[Relevance of bisphosphonate long-term therapy in radiation therapy of endosteal jaw metastases].

BACKGROUND AND
PURPOSE: Bisphosphonates are used in the treatment of bone metastasis and malignant myeloma. They have been associated with osteonecrosis of the jaw (ONJ) since the year 2003. Etiology and pathogenesis of this clinical problem are not clear. The high rate of newly diagnosed cases is alarming. Based on the collective of two departments of oral and maxillofacial surgery, the results of therapy in the coincidence of systemic bisphosphonate treatment and local radiotherapy (RT) are analyzed. PATIENTS AND METHODS: In the course of 33 months (01/2003-09/2005), 63 synchronic or metachronic ONJs were seen in 42 patients as newly diagnosed episodes. Three of the 42 patients had an RT of jaw metastasis.
RESULTS: Only one patient was followed over the whole treatment period. Under RT she developed a therapy-refractory ONJ similar to osteoradionecrosis at a dose of 40 Gy. She required a wide segmental osteotomy of the mandible resulting in a total loss of masticatory function. In 39 patients with 60 ONJs without RT not a single segmental resection of the mandible was necessary.
CONCLUSION: Local RT in bisphosphonate long-term therapy seems to be a high risk constellation. As long as the pathogenesis of bisphosphonate-associated ONJ is unclear, patients subjected to RT of the head-and-neck area should be examined and dental findings should be treated.