Washington, Jan 20 : University of Oklahoma researchers have developed a heat therapy, which when used with chemotherapy destroys large breast cancer tumours.

The new treatment reduced the need for mastectomies by almost 90 percent.

"This therapy is a major advancement for women with later stage breast cancer," said William Dooley, M.D., a researcher at the OU Cancer Institute and the director of surgical oncology at OU Medicine.

"Right now, most patients with large tumors lose their breast. With this treatment along with chemotherapy, we were able to kill the cancer and save the breast tissue," he added.

The research team is working on a treatment called Focused Microwave Thermotherapy.

This technique uses a modified version of the microwave technology behind the "Star Wars" defense system.

They tested the therapy on tumours that were an inch to an inch and a half in size. These large tumours usually require mastectomies.

When researchers used the heating therapy within two hours of patients receiving chemotherapy, the tumour was more susceptible to the chemotherapy and shrunk rapidly.

The percentage of patients needing mastectomies was reduced from 75 percent to 7 percent.

"The trial was very successful. We were able to completely reverse those odds," Dooley said.

"We redesigned the machine and will begin clinical trials this year to determine whether the therapy works on tumors that are larger than one and a half inches and smaller than 5 inches in size," he added.

The study appears in Annals of Surgical Oncology.