But when high-dose bisphosphonates are used to slow the spread of bone cancer, the risk rises, affecting anywhere from 1 percent to 15 percent of patients, she said.
For atypical femur (thigh) fractures, the absolute risk linked to bisphosphonates is about 1 to 5 fractures in 10,000 bisphosphonate users, she said.
Besides hip fractures, bisphosphonates prevent spine, wrist and arm fractures, Shane said.
The FDA wants the committee to consider whether current data support long-term use of bisphosphonates for treating or preventing osteoporosis. The experts also are to consider whether a time limit should be placed on their use, and if patients who need long-term therapy would benefit from a "drug holiday," meaning time off the medication.
"I am really not in favor of putting a limit on use of bisphosphonates and dictating the use of drug holidays," Shane said. "We have very little evidence to support the use of drug holidays or no drug holidays."
If the committee finds that bisphosphonates do pose a serious risk, it may suggest revising the drugs' labels to reflect these potential dangers. The labels already carry a warning about atypical femur fractures.
Dr. Nelson Watts, director of the University of Cincinnati Bone Health and Osteoporosis Center and co-author of a 2010 study on long-term use of bisphosphonates, said length of treatment should be considered on an individual basis. His study suggested patients at mild risk might discontinue drug treatment after five years for as long as no fractures occurred and no bone loss was evident. Higher-risk patients could take the drugs for 10 years and perhaps then take a "holiday" from bisphosphonates of one or two years.
"It would probably be helpful if FDA or some official organization could provide guidelines on duration of tre
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