The International Agency for Research on Cancer (IARC) is a section of the
World Health Organization whose mission is to develop strategies for cancer
prevention and control. In June 2009, the agency convened a working group
of 20 scientists to reassess the carcinogenicity of various sources of
radiation. In the past, the IARC has found sufficient proof that solar
radiation is a human carcinogen involved in the development of basal cell
carcinomas, squamous cell carcinomas, and melanoma. The current working
group now finds unquestionable evidence that UV-emitting tanning devices
cause melanoma of the skin and of the choroid and ciliary body of the eye.
This determination is based on a comprehensive meta-analysis finding that
risk for cutaneous melanoma increases by 75% when tanning device use begins
before age 30, compared with nonuse (Int J Cancer 2006; 120:1116). The
group also cites case-control studies showing increased incidence of ocular
melanoma among users of UV-emitting tanning devices (Int J Cancer 2004;
112:896). Their conclusions are supported by mechanistic studies in animal
models that show a cytidine-to-thymidine transition in DNA caused by UVA
radiation. In humans, this mutation is found in TP53 in premalignant solar
keratosis and in malignant skin tumors.
Comment: This report, by a highly respected independent group, validates
what dermatologists have known for a long time -- that tanning beds cause
melanoma. Tanning beds now justly take their place along with x-rays and
gamma rays at the forefront of radiation carcinogens. Physicians can cite
the IARC conclusions when counseling patients, especially younger
individuals, about the hazards of tanning bed use.
-- Craig A. Elmets, MD
Published in Journal Watch Dermatology July 30, 2009 Citation(s):
El Ghissassi F et al. A review of human carcinogens -- Part D: Radiation.
Lancet Oncol 2009 Aug; 10:751.