Cancer risk tied to drugs taken for bone health

The family of bone-strengthening drugs called bisphosphonates — best known by the brand names Fosamax, Actonel and Boniva — pose a small risk of causing esophageal cancer, a Food and Drug Administration (FDA) official reported Thursday in a letter to the New England Journal of Medicine.

Diane Wysowski of the FDA's division of drug-risk assessment said the agency has received 23 reports of the cancer developing in patients taking Fosamax, manufactured by Merck. Eight of the patients died.

European and Japanese authorities, she added, have received an additional 21 reports of cancers involving Fosamax and six involving Proctor & Gamble's Actonel or Roche's Boniva.

To put that into perspective, more than 2 billion prescriptions have been written for the drugs since their introduction in 1995.

The drugs were known to cause esophagitis, an inflammation of the lining of the esophagus or throat, which is why patients are told to remain upright for a half-hour after taking the drugs. That inflammation might be a precursor of cancer.

Wysowski recommended that physicians not prescribe the drugs to patients who have problems with their esophagus.

In a separate report in the Journal of the American Dental Association, Dr. Parish Sedghizadeh of the University of Southern California School of Dentistry reported that he had observed nine cases of osteonecrosis of the jaw among 208 patients taking oral bisphosphonates, an unusually high incidence.

Osteonecrosis of the jaw, involving the death of bone, is known to occur in 1 to 10 percent of cancer patients taking intravenous bisphosphonates to combat bone weakening from chemotherapy. It is rarely seen in patients taking oral forms of the drug, however.

Critics dismissed Sedghizadeh's findings, saying the widespread use of the drugs would have revealed such a high incidence of a disabling side effect.

"The most important criticism is that the sample size was only 208 patients," said Dr. Robert Recker of the Osteoporosis Research Center at Creighton University in Omaha, Neb.

"The study design and sample size were simply inadequate to make any conclusions," said Recker, president of the National Osteoporosis Foundation.

The American Society for Bone and Mineral Research and the American Dental Association have reviewed the risks of osteonecrosis associated with oral bisphosphonates, said Dr. Dennis Black of the University of California, San Francisco. They put the risk at "somewhere between one in 10,000 and one in 100,000, and it is not clear that this is increased by bisphosphonates," he said.