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Sunlight may help victims survive some cancers

WASHINGTON - Sunlight exposure, a major risk factor for the potentially deadly skin cancer melanoma, may also help victims survive that disease, new research indicates.

And a second study indicates that exposure to sunlight may reduce the risk of getting cancer of the lymph glands.

Researchers stress that their findings do not mean people should rush out and start baking in the sun.

"Sunlight, particularly ultraviolet radiation, is a very well-established human carcinogen. Nothing in these papers should in any way detract from this message," said Kathleen M. Egan of Vanderbilt University Medical Center.

But the new reports, published in the Journal of the National Cancer Institute, do provide important clues to the development of these cancers and some factors that may slow or stop them.

Melanoma has been increasing over the past half-century, and studies have consistently found exposure to the sun a major risk factor.

A look at 528 melanoma victims over five years found that increased sun exposure led to increased survivability, according to the study led by Marianne Berwick of the department of internal medicine at the University of New Mexico.

"It's really strange, because sunburn seems to be one of the factors associated with improved survival, and that doesn't make much sense, so we think sunburn's a proxy for the kind of sun exposure that leads to melanoma. But there's so much we need to know," Berwick said.

She said Vitamin D, which the skin makes in response to sunlight, may be a factor. Vitamin D can help regulate cell growth and help cells stop unneeded growth through a process called apoptosis.

In the second study, a research team led by Karin Ekstrom Smedby of the Karolinska Institute in Stockholm, Sweden, studied 3,000 lymph cancer patients and a similar number of people without lymph cancer in Denmark and Sweden.

They found that increased exposure to ultraviolet radiation through sunbathing and sunburns resulted in a reduced incidence of non-Hodgkin's lymphoma.

The scientific community is converging on the idea that Vitamin D is likely to be a protective agent in cancer, she said.

"It's long been known that Vitamin D is a critically important agent in bone health," she noted. "More recently it has become increasingly obvious that Vitamin D has important regulatory functions in the cell, in terms of cell division," she said.

The two findings are of particular interest because non-Hodgkin's lymphoma is suspected of being caused in a way similar to skin cancer.

[Last modified February 28, 2005, 16:11:03]