(CBS/AP) Breast cancer doctors hoped the bone drugs they prescribed patients would prevent complications from the disease. Seven years later, the doctors saw the bone drugs did in fact improve breast cancer survival in women.
What's especially impressive is that the women were treated only once every six months for three years.
"The benefit persists" long after treatment ends, said Dr. Michael Gnant of Austria's Medical University of Vienna, who presented his research last week at the San Antonio Breast Cancer Symposium.
Gnant's study showed women who received the bone drug Zometa were 37 percent less likely to die than women who didn't. That means that 4 to 5 more women with breast cancer out of every 100 were alive seven years later because of the treatment.
Some cancer specialists are now calling for Zometa to be offered to all patients like those in this study - younger women forced into early menopause by hormone-blocking cancer treatments.
"It's a new standard of care," said Dr. James Ingle, a Mayo Clinic breast specialist.
Bone drugs called bisphosphonates - sold as Fosamax, Boniva and Actonel - have long been prescribed as daily pills for treating osteoporosis. Zometa, made by Swiss-based Novartis AG, is given intravenously to treat cancer that has spread to the bone.
Gnant's hopes were raised that the drug could do more in 2008, when he reported that it lowered the risk of cancer recurrence in a study of 1,800 premenopausal women with early-stage breast cancer.
After years of follow-up, Gnant and fellow researchers saw that Zometa not only helped keep cancer from coming back, but it also improved survival. There were 33 deaths among women taking Zometa and 49 among those who weren't.
That large benefit is comparable to many chemotherapy treatments. Researchers think because Zometa strengthens bones, it's tougher for cancer to spread there and the drug may also prevent cancer cells or microscopic tumors from spreading.
Zometa's side effects were mostly bone and joint pain and fever. Doctors saw no cases of jawbone decay, a serious side effect linked to bisphosphonates. Zometa costs more than $1,000 in the U.S., though the price may drop when its U.S. patent expires in 2013.
The bone drug proved disappointing last year in a large study last of older postmenopausal women, who account for three-fourths of all breast cancers. But there's still hope for the oldest patients.
"They benefitted substantially as long as they were well past menopause," said Dr. Peter Ravdin, director of the breast cancer program at the UT Health Science Center in San Antonio.
Other studies reported at the conference this week strengthen the view that Zometa works best in women with little estrogen. Ravdin said that signals the emergence of a consistent treatment pattern.