoma Research Alliance Dermatology Fellows Award, the LEO Foundation Region Americas Award, Cancer Center Support (grant P30CA082103), the IDP Foundation Award and the Greg and Anna Brown Family Foundation Award.
