TUESDAY, Jan. 19 (HealthDay News) -- Not only does cigarette smoke cause lung cancer, it worsens the disease by increasing lung inflammation, U.S. researchers have found.

The team at the University of California, San Diego School of Medicine conducted tests on mice with early lung cancer lesions and found that those repeatedly exposed to tobacco smoke developed larger tumors -- and developed tumors more quickly -- than those that weren't exposed to tobacco smoke. Lung tissue inflammation was the major contributing factor.

The findings, published Jan. 19 in the journal Cancer Cell, offer definitive proof that lung inflammation caused by chronic exposure to tobacco smoke promotes lung cancer growth, the researchers said.

In addition, the study results establish new lung cancer models, provide new information about the development and growth of lung cancer, and suggest that anti-inflammatory drugs may prevent or slow lung cancer progression.

"We've shown for the first time that tobacco smoke is a tumor promoter -- not only a tumor initiator -- and that it works through inflammation," study leader Michael Karin, professor of pharmacology and pathology, said in a university news release.

More information

The U.S. National Cancer Institute has more about lung cancer.