Researchers in the US found that not only does indoor
tanning increase melanoma risk, but that the risk rises with how often a person tans, regardless of their age, gender, or the type of
indoor tanning device they use. They established this via a case-controlled study that overcame many of the limitations of previous investigations that had only found a weak link between indoor tanning and increased risk of melanoma.
You can read about the study in the Published Online First 26th May issue of Cancer Epidemiology, Biomarkers and Prevention, a journal of the American Association for Cancer Research.
Principal investigator Dr DeAnn Lazovich, associate professor of epidemiology at the University of Minnesota's School of Public Health and co-leader of the Prevention and Etiology Research Program at the University's Masonic Cancer Center, said in a statement that they found it didn't matter what type of tanning device people used, "there was no safe tanning device".
She said they also found, and this has not been found before, that the risk of getting melanoma was more strongly linked with how much time a person spent getting a tan than it was to the age at which they started doing it.
"Risk rises with frequency of use, regardless of age, gender, or device," said Lazovich. She also commented that before this study, indoor tanning had been only weakly linked with melanoma risk.
"Most reports were not able to adjust for sun exposure, confirm a dose-response, or examine specific tanning devices," said Lazovich.
"Our population-based, case-control study was conducted to address these limitations," she added.
Melanoma is the most serious form of skin cancer: it accounts for only 4 per cent of skin cancer cases but it causes 79 per cent of deaths, partly because it is difficult to treat, particularly when it is advanced.
Melanoma is one of fastest increasing cancers in the US, and also in Minnesota, where there is a high prevalence of indoor tanning. It is expected that this year about 69,000 Americans will be diagnosed with it, including some 1,000 Minnesotans, said the researchers.
For the study, Lazovich and colleagues searched a statewide cancer registry for cases of invasive cutaneous melanoma in patients aged from 25 to 59 diagnosed in Minnesota between 2004 and 2007.
They matched the cancer cases by age and gender to a control group randomly selected from state driver's license lists.
To get data on indoor tanning exposure, such as if ever used, types of device, age when first used, dose, period of use, how long for, frequency, and incidence of indoor tanning related burns, the researchers invited the cancer patients and the controls to complete a paper questionnaire and take part in a comprehensive telephone interview that lasted about an hour.
By these means they got enough data for analysis from 1,167 cases of melanoma and 1,101 matched controls.
They found that:
- 62.9 per cent of the melanoma patients and 51.1 per cent of the controls had tanned indoors.
- Among these, ie participants who had used any type of indoor tanning device at least once, the risk of getting melanoma was 74 per cent higher than people who had never used an indoor tanning device.
- Frequent users of indoor tanning beds (ie who had been indoor tanning for 10 or more years, or who totalled 50 or more hours or more than 100 or more sessions) were 2.5 to 3 times more likely to develop melanoma than those who had never used one.
- The risk of developing melanoma was approximately 3 times higher among users of UVB-enhanced devices and 4.4 times higher among those who used primarily UVA-emitting devices.
- The increased risk of developing melanoma was mostly independent of age and gender.
"In a highly exposed population, frequent indoor tanning increased melanoma risk, regardless of age when indoor tanning began. Elevated risks were observed across devices."
They cautioned that this study was not able to determine if it was mostly UVA or UVB that was responsible for the elevated risks.
The researchers proposed that the study overcame some of the limitations of earlier studies and reinforced the recent statement by the World Health Organization's International Agency for Research on Cancer (IARC) that tanning devices are carcinogenic in humans.
"Indoor Tanning and Risk of Melanoma: A Case-Control Study in a Highly Exposed Population."
DeAnn Lazovich, Rachel Isaksson Vogel, Marianne Berwick, Martin A. Weinstock, Kristin E. Anderson and Erin M. Warshaw.
Cancer Epidemiol Biomarkers Prev, 1055-9965.EPI-09-1249; Published Online First May 26, 2010.
Source: University of Minnesota.
Written by: Catharine Paddock, PhD