A retrospective study assessing the incidence, risk factors and comorbidities of pamidronate-related necrosis of the jaws in multiple myeloma patients.

BACKGROUND: Bone necrosis of the jaws is a newly recognized complication associated with the use of bisphosphonates. The true incidence of this complication is unknown and the pathophysiology is controversial. The purpose of this study was to determine the incidence of jaw necrosis among a homogeneous population of multiple myeloma patients receiving the bisphosphonate pamidronate, to investigate risk factors and comorbidities that increase the risk and to characterize the radiographic changes on conventional dental radiographs in terms of type and frequency.
MATERIALS AND METHODS: The study was a retrospective review of medical and dental charts and databases in the medical oncology and dental departments at Princess Margaret Hospital, a tertiary cancer centre in Toronto. Two patient sample sizes were used, n = 655 for assessment of the incidence and n = 120 for analysis of the risk factors and comorbidities.
RESULTS: The incidence was estimated at 3.2% (95% confidence interval). The following risk factors were found to be statistically significant: longer duration of pamidronate therapy (P < 0.001), dental extractions (P < 0.001), cyclophosphamide therapy (P < 0.014), prednisone therapy (P < 0.014), erythropoietin therapy (P = 0.006), low hemoglobin levels (P < 0.001), renal dialysis (P < 0.016) and advanced age (P < 0.001). Radiographic changes produced by the necrotic bone were less evident than the clinically exposed bone.