Prevalence of bisphosphonate-associated osteonecrosis of the jaw after intravenous zoledronate infusions in patients with early breast cancer

Abstract

The definite incidence rate of bisphosphonate-related osteonecrosis of the jaws (BRONJ) is still unknown. The aim of this study was to investigate prevalence of BRONJ in a group of breast cancer patients applying the classification of the Association of Oral and Maxillofacial Surgeons 2009. Between 2000 and 2008, 63 premenopausal early breast cancer patients who were free of metastases were treated with 4 mg zoledronic acid every 6 months over 3 years as participants of a multicenter, randomized, controlled, adjuvant breast cancer medication trial. Patients were not informed about the risk of jaw necrosis. None reported tooth or jaw complaints during the breast cancer follow-up examinations. In 2010, 48 patients of this cohort were investigated concerning BRONJ by clinical and radiological examinations. No advanced stages (AAOMS 2009)were detected. However, five patients (10.4%) presented purulent (2) and nonpurulent (3) fistulas and radiological signs correlating to BRONJ stage 0. Although no case of advanced BRONJ was detected, the study revealed a high prevalence of BRONJ stage 0. This supports the need for tight cooperation between dentists and medical specialists prescribing bisphosphonates including dental pre-therapeutic and follow-up examinations. Adaption of the BRONJ classification taking account to bone exposure via fistulas is recommended. BRONJ is said to be a complication linked to high-dosage bisphosphonate therapy. The study demonstrates that even after application of zoledronate in a low-dose protocol, early BRONJ occurred. Radiological signs solely are not sufficient to confirm BRONJ; clinical signs are mandatory.