1794PInadequacy of current definition and staging system of Medication-Related Osteonecrosis of Jaw (MRONJ) released by AAOMS: A computed tomography study in 151 cancer and myeloma patients

Abstract Background The most largely used definition (and staging system) of Osteonecrosis of the Jaws (ONJ), more recently named Medication-Releated ONJ (MRONJ), was released by an American Association Oral Maxillofacial Surgery (AAOMS) task force. It is based on clinical features (mainly bone exposure for at least 8 weeks, or – only after 2014 - bone to be probed through a fistula) but the AAOMS is questioned by many experts. A team supported by the Italian Societies of Oral Medicine (SIPMO) and Maxillofacial Surgery (SICMF) suggested adoption of imaging tools (mainly Computed Tomography, CT) together with clinical features (Bedogni et al, Oral Disease 2012) to reach diagnosis (also in suspected cases without bone exposure, so called “Stage 0” according to AAOMS) and to evaluate real disease extension. Methods To compare the stage of MRONJ cases at the first observation time in patients receiving antiresorptive therapy (bisphosphonates, denosumab), according to two different staging systems, we reviewed charts and CT scans of cancer and myeloma patients with signs of ONJ. Results We collected data of 151 MRONJ patients in two referral centers. Disease: 73 breast cancer; 28 myeloma; 26 prostate cancer; 24 other solid tumors. The AAOMS stage was 0/I/II/III respectively in 34/38/52/27 observed cases. The SIPMO-SICMF stage was I (involvement of only alveolar bone at CT scan)/ II (extended to extralveolar bone) /III (complicated case) respectively in 48/76/27 cases. The 34 AAOMS “stage 0” cases (signs/symptoms without bone exposure) were reclassified as stage I (14) or II (20) or III (0) respectively, according to the Italian staging system. Conclusions In cancer and myeloma patients the AAOMS definition and staging system appear inadequate, potentially exposing patients to delayed diagnosis and treatment. The diagnosis and staging should be based not only on clinical data but also on the findings of the maxillofacial region CT scan, since the CT offers larger information about extent and severity of the disease. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure All authors have declared no conflicts of interest.