"It's monumental," Dr. Vincent Tuohy said Tuesday from Ohio. Tuohy, who spearheaded the eight-year study along with a team at Cleveland Clinic's Lerner Research Institute, said the vaccine targets a protein found in breast tumours and could prevent the disease with a single dose.

"What we believe we have here is a vaccine that would, someday, be used to prevent breast cancer in adult women the way vaccines have prevented childhood diseases," he said. "What we can do to breast cancer was what was done to polio and I sound preposterous, but that's what we've been working for.

During his research, which is to appear in the journal, Nature Medicine, on June 10, Tuohy vaccinated genetically cancer-prone mice — half with the vaccine containing alpha-lactalbumin and half with a vaccine that did not contain the substance. After 10 months, none of the mice vaccinated with the antigen developed breast cancer, while all the other mice did.

"It was a clear yes or no and I was delighted. We've shown a strategy for vaccinating before the cancer develops and no one's done that — and we've done it in a simple way," Tuohy said.

The scientist believes testing on women would "translate reasonably closely" because the targeted protein is found in high levels in both mouse and human tumours.

Depending on results, the second group of patients tested would be women with a high risk of developing breast cancer and planning to have a mastectomy to lessen their chances.

These groups would be monitored for three years before vaccine is tested on another set of women.