A new study has reported that the incidence of osteonecrosis of the jaw (the death of bone in the jaw typically occurring as a result of inadequate blood supply) in breast cancer patients taking Avastin as well as bisphosphonates is only slightly higher than the incidence among patients taking bisphosphonates only. Long-term bisphosphonate treatment has been found to be associated with increased risk of osteonecrosis of the jaw. In a previous retrospective study, a 16% incidence of osteonecrosis of the jaw was found in patients receiving anti-angiogenic therapy (Avastin or Sutent) in addition to bisphosphonates for bone metastases from breast, colon, or renal cell cancers. In the present study, the incidence of osteonecrosis of the jaw was examined using data regarding 3,560 patients receiving Avastin for locally recurrent or metastatic breast cancer in two double-blind, randomized trials, as well as a large, single-arm safety study.

The overall incidence of osteonecrosis of the jaw in patients receiving Avastin was found to be 0.3% in the blinded phase of the two randomized trials and 0.4% in the single-arm study. A trend towards increased osteonecrosis of the jaw incidence was found in patients who also received bisphosphonate therapy compared to those with no bisphosphonate exposure (0.9% vs. 0.2% overall in the randomized trials; 2.4% vs. 0.0% in the single-arm study). The authors comment that the 0.3-0.4% incidence found in this large study was much lower than previously suggested in a small retrospective analysis. The 0.9% to 2.4% incidence seen in bisphosphonate-exposed patients receiving Avastin is within the 1% to 6% range reported for bisphosphonates alone. Good oral hygiene, dental exams, and avoidance of invasive dental procedures remain important in patients receiving bisphosphonates, whether or not Avastin is also used.