I'm Shep O'Neal with the VOA Special English Health Report.

Three studies show that a drug used to treat an aggressive form of breast cancer after it has spread also can treat it earlier.

Results of the studies involving the drug Herceptin have been published in the New England Journal of Medicine. They show that in some cases it cut by about fifty percent the chance that the cancer would reappear.

The drug targets the kind of breast cancer known as H.E.R. two, or HER-two, positive. Women who produce too much of the HER-two protein have a cancer that is especially fast-growing.

Researchers say about fifteen to twenty-five percent of women with breast cancer have this kind. Doctors can remove the cancer, but it is more likely than others to return.

More than eight thousand women took part in the studies in Europe and North America. All had early HER-two positive breast cancer.

The European study followed the progress of women for up to two years. The researchers say the cancer returned in twenty-three percent of those not receiving Herceptin. Only fourteen percent of the women who received the drug experienced a return of the cancer.

The other two studies involved women who were treated with an operation, chemotherapy drugs and, in some cases, Herceptin. Thirty-three percent of the women who did not receive Herceptin had their cancer return within four years. This happened to only fifteen percent of those treated with Herceptin.

Herceptin is an antibody that attaches itself to the HER-two gene on cancerous growths. It slows or stops the cancer from growing. Treatment must continue for one year. It costs about forty-eight thousand dollars.

The studies showed possible heart-related risks. About four percent of the women who took Herceptin along with other drugs suffered serious heart problems. The rate was only about half of one percent when patients took Herceptin within one year of completing other drug treatment.

The researchers are not sure why these heart problems appeared. They say more and longer studies are needed to answer this and other questions about the drug. American doctors are being urged to treat early HER-two breast cancer with Herceptin. But some say it will take years to prove that these results can be repeated with all HER-two breast cancer patients.

This VOA Special English Health Report was written by Nancy Steinbach. Our reports are online at voaspecialenglish.com. I'm Shep O'Neal.