Sun Struck: Data suggest skin cancer epidemic looms

Janet Raloff

Young adults are experiencing a sharp increase in the incidence of non-melanoma skin cancers, a new study finds. These readily treatable tumors had been considered mainly a problem for people over age 60.

The youthful trend "is more than surprising. It's alarming," says study leader Leslie J. Christenson, a dermatologic surgeon at the Mayo Clinic in Rochester, Minn. Her study focused on basal cell and squamous cell carcinomas, which are less dangerous than melanoma but, if untreated, can be disfiguring or even lethal.

Once someone develops a non-melanoma skin tumor, says Christenson, there's a 50 percent chance that another tumor will show up within 2 to 3 years. "Among people who get a second, 75 percent will go on to get a third," she adds. The study's finding of a surge in basal cell and squamous cell cancers among people in their 20s and 30s could herald "a potentially exponential increase in the cancers' incidence over time, as these people age," Christenson told Science News.

Her team analyzed data collected as part of a local health study. These data included medical information on more than 99 percent of the population in the Minnesota county where the clinic is located.

Christenson's team tallied reports of non-melanoma skin cancers in people under 40 between 1976 and 2003. In the Aug. 10 Journal of the American Medical Association, the researchers report that the incidence of basal cell skin cancers roughly tripled during that period among adult women, to more than 30 cases per 100,000 individuals. Men experienced only a slight increase, to 27 cases per 100,000.

The incidence of squamous cell carcinoma was consistently lower than that but has quadrupled since the mid-1970s—to 4 cases per 100,000 people.

According to the Schaumburg, Ill.–based American Academy of Dermatology, non-melanoma skin cancers will claim the lives of some 2,800 people in the United States this year.

Over time, improvements in screening can increase the number of cancers identified, but that effect doesn't appear to explain the new data, Christenson's team says. Better screening tends to turn up cancer in an earlier stage, but no such shift to earlier skin cancers emerged in the Minnesota data.

In contrast, a separate team has reported that a sharp rise in melanoma cases among Medicare beneficiaries between 1986 and 2001 was "confined to early stage cancer." Researchers at Dartmouth Medical School in White River Junction, Vt., correlated a more than doubling in melanoma cases to an identical rise in screening for the disease and so argue against any rise in melanoma incidence. Their report appears in the Sept. 3 British Medical Journal.

Overexposure to ultraviolet light is the leading risk factor for skin cancers, and 80 to 90 percent of non-melanoma skin cancers occur on typically sun-exposed sites, such as the head or neck. In the new study by Christenson's team, only 60 percent of non-melanoma skin cancers occurred there, with most of the others showing up on the torso. This suggests full-body tanning as the source, Christensen says.

"I'm glad somebody documented this," says John A. Carucci, head of dermatologic surgery at Cornell University's Weill Medical College in New York City. He has noticed an increase in non-melanoma skin cancer in young adults and on the torso in his own practice. He concludes, "People are tanning more, and this [skin cancer], unfortunately, is the price people are paying."

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Letters:

This article gives the impression that the increase in skin cancer among young people is caused by tanning in the sun. Environmental factors such as ozone depletion should have at least been referenced in the article.

Cathy Hodge McCoid
Sacramento, CA

In your article, the conclusion that young people are getting more skin cancers because "people are tanning more" does not seem to be supported by the research as reported. The research seemed to be based on the number of cancers, not the amount of tanning. Growing up in the 1940s and 1950s, my friends and I spent all day everyday in the California sun without benefit of sunscreen. I question the effects of the chemicals in the suntan lotions slathered on kids today every time they go outside (which, with the advent of television and computer games, is much less frequently).

Amy Emerson
Elko, NV

References:

Christenson, L.J., et al. 2005. Incidence of basal cell and squamous cell carcinomas in a population younger than 40 years. Journal of the American Medical Association 294(Aug. 10):681–690. Abstract available at http://dx.doi.org/10.1001/jama.294.6.681.

Welch, H.G., S. Woloshin, and L.M. Schwartz. 2005. Skin biopsy rates and incidence of melanoma: Population based ecological study. British Medical Journal 331(Sept. 3):481. Available at http://dx.doi.org/10.1136/bmj.38516.649537.E0.

The U.S. Environmental Protection Agency's "EnviroFlash: UV Index Forecast and Alert Notification" e-mail service is available at https://enviroflash.epa.gov/uv/

Further Readings:

2005. American Academy of Dermatology issues statement urging the public to be smart in the sun. American Academy of Dermatology press release. May 25. Available at http://www.aad.org/aad/Newsroom/Vitamin+D.htm.

2003. The truth about sunscreens. American Academy of Dermatology press release. Oct. 22. Available at http://www.aad.org/public/News/NewsReleases/Press+Release+Archives/Skin+Cancer+and+Sun+Safety/PhotoProtectionRigel.htm.

1996. Here comes the sun … and wrinkles. Science News 149(Feb. 10):93.

1994. Estimating UV's human cancer risk. Science News 146(Oct. 15):255.

Pennisi, E. 1993. Visible, UV-A light tied to skin cancer. Science News 144(July 24):53.

A skin cancer fact sheet from the American Academy of Dermatology is available at http://www.aad.org/NR/exeres/A388571A-284F-490B-BA4F-BE5B417DD7D7.htm.

The National Weather Service Climate Prediction Center's stratosphere UV index is available at http://www.cpc.ncep.noaa.gov/products/stratosphere/uv_index/.

Sources:

American Academy of Dermatology
P.O. Box 4014
Schaumburg, IL 60168-4014
Web site: http://www.aad.org/

John A. Carucci
Weill Medical College
Cornell University
New York Presbyterian Hospital
525 E. 68th Street
Star 326
New York City, NY 10021

Leslie J. Christenson
Department of Dermatology
Mayo Clinic
200 First Street, SW
Rochester, MN 55905

NOAA/National Weather Service
National Centers for Environmental Prediction
Climate Prediction Center
5200 Auth Road
Camp Springs, MD 20746

SunWise Program
U.S. Environmental Protection Agency
1200 Pennsylvania Avenue, N.W.
Washington, DC 20460

From Science News, Volume 168, No. 7, August 13, 2005, p. 99.