Melanoma, the deadliest form of skin cancer, has increased rapidly in the United States in recent years, a new study reveals. Some experts have argued that the rising rates are merely a result of expanded screening, which catches small tumors that otherwise might go undetected. But the study by the Northern California Cancer Center in Fremont, Calif., casts doubt on this viewpoint.
It found a 3.1 percent annual rise in malignant melanoma rates among white men and women from 1992 to 2004. White people account for more than 90 percent of such cases nationwide.
The study did not draw conclusions about the reasons for the increase, but some experts believe leisure activities in the sun play a role.
"This is not explained away by screening," said research scientist Tina Clarke. "Rates of melanoma are increasing, and it's real."
The study, which included researchers from Stanford University and elsewhere, appeared in the Jan. 8 edition of the Journal of Investigative Dermatology.
The fastest increases are occurring among white men over the age of 65. Such men were diagnosed with malignant melanoma at the rate of 126 cases per 100,000 people in 2004. That rate is rising by 5 percent per year, which would result in a doubling over a 20-year period, the study noted.
White women over 65 had a smaller, but also significant, increase in rates.
These numbers were not surprising to Dr. Adil Daud, director of melanoma clinical research at University of California-San Francisco. "In that population, I do think that there's been an increased number of people who are either moving to the southern part of the United States where there's more sun and also playing more golf and out sailing more and hanging out by the beach more," said Daud, who was not involved in the study. "I do think that it's a genuine increase because of our lifestyle."
Melanoma can appear on the skin suddenly without warning, but it also can develop on an existing mole. It involves the uncontrolled growth of pigment-producing cells.
About 65 to 90 percent of melanomas are caused by exposure to ultraviolet light or sunlight, according to the national Centers for Disease Control and Prevention.
For that reason, experts advise people to limit their sun exposure, use sun screen with a sun protection factor of at least 15 that guards against both UVA and UVB rays, and to take extra precautions near water, snow and sand because these elements can reflect the damaging rays of the sun and increase the chance of sunburn.
Genetics also play a role in making some people more susceptible to melanoma, Daud said.
People at highest risk include those with light skin color, a family history of skin cancer, skin that easily burns or freckles, a history of sunburns early in life, and those with blue or green eyes, blond or red hair, and a large number of moles.
To help determine whether better screening is the cause of the increase, researchers decided to focus on thick tumors. Screening may pick up more thin tumors, they reasoned, but people who have thicker growths would have had the problem longer and as a result, may not have had access to screening.
The study found that even the thickest tumors increased at a rate of 3.86 percent per year.
Researchers also decided to look at different socioeconomic groups. They assumed that people in low-income neighborhoods are less likely to be screened.
"In the poor neighborhoods where you would think that they might not have great access to screening, the very thick kind of tumors were going up. Everything was going up," Clarke said. "So that really does point to it being a true increase."
Experts advise people to do regular self-examinations, including looking for atypical moles that are larger than normal, vary in color or have irregular borders.
Regular screening by a dermatologist also is recommended for those who are at high risk.
If melanoma is caught early enough, the survival rate is very high, said Dr. William Crain, an Oakland, Calif., dermatologist who volunteers at free screenings.
"We're particularly hoping to serve people who don't have a private physician," he said.
Crain speculates that increasing affluence played a role in the rising melanoma rates. Before the current financial downspin, many people had the time and financial wherewithal to vacation in sun-drenched places like Palm Springs, Calif., or Hawaii. People would spend hours outdoors, sometimes getting severe sunburns.
Despite the dramatic rise in melanoma, the study found that death rates have remained relatively stable in recent years. The expanded screening and detection of tumors, which can be removed, before they have spread may explain this trend.
The American Academy of Dermatology estimates that the 2008 death toll from melanoma in the United States was 5,400 men and 3,020 women.
The five-year survival rate for people whose melanoma is detected and treated before it spreads to the lymph nodes is 99 percent, the group says.
Clarke stressed the need to act quickly if people see something that looks suspicious.
"The problem with melanoma, unlike a lot of other cancers, is that it is very quick to metastasize (or spread) relative to other types of tumors," she said. "So the difference between catching a melonoma early and not having a real problem after that, or catching it late and having it kill you, could be like six months. So you really have to get in there and get it checked out as soon as you see it."
Studies in Australia have shown an increase in melanoma rates in the northern section of the country, which is more tropical. That also suggests that the increase is real and is sun-related, Daud said.
Like Clarke, Daud urges people to act quickly if they believe they may have a problem.
"Melanoma is highly curable early," he said, "and it's highly incurable late."
In addition to screening by a dermatologist, experts advise people to perform regular self-exams, including:
• Examine your body front and back in the mirror, then right and left sides with arms raised.
• Bend elbows and look carefully at forearms, upper underarms and palms.
• Look at the backs of your legs and feet, the spaces between your toes and on the sole.
• Examine the back of your neck and scalp with a hand mirror. Part hair for a closer look.
_Check your back and buttocks with a hand mirror.
Source: American Academy of Dermatology
(c) 2009, Contra Costa Times (Walnut Creek, Calif.).
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