OKLAHOMA CITY - Scientists at the University of Oklahoma's Cancer Institute said Friday they have found a way to isolate cancer stem cells in tumors so they can be targeted and killed.

But the scientists cautioned that a new drug capable of preventing cancer from recurring is up to 10 years away from availability to the public and that it is premature to calculate how effective the new treatment will be.

"We're certainly not trying to say we have a cure," said Dr. Courtney Houchen, a cancer prevention researcher at the OU Cancer Institute. "It would be premature to tout the efficacy."

Houchen said treatments on laboratory animals produced a 50 percent to 90 percent reduction in cancerous tumors and eliminated tumors entirely in some animals.

"It seems to be very effective," Houchen said.

Following years of research, Houchen and other OU researchers discovered that a particular protein appears only in stem cells. By targeting those cells, physicians would be able to stop cancer from returning.

"We think that isolation of the stem cell...is a major breakthrough," Houchen said.

Researchers focused their research on pancreatic cancer but a new cancer stem cell treatment could be used to fight most any cancerous tumor, Houchen said. Treatments could conceivably be taken orally or injected directly into a tumor, he said.

Dr. Robert Mannel, chairman of the institute, said the key to developing a new cancer drug is adequate funding to cover research and development costs. Mannel said some drugs cost hundreds of millions of dollars to develop and test before they receive government approval and become available to the public.

Researchers expect to have initial testing completed to begin the first phase of clinical trials within five years. If successful in human trials, the new compound is expected to be available to the public within 10 years.

"Our goal is to certainly shorten that timeline," Mannel said.

Current cancer therapies generally do not target stem cells in tumors, allowing them to wait until after chemotherapy and radiation treatments to begin dividing. Researchers believe those stem cells are often responsible for the return of cancer after treatment.

Identifying the stem cell marker enables researchers to develop new therapies that can target adult cancer stem cells, which scientists said play a major role in the start, growth and spread of cancer and its return following conventional treatments.

Currently, 40 percent of patients who receive a cancer diagnosis will die of the disease within 10 years, Mannel said.

"We're approaching cancer in a different way," Houchen said. "All of this is relatively new."