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Women who use indoor rays to keep up a tan have a somewhat increased risk of skin cancer, a new study finds – adding to evidence that baking in a tanning bed can be as bad as baking under the sun.
Many studies have linked tanning beds to skin cancer risk, and the International Agency for Research on Cancer considers artificial UV radiation a human carcinogen.
But not all studies have found tanning beds to be a risk. And the link to basal cell carcinoma – by far the most common form of skin cancer – has been inconsistent.
It's thought that about one in five Americans will develop skin cancer at some point in their lives. And basal cell carcinoma – a highly curable cancer – accounts for most of those cases.
Few women develop melanoma
For the new study, Jiali Han and colleagues at Harvard Medical School looked at data from nearly 730,000 US nurses followed for 20 years.
They write in the Journal of Clinical Oncology that women who used tanning beds in their younger days were more likely than others to develop skin cancer – basal cell carcinoma, in particular.
Women who'd used tanning beds at least four times per year between high school and age 35 were 15% more likely to develop basal cell carcinoma than non-users were.
There were similar risks tied to melanoma and squamous cell carcinoma – a skin cancer that, like basal cell, has a high cure rate. But in the case of melanoma the finding was not statistically significant – which means it could be due to chance.
Part of that could be due to the small number of women who developed melanoma, according to Han's team.
Melanoma a deadliest form of skin cancer
Of the 730,000 women, just 349 were diagnosed with melanoma during the study. That compared with 5,500 women diagnosed with basal cell carcinoma.
Melanoma is fairly rare – white people have about a 2% chance of developing it, and the risk is much smaller in darker-skinned people. But it is the deadliest form of skin cancer.
Other studies have also tied indoor tanning to melanoma, noted Dr June K. Robinson, a research professor of dermatology at Northwestern University in Chicago who was not involved in the study.
"This is a very large, well-done study that supports prior findings that indoor tanning is associated with developing melanoma and squamous cell carcinoma," Robinson told Reuters Health in an email.
It also adds evidence that indoor rays contribute to basal cell carcinoma as well, she said.
Minors banned from using tanning beds
An important finding, according to Robinson, was that the risk seemed to climb with just a few trips to the tanning salon each year. "Many people tan 20 or more times per year," she noted.
And the findings hint that there may be a greater risk the earlier a person starts tanning.
Women who'd used tanning beds at least seven times a year during high school and college were 73% more likely than non-users to eventually be diagnosed with basal cell carcinoma.
The findings, Han's team writes, "support warning the public against future use of tanning beds" – and boost the argument for restrictions on salons.
A number of countries have banned minors from using tanning beds, the researchers note. And last year, California became the first US state to bar anyone under age 18 from using indoor tanning devices – though other states also have certain restrictions on minors.
(Amy Norton, Reuters Health, March 2012)
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