Bone drugs seen helping fight cancer spread

WASHINGTON (Reuters) - A drug prescribed to prevent fractures in breast cancer patients whose tumors have spread may actually help slow the cancer itself, U.S. researchers reported on Thursday.

They said Zometa, sold by Swiss drug giant Novartis, appears to have prevented the spread of tumors to the bone.

The study, released in preliminary form ahead of a meeting of the American Society of Clinical Oncology, suggests the drug may be useful for more breast cancer patients.

"Tumor cells are continually being released from the primary tumor," Dr. Rebecca Aft of Barnes Jewish Hospital and Washington University in St. Louis, said in a statement.

"It is thought that the bone marrow harbors these cells and that these cells are likely to evolve into metastatic disease. We think that zoledronic acid changes the bone marrow so that cancer cells are unable to lodge there."

Full details of the study will be released June 3 at the ASCO meeting in Chicago.

Zometa, known generically as zoledronic acid, is in a class of drugs known as bisphosphonates. They are usually prescribed to treat or prevent osteoporosis, but Zometa is mainly used to strengthen the bones of cancer patients whose tumors have spread to the bone.

Breast and other cancers commonly spread to the bone and patients can be crippled by the pain and fractures that result.

Aft's team studied 120 women with stage 2 or stage 3 breast cancer, which has spread into lymph nodes or other areas near the breast. Some got intravenous infusions of Zometa every three weeks for a year, while others did not.