The good sun? Posted Friday, September 2, 2005 by arjuna
http://www.boston.com/news/globe/health_science/articles/2005/08/29/the_good_sun?mode=PF

Skin cancer is as deadly as ever, but now some doctors wonder if avoiding all rays is the answer

By Brian Kladko, Globe Correspondent | August 29, 2005

All it takes is a trip to the South Boston waterfront to see that dermatologists have a long way to go in their campaign against melanoma, the deadliest form of skin cancer.

Among those recently basking in the hazy sunshine at Carson Beach were Karen and Ed Crowley, both 46, of Dorchester. They had been lying out for more than two hours without sunscreen because they forgot to pack it.

''What are you going to do?" said a bare-chested Ed, a construction worker who said he also takes his shirt off at job sites, as long as temperatures allow for it. ''You want to walk through life afraid of everything?"

A few feet away, Lynn Krause was working on her tan, too. She deliberately shunned the sunscreen.

''If you're out to get a tan, then there's no point in using it," said the 34-year-old South End resident. As for skin cancer, she said, ''Whatever happens, happens."

Whether they're lying on Carson Beach, fishing in Boston Harbor, or skiing on Mount Snow, Americans still blithely defy dermatologists' warnings that melanoma is a growing menace, caused mostly by people's bad habits.

Named for the pigment-producing skin cells, called melanocytes, where the disease takes root, melanoma will afflict another 60,000 Americans this year and kill about 8,000. Unlike the two most common forms of skin cancer, melanoma can spread to other parts of the body, making it far more lethal.

But some skeptics question the very notion that melanoma is on the rise. And there's a growing disagreement about the dangers of moderate sun exposure. Some doctors argue that 10 to 15 minutes per day of sunshine, without sunscreen, will prevent far more cancers than it will cause. Others suggest getting enough rays to turn the skin pink a few times a week.

''We just need to be sensible about it," said Kathleen Egan, an epidemiologist at Vanderbilt University School of Medicine. ''Common sense says that you don't want to overdo it in the sun, and that you should let your own susceptibility to the sun be the arbiter."

The claim that some sun could help the body ward off cancer, or better cope with it, isn't so new -- 25 years ago, researchers noted that cancer rates were higher in northern parts of the United States, where people get less sun exposure. (That's not true for melanoma -- it's more prevalent in Texas than Minnesota.) But the notion of healthy sunshine seems to be gaining momentum.

One study of 900 men in California found that men with darker tans had half the risk of advanced prostate cancer. Another study, looking at 6,000 people in Denmark and Sweden, found that people with a reported history of sunburns and sunbathing were less likely to get the disease.

Perhaps the most provocative finding came from Marianne Berwick, an epidemiologist at the University of New Mexico. In a study of 650 melanoma patients in Connecticut, she found that people who reported more sun exposure over their lifetimes had a better chance of surviving the disease. In other words, the same sunlight that could be a risk factor for melanoma could also increase the chances of beating it.

The most popular explanation for these findings is Vitamin D, which is manufactured by the skin when exposed to sunlight, assuming there's no sunscreen on it. People living in most of the United States -- including New England -- have a hard time making any Vitamin D during winter months and tend not to get the federal government's recommended daily intake from their diets, said Egan, who wrote an editorial accompanying Berwick's article. She also believes, like many other scientists, that the government's recommendations are too low.

But dermatologists maintain that sun, particularly intense sun, ''is the most avoidable risk factor that we know about," said Martin A. Weinstock, a Brown University dermatology professor and chairman of the American Cancer Society's skin cancer advisory group.

Weinstock said most of the Vitamin D-cancer research ''has been rather weak." Even if it proves true, he said, a concerned person would do better to get the nutrient by taking a pill or changing their diet (milk is fortified with it).

As the risks and benefits of sunshine become hopelessly muddled, a seemingly basic issue -- whether melanoma is on the rise -- has become just as cloudy.

Federal statistics show that US cases of the disease grew 2.4 percent a year between 1992 and 2002, making it the third-fastest growing cancer in the country.

But Dr. H. Gilbert Welch, a professor of medicine at Dartmouth Medical School, says most of that increase may be an illusion -- the result of more people being screened through programs like ''Melanoma Mondays," in which dermatologists offer free, on-site exams.

Welch, author of last year's ''Should I Be Tested for Cancer? Maybe Not and Here's Why," reported this month in the British Medical Journal that the average biopsy rate and diagnosis rate increased about 2.5 times between 1986 and 2001 for people 65 and older. But almost all that increase involved early-stage melanomas; the proportion of late-stage melanomas and the death rate stayed about the same. If the disease were truly on the rise, he said, the number of late stage cases and deaths should have risen, too.

''We're finding cases that we simply didn't find before," he said. ''But these aren't cases that are going to kill people."

Welch notes that many lesions diagnosed as melanoma won't become invasive. Also, doctors often disagree on which lesions are melanoma and which aren't, and in the face of that ambiguity, they err on the side of caution.

But just days before Welch's article appeared, the Journal of Clinical Oncology published an article saying childhood melanoma increased about 3 percent between 1973 and 2001. One of its authors, Dr. John Strouse, a pediatric oncologist at the Johns Hopkins University School of Medicine, believes at least some of that increase is real -- not just the result of more examinations.

Strouse suspects it's no coincidence 15- to 19-year-olds account for most of the increase, as it's those years when a nice tan takes on more importance. He also believes the increase in travel to sunny climes and the profusion of tanning salons has fueled the trend.

''I was down in Memphis for a meeting, and we were at a hotel there, and there was some high school dance at this hotel," he said. ''And all the girls were tan -- in February. And Memphis isn't that sunny. If you're tan in February, you're tanning indoors or you just went on vacation someplace."

Anecdotes like that make dermatologists wary of any research that muddles their message. In a country not known for moderation, they fear that people will disregard their warnings and, like the people on Carson Beach, soak up too much sun.

''Certainly the dermatology community has had this boring, 'no fun' story about staying out of the sun that's been going on really for 40 years or 50 years," said Dr. Barbara Gilchrest, chairwoman of the dermatology department at Boston University School of Medicine. But publicity about the recent findings of sun exposure's possible benefits, she said, ''was not a helpful public health message."

Signs of possible melanoma
# A mole that changes in size, shape, or color; has irregular edges or borders; is more than one color; is asymmetrical; oozes, bleeds, or is ulcerated so the underlying tissue shows through.
# A change in colored skin.
# Satellite, or new moles that grow near an existing one.

SOURCE: National Cancer Institute