Description: While smoking marijuana is never good for the lungs, the active ingredient in pot may help fight lung cancer, new research shows.

Harvard University researchers have found that, in both laboratory and mouse studies, delta-tetrahydrocannabinol (THC) cuts tumor growth in half in common lung cancer while impeding the cancer's ability to spread.

The compound "seems to have a suppressive effect on certain lines of cancer cells," explained Dr. Len Horovitz, a pulmonary specialist at Lenox Hill Hospital in New York City.

According to the researchers, THC fights lung cancer by curbing epidermal growth factor (EGF), a molecule that promotes the growth and spread of particularly aggressive non-small cell lung cancers. "It seems to go to (EGF) receptor sites on cells and inhibit growth," said Horovitz, who was not involved in the study.

The findings are preliminary, however, and other outside experts urged caution.

"It's an interesting labor