San Antonio ? New research adds fresh hope that a drug that strengthens bones might also fight breast cancer.

Women who were given the drug, Zometa, as part of their initial treatment had greater tumor shrinkage and were less likely to need radical surgery, according to a preliminary study reported Thursday at a cancer conference in Texas.

In June, doctors were stunned when a big study found that Zometa — given to prevent bone loss caused by certain cancer treatments — also greatly cut the risk that cancer would recur in women who developed the disease before menopause.

Cancer specialists are eagerly awaiting the final results of a second, ongoing study testing Zometa in 3,360 women who had breast cancer after menopause — a much more common situation.

Its leaders gave a mini-report Thursday on 205 participants who had chemotherapy to try to shrink their tumors before surgery.

Those given infusions of Zometa along with chemo had a third more tumor shrinkage and as a result, were less likely to need their whole breast removed versus just the lump, said study leader Dr. Robert Coleman of the University of Sheffield in England.

Eleven percent of Zometa takers had a complete response to treatment — no evidence of cancer in their breasts or lymph nodes — versus 6 percent of women given chemo alone.

Partial studies like this are not enough to change practice, but these results are surprising and deserve further testing, said Dr. Eric Winer of the Dana-Farber Cancer Center in Boston. Such significant benefits from the bone drug before surgery “is not something I would have expected,” he said.

Winer had no role in the work or financial ties to any breast cancer drugmakers. He also is a spokesman for the American Society of Clinical Oncology, the largest group of doctors who treat cancer.

The study was sponsored by Zometa’s maker, Swiss-based Novartis AG, and the study leader consults for the company. With doctor fees, a Zometa infusion can run more than $1,200. In the study it was given every three weeks for four to six months.