Sunlight may have unexpected anti-cancer effects

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Sunlight may have unexpected anti-cancer effects

2005-02-07

 

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Two new studies suggest that exposure to sunlight might not be as

risky for cancer as is generally believed.

 

Scandinavian researchers show that high UV radiation exposure is

associated with a reduced risk of lymphoma, while another team

reports that sunlight-related melanoma skin cancers appear to be

inherently less aggressive than those that arise in non-exposed

areas.

 

Dr. Karin Elkstrom Smedby, from the Karolinska Institute in

Stockholm, and colleagues investigated ultraviolet radiation

exposure as a possible cause for the increasing rates of malignant

lymphoma seen in recent decades.

 

Instead, the researchers found that high UV radiation exposure, as

measured by frequent sunbathing and sunburns, cut the risk of the

non-Hogkins type of lymphoma by up to 40 percent depending on the

level of exposure.

 

The study involved 3740 patients with malignant lymphomas who were

compared with 3187 matched " controls " from the general population.

High UV radiation exposure also seemed to protect again the

Hodgkin's type of lymphoma, but the association was weaker than with

non-Hodgkin's disease.

 

In another study, also reported in the Journal of the National

Cancer Institute, researchers note that sun exposure has been linked

to better survival in patients with melanoma. The new research

suggests that this is due, at least in part, to sunlight-related

tumors being inherently less aggressive than those not tied to sun

exposure.

 

" Our findings provide the strongest evidence to date that the better

prognosis of (sunlight-related) melanomas is not simply due to

earlier detection of these types, " Dr. Marianne Berwick told Reuters

Health.

 

Berwick, a researcher from the University of New Mexico in

Albuquerque, noted that " further studies are needed to determine how

sun exposure might reduce melanoma aggressiveness, " but said that it

could have something to do with increased production of vitamin D,

or involve an enhanced ability of cells to repair DNA damage.

 

The findings stem from a study of 528 melanoma patients who were

entered in the Connecticut Tumor Registry.

 

Sunburn, high intermittent sun exposure, self-reported skin

awareness, and solar elastosis -- a marker of sun damaged-skin --

were all linked to increased survival from melanoma.

 

Upon analysis, skin awareness was a strong predictor of better

survival, consistent with the belief that earlier detection leads to

better outcomes. However, solar elastosis, which does not relate to

detection, was found to be an even stronger predictor of increased

survival.

 

Berwick emphasized that these findings have no bearing on current

recommendations that " avoiding sun exposure reduces the risk of

melanoma. " Moreover, she added that they also do not suggest that

exposing melanomas to sunlight after they've developed will improve

survival.

 

SOURCE: Journal of the National Cancer Institute, February 2, 2005

 

 

 

 

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