Sunlight may help cancer victims survive

[Guest guest]

Health - AP

 

By RANDOLPH E. SCHMID, Associated Press Writer

 

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. As for what people should do to gain

sunlight's benefits without its downsides, an editorial accompanying

the studies said more research is needed.

 

" 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, being published this week in the Journal of the

National Cancer Institute (news - web sites), 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 in developed

countries with Caucasian populations, and studies have consistently

found exposure to the sun a major risk factor.

 

However, a new look at 528 melanoma victims over five years also

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 totally counterintuitive, and we're trying to investigate it, "

said Berwick, noting that she is now doing a similar study of 3,700

melanoma patients worldwide.

 

" 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 in a

telephone interview.

 

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.

 

Another possibility is solar elastosis, a response to sunlight that

breaks down collagen in the skin — the same process that causes sun-

related wrinkling.

 

" It may be something in solar elastosis itself ... it may be that

some physical barrier created by this breakdown of collagen keeps the

melanoma from getting into the blood and lymph system, " Berwick said.

 

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.

 

Vanderbilt's Egan, who was not involved in either research team, said

it's unlikely to be sunlight itself that is an explanation of these

findings.

 

The scientific community is converging on the idea that Vitamin D is

likely to be a protective agent in cancer, she said in a telephone

interview.

 

" 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.

 

In an accompanying commentary in the journal, Egan and co-researchers

at Vanderbilt say the two findings are of particular interest because

non-Hodgkin's lymphoma is suspected of being caused in a way similar

to skin cancer.

 

More than a million cases of skin cancer are attributed to sun

exposure annually in the United States, with about 54,000 cases of

melanoma diagnosed each year, noted the Vanderbilt researchers, which

also included Jeffrey A. Sosman and William J. Blot.

 

Berwick's research was supported by the U.S. National Cancer

Institute while Smedby's was funded by the U.S. National Institutes

of Health (news - web sites), the Swedish Cancer Society, Plan

Denmark and the Danish National Research Foundation.

 

On the Net:

 

Journal of the National Cancer Institute:

http://jncicancerspectrum.oupjournals.org