Sunlight Helps Put Lung Cancer in the Shade

By Amanda Gardner
HealthDay Reporter
Tuesday, December 18, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

MONDAY, Dec. 17 (HealthDay News) -- Something as common and available as sunlight may help prevent some lung cancers, researchers say.

A new study finds that lower levels of the sun's ultraviolet B (UVB) rays are associated with a higher incidence of lung cancer across 111 countries.

Still, that doesn't mean that spending more time in the sun will ever offset the risks that come with smoking, according to the study, which is published in the January issue of the Journal of Epidemiology and Community Health.

It's also not an excuse to trade skin cancer for lung cancer.

"The problem is that people might over-interpret this and stay in the sun for hours," said Cedric Garland, study senior author, professor of family and preventive medicine at the University of California, San Diego (UCSD), and participating member at the Moores UCSD Cancer Center in La Jolla.

Too little sun isn't great either, however, since sunlight helps the skin manufacture healthy vitamin D. "It would be false prudence to stay out of the sun to prevent skin cancer and not get enough vitamin D," Garland said.

Other experts, however, feel the focus should stay on cigarette smoking as the number one cause of lung cancer.

"When you have such a strong factor as tobacco, it really weighs out all these other small influences," said Dr. Jay Brooks, chairman of hematology/oncology at the Ochsner Clinic Foundation in Baton Rouge, La. "It's a very interesting observation, but the main message is tobacco is such a strong influence in the development of lung cancer that we should concentrate on that."

More than one million people die of lung cancer worldwide each year. Cigarette smoking causes about 85 percent of lung cancers. The remaining cases are caused by exposure to secondhand smoke and a variety of other (some unknown) factors.

Sunshine is a significant source of vitamin D, as the sun's UV rays trigger synthesis of vitamin D in the skin.

Previous research, much of it by the same group, has found a strong association between breast cancer, colon cancer and other internal-organ cancers and living in latitudes with less sunlight. For example, one paper observed double the death rate from colon cancer above the U.S. Mason-Dixon line as below, leading the researchers to focus on lack of sunlight as the culprit.