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ST. PAUL, Minn. - Skin cancer victims younger than 40 are almost twice as common today as they were 30 years ago, according to a Mayo Clinic study.
The finding puts scientific fact behind a long-held belief that skin cancer is growing in the United States.
The study also offers some evidence that skin cancer actually is more common today and not just the result of increased screening or of people increasing their odds of skin cancer simply by living longer.
"We're seeing it in younger and younger people," said Dr. Leslie Christenson, the lead author of the study, which was published in this week's Journal of the American Medical Association.
Skin cancer experts at Mayo Clinic in Rochester, Minn., became interested when they noticed high numbers of young patients seeking treatment for nonmelanoma skin cancer, which is the most common and most treatable form of skin cancer. About 1 million new cases are diagnosed each year.
The researchers turned for answers to the Rochester Epidemiology Project, which is a comprehensive collection of medical records of residents of Olmsted County, Minn. Reviewing records between 1976 and 2003, the researchers saw a particularly substantial increase in nonmelanoma among women younger than 40.
Christenson said the location of the cancer tumors was telling. Usually, 80 percent to 90 percent of skin cancer tumors are found above the neck. Among women with nonmelanoma, only half had such tumors. The rest had tumors on their torso or arms or legs - suggesting sun exposure due to excessive outdoor tanning or the use of tanning beds.
Nonmelanoma accounts for 97 percent of skin cancers and can usually be treated by surgical removal of the cancerous tumors. Melanoma accounts for the rest and is a more severe form of cancer.
An analysis released this week of federal Medicare spending suggested that melanoma is being diagnosed at twice the rate among senior citizens than it was a decade ago. But the study questioned whether the increased diagnosis was worth the financial cost, because the nation's melanoma-related death rate hadn't dropped in that time period.
Christenson said the same could be true with her team's discovery regarding nonmelanoma. It is possible that increased awareness and screening resulted in more detection of existing tumors.
Her study wasn't designed to determine why there was an increase, just to prove that there was an increase. However, she did find some evidence that suggests this is more than just additional screening.
The tumors found in patients today were, on average, the same size as the tumors found in patients 30 years ago. If early screening were the cause of more nonmelanoma cases today, Christenson said, then it would be logical that the tumors would be found earlier and would be substantially smaller.
Screening may not be affecting the death rate, but early detection of skin cancer certainly can make surgical removal of a tumor less invasive, said Dr. Ted Buselmeier, a skin cancer specialist based in Coon Rapids, Minn.
"Previously, these things got out of hand and people lost a nose or lost an ear or lost an eye. That doesn't happen so much anymore," Buselmeier said.
The Mayo study listed ozone depletion, increased screening of skin cancer and increased exposure to UV light as the most likely causes for the increase in cases among people younger than 40.
Because the demographics of the Olmsted area are largely white, the conclusions of the study only show a definitive increase in nonmelanoma among that racial group. People with darker skins have lower risks, she said, but they still have substantial risks.
Prevention includes limiting exposure to the midday sun and using sunscreen appropriately. Early thinking about skin cancer is that it was a chronic disease developed over decades of exposure to ultraviolet rays of the sun. The increase in young cases suggests individual episodes of unprotected exposure also are damaging, she said.
"What we're seeing," she said, "is probably some episodes of intense exposure are stimulating this."
(c) 2005, St. Paul Pioneer Press (St. Paul, Minn.). Distributed by Knight Ridder/Tribune News Service.