Do tanning beds cause cancer? Does their risk outweigh the risks of vitamin D deficiency in northern countries?

Question

For a long time I've heard that tanning beds cause cancer. Here a quote from an article on MSNBC in 2009:

International cancer experts have moved tanning beds and other sources of ultraviolet radiation into the top cancer risk category, deeming them as deadly as arsenic and mustard gas.

For years, scientists have described tanning beds and ultraviolet radiation as "probable carcinogens."

A new analysis of about 20 studies concludes the risk of skin cancer jumps by 75 percent when people start using tanning beds before age 30. Experts also found that all types of ultraviolet radiation caused worrying mutations in mice, proof the radiation is carcinogenic. Previously, only one type of ultraviolet radiation was thought to be lethal.

I've had a couple physicians tell me that in Canada and other northern countries there's a greater risk of harm from vitamin D deficiency. This would suggest that even though tanning beds are harmful, the risks of tanning beds may be weighted against their health benefits.

Here's a quote from an article on CBC in 2007:

A tanning bed with medium-pressure lamps that generate UVB rays is one way to help the body make vitamin D during months when the sunshine is weak

The article also notes that rates of cancer increase significantly when one is deficient in vitamin D.

Do tanning beds cause cancer? This has long been touted and is widely cited in the media, so I expect there's scientific evidence to back it up.

More difficult to answer is whether the risk of cancer arising from the use of tanning beds is greater than the risk of vitamin D deficiency. Is there scientific evidence illuminating this theory?

Answer 1

First of all, using tanning beds to fight against vitamin D deficiency is in my opinion ridiculous as supplement pills are cheap and to my knowledge have no cancer risk associated to them. At least a couple of researchers agree with me on this (Woo & Eide, 2010):

Tanning bed proponents cite the health benefits of vitamin D to support indoor tanning, including concerns that reduced vitamin D levels or certain vitamin D receptor polymorphisms may be associated with increased incidence of various cancers, including cutaneous melanoma. However, most tanning devices primarily emit ultraviolet A, which is relatively ineffective in stimulating vitamin D synthesis. Health benefits can be fully dissociated from the ultraviolet exposure risks with vitamin D supplementation, although optimal levels remain to be established. Indoor tanning represents an avoidable risk factor for skin cancer, and education of the general public as well as the enactment and stricter enforcement of indoor tanning legislation are a public health imperative.

Riker et al. (2010) gathered the results of several papers on the skin cancer risk :

The increase in indoor tanning is alarming when viewed relative to strong evidence that links indoor UV radiation exposure via tanning bed usage to skin cancer. A recent study analyzing patients diagnosed with basal cell carcinoma, squamous cell carcinoma, and 540 controls showed that those who have used a tanning device previously were at a 50% higher risk for developing basal cell carcinoma (odds ratio [OR] 1.5; 95% confidence interval [CI]: 1.1-2.1) and more than double the risk for squamous cell carcinoma (OR, 2.5; 95% CI: 1.7-3.8).53 Ting et al40 found that use of a tanning bed by 1,518 dermatologic patients showed a 64% increase in the risk of developing melanoma (OR, 1.64; 95% CI: 1.01-2.67), with a stronger risk in women <39 years old (OR, 3.22; 95% CI: 1.01-11.46).

A 2007 study by the IARC revealed that the first exposure to indoor tanning prior to the age of 35 was associated with a 75% increased risk of developing melanoma (RR, 1.75; 95% CI: 1.35-2.26).54 A Swedish study showed that people who regularly use tanning beds have a relative risk for developing melanoma of 1.8, with a much higher risk for those <36 years old of 8.1, adjusting for hair color, raised nevi, skin type, and number of sunburns.55 A Norwegian and Swedish study of 106,379 women demonstrated that regular (at least once per month) solarium use at any age had a 55% increased risk of developing melanoma, with the greatest association in the 20- to 29-year-old age group.56

In essence indoor tanning is quite likely a risk factor for skin cancer. Basically it boils down to whether getting a tan is worth the cancer risk increase. Vitamin D is easier and cheaper to get in pill form.