Disease-specific risk for an osteonecrosis of the jaw under bisphosphonate therapy.

PURPOSE: Osteonecrosis of the jaw (ONJ) presents a severe side-effect of intravenous bisphosphonate (i.v. BP) treatment; yet, the pathoethiological influence of the underlying disease which indicated that treatment remains unclear.
METHODS: We studied a large register of subjects who suffered an ONJ (n = 356) under i.v. BP therapy and characterized them according to underlying diseases and BP intake. By using claims data, we analysed indications in the general public in a cohort of new users of i.v. BPs (n = 1,075) in ambulatory care. For the years 2004-2006, both data sources were compared to indirectly assess the disease-specific risk for the development of an ONJ. We further assessed disease-specific survival after treatment initiation.
RESULTS: Patients with multiple myeloma were found more often, in the ONJ register, than were treated in real life (males: 36.4% vs. 16.2%; females: 27.8% vs. 6.5%) while the proportions of patients with prostate or breast cancer were as expected, and malignancies with low survival rates were strongly underrepresented. No patients with osteoporosis were reported to the ONJ register despite accounting for 18.8% of all the treated females in the general public.
CONCLUSIONS: The pattern of diagnoses that indicated i.v. BP treatment in patients who suffered an ONJ is different from what would be expected when looking at indications in the general public. Each underlying disease may, hence, have its own inherent risk to develop an ONJ due to varying life-expectancies and overall oncological treatment regimes including the interval and type of i.v. BP application.