Treatment with two of the newer anti-cancer drugs appears to extend survival for women with breast cancer that has spread through their bodies, doctors said this week.

The use of Herceptin (trastuzumab) and Arimidex (anastrozole) together extended survival of women with metastatic breast cancer about 4.8 months, said John Mackey, associate professor of medical and experimental oncology at the University of Alberta, Edmonton, Canada.

"The combination of these two drugs leads to doubling of the time before the disease progresses, greater overall response to the drugs, a greater overall clinical benefit to the patient and perhaps longer overall survival when compared with treatment with Arimidex alone," Mackey said at the 29th annual meeting of the San Antonio Breast Cancer Conference.

In the study, sponsored by F. Hoffman-La Roche/Genentech, the marketer of Herceptin, the combination of the drugs -- both shown to be effective in treating women with advanced breast cancer -- was compared to use of Arimidex alone. Women who were treated in the trial had to be suffering from the type of cancer that was both estrogen receptor positive -- Arimidex is aimed at cancer of this type -- and over-expressed the HER2 gene -- the target of Herceptin.

"Women who received Arimidex alone had about 2.4 months without disease progression," Mackey said. "By adding Herceptin, we doubled that progression-free period."

In addition the survival of the women with the combination treatment was increased also by more than four months to about an average of 28.5 months after the diagnosis that the cancer has spread. The combination of the two drugs did not appear to markedly increase unexpected side effects.

"We look at this as a win-win situation," said Joseph Purvis, executive director of clinical research in oncology at AstraZeneca in Wilmington, Del. AstraZeneca markets Arimidex. "The combination suggests a significant improvement in progression-free survival for this unique patient population whose disease can be particularly aggressive," he told United Press International. AstraZeneca did not play a role in the study, he said.

The study evaluated 208 postmenopausal women for at least three years.

"The study appears to show that there is a little longer period of progression-free survival," Eric Winer, director of the breast oncology center of the Dana-Farber Cancer Institute in Boston, told UPI.

However, the study does not answer the question of whether the trial wound have had different outcomes if the researchers had treated the women first with Arimidex and then followed treatment with Herceptin, said Winer.

"I think that is reasonable for a clinician to start women with metastatic breast cancer with the combination or with Arimidex first and follow it with Herceptin if the patients' disease progressed," he said.