Osteoporosis drugs linked to esophageal cancer

If you are an avid follower of health related news, you may have recently read that a new study suggests that use of anti-osteoporosis drugs, known as bisphosphonates, may drastically increase the risk of esophageal cancer, which kills about 15,000 people in the United States each year.

The study was conducted by Dr. Jane Green and colleagues from the University of Oxford's Cancer Epidemiology Unit and is currently published in the Sept 2010 issue of British Medical Journal.

The researchers found use of oral bisphosphonates was associated with an elevated risk of esophageal cancer after comparing data from about 15,000 patients who were diagnosed with either esophageal, stomach, or colorectal cancer, who were registered in the UK General Practice Research Database, with data from five times as many controls.

Specifically, Dr. Green found patients who were given more than 10 prescriptions or took oral bisphophonates for more than five years were twice as likely as controls to be diagnosed with esophageal cancer. In other words, these drugs could cause esophageal cancer in two out of 1000 patients on the medications.

Bisphosphonates are commonly used to treat osteoporosis and other bone diseases. Food consumer reported earlier that these anti-osteoporosis drugs are also linked with an increased risk of serious atrial fibrillation and femoral insufficiency fractures.

The U.S. Food and Drug Administration has been aware of prior studies that have linked oral bisphosphonates with some adverse effects since 2007, at the very latest.

On May 3, 2007, a study published in the New England Journal of Medicine found two drugs based on bisphosphonates named Reclast and Fosamax were associated with increased risk of serious atrial fibrillation in older women with osteoporosis. But the FDA said the difference in the risk found between bisphosphonate users and non-users was not significant.

Later, the FDA analyzed the risk based on trial information from manufacturers of alendronate, ibandronate, risedronate and zoledronic acid and found all but one study involving zoledronic acid were not associated with increased risk of atrial fibrillation.  

It should be noted that all trials lasted no more than three years, which means that no one knows for sure what will happen to the osteoporosis patients taking the drugs on a continuing basis for longer than that.

On Jan 7, 2008, the FDA posted some postmarket drug safety information for healthcare professionals alerting them to some side effects of oral bisphosphonates - severe and sometimes incapacitating bone, joint, and or muscle (musculoskeletal) pain.  

The agency said later in June 2009 that the issue has been addressed in product labeling. The concerned bisphosphonates are marketed as Actonel, Actonel+Ca, Aredia, Boniva, Didronel, Fosamax, Fosamax+D, Reclast, Skelid, and Zometa.

Abrahamsen B. from Copenhagen University Hospital Gentofte published an article in the July 2010 issue of Current Opinion in Rheumatology saying that the risk of harm caused by bisphosphonates is low compared to the risk of classical osteoporotic fractures.

Abrahamsen acknowledged, however, that the trials of concern have their limitations and clinical case control studies are still recommended to further ascertain risk.

By Jimmy Downs and editing by Rachel Stockton