New research shows tanning beds use nearly triples melanoma risk and causes more extensive DNA mutations than natural sunlight
Tanning bed use is linked to nearly a threefold increase in melanoma risk and causes widespread DNA damage across the skin, according to a major new study led by Northwestern Medicine and the University of California, San Francisco.
By analysing thousands of medical records and sequencing skin biopsies, researchers found that tanning bed users carried twice the mutation burden of non-users, with cancer-linked mutations appearing even in areas rarely exposed to sunlight. The findings challenge long-standing claims from the indoor tanning industry and shed new light on how tanning beds drive the deadliest form of skin cancer.
The findings are published in Science Advances.
Tanning beds mutate skin cells beyond the capabilities on natural sunlight
Melanoma is the deadliest form of skin cancer, killing thousands. The use of sun beds is discouraged because of strong links to other skin cancers. However, despite research, the indoor tanning industry continues to claim that tanning beds are no more harmful than sunlight.
The new study “irrefutably” challenges this claim by showing how tanning beds, at a molecular level, mutate skin cells beyond the reach of ordinary sunlight. The researchers used donated biopsies from melanoma survivors with histories of tanning bed use.
“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.”
Comparing the medical records of tanning bed users and age-matched controls
The researchers collated medical records for about 3,000 tanning bed users and 3,000 age-matched controls without a history of indoor tanning. They found melanoma was diagnosed in 5.1% of tanning bed users compared with 2.1% of non-users. After adjusting for age, sex, sunburn history, and family history, tanning bed use remained associated with a 2.85-fold increase in melanoma risk.
Tanning bed users were also more likely to develop melanoma on sun-shielded body sites, such as the lower back and buttocks. These findings support the idea that tanning beds may cause broader DNA injury than sun exposure.
To test that hypothesis, the researchers used new genomic technologies to perform single-cell DNA sequencing on melanocytes from three skin donor groups.
The first group included 11 patients with long histories of indoor tanning. The second group included 9 patients who had never used tanning beds and were matched for age, sex, and cancer risk profiles. The third group was six cadaver donors who supplied additional skin tissue to complete the control samples.
The researchers sequenced 182 individual melanocytes and found skin cells from tanning bed users carried nearly twice as many mutations as those from controls and were more likely to contain melanoma-linked mutations. In indoor tanners, the mutations also appeared in body areas that usually remain protected from the sun, confirming that tanning beds create a broader field of DNA injury.
“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.”
After considering the biological and clinical evidence, they called for policy reform, specifically stating that indoor tanning should be made illegal for minors to reduce youth exposure to this cancer risk.
“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 further recommended that tanning beds display explicit warnings about cancer risk, similar to those found on cigarette packaging. He argued that public health campaigns should make clear that tanning beds are classified by the World Health Organization as a class one carcinogen, equivalent to smoking and asbestos, to ensure consumers are fully informed of the dangers.
