Lung cancer strikes more than 170,000 people each year. It's the number one cancer killer. But a new drug may prevent the cancer from ever happening.

Only 15 percent of lung cancer patients will be cured. The rest will be given just months to live.

Preventing Lung Cancer

Marilyn Cohn was shocked when her doctor told her she had such a deadly disease.

"He said I had lung cancer, and right to my face, he said, 'You have one year to live.'"

That's news thousands of patients hear each year. Now, researchers are working to change that.

"We hope that we'll be able to prevent cancer from happening, which would be a major breakthrough," said Dr. Pierre Massion.

The drug iloprost works by boosting levels of a compound called PGI2. Lung cancer patients have low levels of PGI2.

It shrank tumors in mice by more than 70 percent. Now, it's being tested in people at risk for the disease -- those with pre-cancerous lesions like Bob Gamper.

"The good news is that yes, I'm now part of the study. The bad news is of course, is now I'm part of the study," said Gamper.

Bob smoked for 22 years.

"It was just a great mode of recreation, drinking and smoking," said Gamper. "I'm a party guy. What can I say?"

Marilyn Cohn beat the odds. Eight years later she's still doing well. If science comes through, millions of other patients may never have to deal with lung cancer.

Patients in the study take up to three pills, two times a day.

Iloprost is already F.D.A. approved for pulmonary hypertension in children, so Dr. Massion says if it holds out in studies, it could be available to patients much sooner.