Osteonecrosis of the jaw in patients with metastatic breast cancer: ethnic and socio-economic aspects.

Bisphosphonate therapy is an important adjunct to the treatment of patients with bone metastasis. Osteonecrosis of the jaw (ONJ), a complication related to bisphosphonate therapy, is reported in up to 7% of patients with metastatic breast cancer. The objective of this study was to define the prevalence and to identify risk factors associated with development of ONJ in a predominantly low socio-economic population. Medical records of patients with a diagnosis of metastatic breast cancer with bone metastasis seen between 2002 and 2007 were reviewed. All patients received a minimum of four infusions of zolendronic acid. Data on demographics, insurance status, tobacco use, concurrent therapy, body mass index, and number of zolendronic acid infusions were analyzed. Of the 110 patient analyzed, 10 developed ONJ (9%) with the mean number of zolendronic acid infusions in patients with ONJ of 22.9 +/- 17. ONJ was seen more frequently in Caucasian than in African Americans patients (15% versus 2%; p = 0.019). ONJ was associated with older age at diagnosis of metastatic breast cancer (p = 0.02), tobacco use (p = 0.049), but was not associated with SES or duration of therapy. After adjusting for SES, Caucasian patients were 9.1 times more likely to have ONJ when compared with African American patients. (95% CI 1.03-81.7). Our results suggest an increase prevalence of ONJ in Caucasian breast cancer patients. However, as our study population is small, additional studies to confirm this finding are needed.