Bisphosphonates for Cancer Treatment May Raise Stroke Risk

Powerful <"">bisphosphonate medications used in cancer treatments, including Aredia and Zometa, have been linked to an increased risk for stroke and atrial fibrillation (irregular heartbeat), US News just reported, citing an emerging study.

Bisphosphonates, sold under the brand names Actonel, Actonel+Ca, Aredia, Boniva, Didronel, Fosamax, Fosamax+D, Reclast, Skelid, and Zometa, are commonly used in tablet form to prevent and treat osteoporosis in post-menopausal women. Stronger forms of bisphosphonate drugs are used in the management of advanced cancers that have metastasized to the bone, where the disease often causes bone pain and possibly even fractures. When bisphosphonates are given in cancer chemotherapy, the drugs are given intravenously (IV) in higher doses and usually for longer periods to minimize pain, said US News, and to stave off the damage that the cancer causes to the bone.

Originally, generally prescribed for osteoporosis treatment, “In the 1990s, it was discovered that they had a rather miraculous effect in terms of either treating or preventing metastases to bones from certain cancers,” said Dr. James Goodwin, senior author of a paper appearing online in the Journal of Clinical Oncology, quoted US News. Goodwin is also director of the Sealy Center on Aging at the University of Texas Medical Branch in Galveston.

“These are expensive drugs—several thousand dollars per injection—but they do have a benefit of preventing bone loss and decreasing the number of bone fractures in people with cancer, which is very significant,” said Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Clinic Foundation, quoted US News. “If you break a femur or a hip with metastatic cancer, it’s devastating to you,” Dr. Brooks added.

In cancer treatment, bisphosphonates (zoledronic acid) are administered via IV and at much stronger doses—ten times higher—than when prescribed to noncancer patients who receive the drug in pill form, explained US News.

Bisphosphonates have already been linked to other risks such as, said US News, significant bone and muscle pain, allergic responses, and increased risks for a rare fracture of the thigh bone. Some cancer patients have also reported a serious side effect called osteonecrosis of the jaw (ONJ) or dead jaw syndrome. Well over 500 lawsuits filed in federal courts by alleged victims of this Zometa side effect have been consolidated in two multidistrict litigations in Tennessee federal court and New Jersey state court against Zometa maker Novartis Pharmaceuticals.

Goodwin and his team looked at Medicare data on some 7,000 men and women aged 65 or over who received a cancer diagnosis and were also taking IV bisphosphonates, said US News, noting that this group was compared with a 14,000-member control group of cancer patients not taking bisphosphonates. The team found that those receiving IV bisphosphonates saw an increased risk for atrial fibrillation and stroke by about 30 percent, US News reported.

Of note, Zometa lawsuits allege that Novartis failed to adequately warn that Zometa can cause ONJ, a disorder in which the bone tissue in the jaw fails to heal after minor trauma such as a tooth extraction, causing the bone to be exposed. Exposure can eventually lead to infection and fracture and may require long-term antibiotic therapy or surgery to remove dying bone tissue.

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