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

Objectives: 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.

Patients And Methods: 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.

Results: 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.

Conclusion: 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.

Clinical Relevance: 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.