OSTEONECROSIS OF THE JAW (ONJ) IN CANCER AND MYELOMA PATIENTS. A 16-YEAR EXPERIENCE OF “RETE ONCOLOGICA PIEMONTE–VALLE D’AOSTA” CANCER NETWORK

Abstract Incidence of Medication-Related Osteonecrosis of the Jaw (MRONJ) related to cancer and myeloma treatments is yet to be assessed, with scarce epidemiologic data available from surveys of limited investigated populations. A 16-year (Jan 1 st , 2003 - Dec 31 st , 2018) regional-wide, multicenter retrospective survey was carried out through the regional database of the cancer network in North-Western Italy (Rete Oncologica di Piemonte e Valle d’Aosta), aiming to assess overall frequency, raw incidence and main characteristics of MRONJ cases among myeloma/cancer patients, over a population of 4.4 million inhabitants. Main characteristics: 691 patients (261 M, 430 F); mean age: 68 (38-90) years. Underlying diseases: metastatic breast cancer (43.8%), myeloma (24.1%), metastatic prostate cancer (19.1%), other cancer (13%). Main treatment: zoledronate (71.9%), denosumab (5.3%), other drugs/sequences (22.8%). Sites of MRONJ: mandible (63.3%), maxilla (27.7%), maxilla and mandible (9%). Median number of MRONJ cases: 44 (range: 3-66) cases/year. MRONJ occurrence was registered mostly after 12-36 months of treatment (range: 1-227 months).  As a result of cases observed in the regional cancer network centers, we estimated a raw unadjusted incidence ranging between 4.8 and 13 cases/million/year, with a mean of 9.5 cases/million/year and a median of 10.1 cases/million/year. The present, decades-long multicenter retrospective study represents un almost unprecedented collaboration between Oncology, Hematology, Oral Medicine / Surgery and Oral Maxillo-Facial Surgery units, to investigate the issue of MRONJ, in Italy. According to these data, MRONJ does not seem to be a rare event in metastatic cancer and myeloma populations, and should require the pursuit of such a multidisciplinary effort both in prevention and treatment.