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Cancer risk is reported for bone drugs

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 official reported Thursday in a letter to the New England Journal of Medicine.

Diane K. Wysowski of the drug risk assessment division said the FDA has received 23 reports of the cancer developing in patients taking Fosamax, manufactured by Merck & Co. Eight of the patients died.

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

More than 2 billion prescriptions have been written for the drugs since their introduction in 1995.

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

Wysowski recommended that physicians not prescribe the drugs to patients who have esophageal problems.

In a separate report Thursday in the Journal of the American Dental Assn., Parish Sedghizadeh of the USC 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 -- death of the bone -- is known to occur in 1% to 10% of cancer patients taking intravenous bisphosphonates to combat bone weakening brought on by chemotherapy. It is rarely observed in patients taking oral forms of the drug, however.

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Some people immediately dismissed his findings, arguing that the widespread use of the drugs would have already 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 R. Recker, director of the Osteoporosis Research Center at Creighton University in Omaha and president of the National Osteoporosis Foundation. “The study design and sample size were simply inadequate to make any conclusions.”

Both the American Society for Bone and Mineral Research and the American Dental Assn. have recently conducted comprehensive reviews of the risks of osteonecrosis associated with oral bisphosphonates, added Dennis Black, a professor of epidemiology and biostatistics at UC San Francisco. They concluded “that the risk is somewhere between 1 in 10,000 and 1 in 100,000, and it is not clear that this is increased by bisphosphonates,” he said.

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thomas.maugh@latimes.com


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