Lifewire: Study looks at lung cancer incidence in nonsmokers
Feb 16,2007 00:00 by Amy Winter

Smoking isn't the only cause for lung cancer. In fact, more nonsmokers are now being diagnosed with the dreaded disease than in the past.

Lung cancer kills more than 180,000 Americans each year. It has a higher death rate than breast, prostate and colon cancers combined, according to Dr. Heather Wakelee, assistant professor of medicine at Stanford.

And, according to the Feb. 10 issue of the Journal of Clinical Oncology, female nonsmokers are developing lung cancer more often than male nonsmokers. Researchers at the Stanford University School of Medicine and the Northern California Cancer Center want to figure out why.

Past research has indicated that 10 percent to 15 percent of lung cancer cases involve people who have never smoked, said Wakelee. "But when you actually try to find the hard data to show that, it's very limited."

The research team's new findings indicate that lung cancer attacks about 20 percent of nonsmoking women versus 8 percent of nonsmoking men.

"We can actually put numbers on it now," said Wakelee. "Before this, we could only estimate based on our own census."

Lung cancer is the rapid growth of unusual cells in one or both of the lungs, according to, a program started to promote national lung cancer awareness. The irregular cells multiply and clump together to form tumors, which in turn affect the lungs.

There are several causes for lung cancer:

- Smoking.

- Secondhand smoke.

- Inhaling chemicals around us, such as radon gas.

- A family history of lung cancer.

Secondhand smoke is a combination of smoke from the end of a cigarette and the smoke puffed out of a smoker's lungs. It is also known as environmental tobacco smoke, according to the Centers for Disease Control and Prevention.

Environmental tobacco smoke contains at least 250 chemicals known to be toxic or to cause cancer, the CDC site states. The general public's exposure to secondhand smoke is much higher than most people realize, it adds.

Ellen Chang, an epidemiologist at the Northern California Cancer Center and co-author of the Feb. 10 journal article, said it is hard to tell why nonsmoking women are more affected by lung cancer than men. She thinks secondhand smoke may play a part.

"Because more men smoke than women, women may be more likely to be exposed to secondhand smoke, even when they are classified as never-smokers," said Chang.

Wakelee disagreed. She said environmental toxins, such as arsenic and radon, are most likely responsible for lung cancer in nonsmokers.

The EPA Web site said radon causes 21,000 fatalities each year, with 2,900 of these deaths not linked to smoking.

The Stanford School of Medicine and Northern California Cancer Center research team hopes their results will be able to assist clinical studies dealing with the increased cases of nonsmokers diagnosed with lung cancer.

Wakelee wants the public to be more aware of lung cancer and to support the effort for research studies. She said well-known people, such as Dana Reeve, are helping to spread the word that lung cancer is not only limited to smokers.

"Nonsmoking-associated lung cancer is an increasingly important issue," Chang said, "even if only because the population of never-smokers is growing."

© Copley News Service