DALLAS -- Researchers in six cities are testing a lung cancer vaccine that has proved effective in fighting the disease.

According to doctors, it is too early to call the treatment a cure, but people who once had only months to live say it has given them their lives back.

Connie West, of Waxahachie, Texas, is walking proof of what the vaccine can do. Three years ago, West was battling aggressive lung cancer.

"It was stage-four lung cancer, and it was not good," she said.

But West is free of cancer today after participating in the trial at Baylor University Medical Center in Dallas.

As part of the trial, doctors at Baylor remove part of the patient's tumor, and then use it to develop an injection that includes a gene enabling the body to identify the cancer.

"In a number of the patients we've treated, the immune system is almost like a PacMan. It comes to the cancer once it finds a way to identify the cancer and kills the cancer cells," Dr. John Nemunaitis said.

For three of the patients injected up to six times with the vaccine, results were definitive.

"Soon after the injections, all my tumors shrank and went away," West said.

However, doctors said the majority of patients don't experience full remission.

Further trials are under way to improve effectiveness in more patients by adjusting the concentration of the vaccine formula and its delivery system.

Although West will not be considered free of cancer for two more years, she is optimistic.

"Each checkup that I've had and each checkup again has been clear," she said.

So far, about 100 people have gone through the vaccinations in Dallas.

Visit clinicaltrials.gov to volunteer for other lung cancer studies.