Intravenous use of bisphosphonates to avoid pathological fracture and other bone complications in patients with advanced bone metastases may increase risk for osteonecrosis of the jaw, according to an article in the October issue of Current Opinions in Orthopaedics. Another analysis of the literature by the same author group was published in the August issue of Oncology.

When physicians treat patients with bone metastases, bisphosphonates are given intravenously; the therapy has been shown to decrease risk of skeletal complications such as fracture. Although researchers do not fully understand osteonecrosis of the jaw or its causes, the condition appears to develop in patients received bisphosphonates.

“Osteonecrosis of the jaw is not a common condition. It appears to occur in 1 percent to 10 percent of patients with advanced cancer who are on intravenous bisphosphonate therapy - a number significant enough that most medical oncologists will see patients with this condition. It is important that researchers learn why it occurs and how best to prevent or treat it,” said Catherine Van Poznak, MD, lead author and assistant professor of internal medicine at the University of Michigan Medical School.

The osteonecrosis is marked by exposed, non-healing bone. Pain, swelling and inflammation are the most common symptoms but lesions can have no symptoms. The condition typically develops months or years after the beginning of therapy with intravenous bisphosphonates.

Researchers have noted that when it occurs, it usually follows an invasive dental procedure such as an extraction where the wound does not heal in a normal fashion. To try to prevent osteonecrosis, it has been suggested that patients maximize their oral health and take care of any invasive dental work before they begin bisphosphonate therapy.

“No reported treatment has proven successful for osteonecrosis of the jaw, which means for now the focus is on prevention or alleviating symptoms once it develops. We do not know how to predict who will develop osteonecrosis of the jaw or who is most at risk,” said Van Poznak, a breast oncologist who treats patients whose cancer has metastasized to bone.

The risk for patients who take oral bisphosphonates appears to be very low. Previous studies have noted anywhere from 0.6 percent to 10 percent of patients with cancer on bisphosphonates developed the condition. Reporting is currently voluntary. The problem, Van Poznak said, is that the condition itself is poorly defined and no universal reporting mechanism exists.

To address these challenges, clinical trials are being designed to help better define the condition. These upcoming clinical trials investigating bisphosphonate therapy for advanced cancer will include monitoring for osteonecrosis of the jaw, and researchers hope to learn what causes the condition to develop.