Indoor tanning is associated with a higher risk of developing the deadly skin cancer melanoma at younger ages, and a recent study suggests the ultraviolet (UV) light in tanning beds may be triggering genetic mutations that can lead to skin malignancies.
Researchers examined data on 114 melanoma patients who had a history of indoor tanning and 222 melanoma patients who did not. After accounting for several factors that can impact melanoma risk - like gender, skin type, hair and eye color, sun exposure, and family history - researchers estimated that melanoma developed about a decade earlier when patients had a history of indoor tanning.
Genetic mutations linked to melanoma were also more common among indoor tanners, occurring in 43 per cent of patients in this group compared with 28 per cent of cases in people without a history of indoor tanning.
"No amount of indoor tanning is safe," said lead study author Dr Toni Burbidge of the University of Calgary Cumming School of Medicine.
"Many of our patients expressed the sentiment that they had been using indoor tanning as a way to develop a `base tan' to avoid burning when exposed to the sun outdoors," Burbidge said by email.
"Unfortunately, they may have added to their cumulative UV damage, resulting in an earlier diagnosis of melanoma than the patients who had never used indoor tanning."
High levels of UV light in tanning beds are absorbed by skin cells and lead to DNA damage, Burbidge said. And this damage can lead to mutations - such as the BRAF V600E mutation - which can accumulate over time and can lead to the development of cancer.
Indoor tanning at younger ages, and for longer or more frequent sessions, can increase the amount of DNA damage.
UV damage to skin cells is seen visually as a sunburn or a suntan.
Overall, 105 melanomas in the study, or 36 per cent were BRAF-mutant, researchers report in the Journal of the National Cancer Institute. Most cases were BRAF V600E mutations.
Mutations were more frequent with indoor tanning group for all areas of the body exposed to the sun, although in some parts of the body the difference was too small to rule out the possibility that it was due to chance.
Beyond its small size, another limitation of the study is that it was done at a single center in Canada, where the effects of sun exposure may not be as pronounced as they are elsewhere in the world.
Because of the distance from the equator and longer winters in Calgary, the study results may underestimate the impact of indoor tanning on melanoma risk, said Dr David Leffell, chief of dermatologic surgery at Yale School of Medicine in New Haven, Connecticut.
UV radiation from the sun is well known to mutate genes that can lead to melanoma and other types of skin cancer, Leffell, who wasn't involved in the study, said by email.
"The same effect occurs with the artificial UV that people are exposed to in UV beds or otherwise artificial UV for the purposes of indoor tanning," Leffell said. "The earlier you get exposed to UV, the bigger the burden of mutations that accumulate over time and can cause cancer."
In addition to avoiding any form of indoor tanning, people also need to take precautions outdoors, said Dr Elizabeth Martin, president of Pure Dermatology & Aesthetics in Hoover, Alabama. This includes staying in the shade in the middle of the day, wearing long sleeves and pants, and donning wide-brimmed hats and sunglasses.
"And, apply a broad-spectrum, water-resistant sunscreen with an SPF of 30 or higher to all sun-exposed skin prior to going in the sun, and reapply every two hours or immediately after swimming or sweating," Martin, who wasn't involved in the study, said by email.