A different schedule of zoledronic acid can reduce the risk of the osteonecrosis of the jaw in patients with multiple myeloma.

Osteonecrosis of the jaw (ONJ) is a reported complication of bisphosphonate use. The incidence ranges between 6 and 13% and seems to be higher in people treated with zoledronic acid (ZA) than with pamidronate. We retrospectively evaluated the incidences of ONJ and skeletal-related events (SRE) in 106 patients with multiple myeloma divided in two groups according to the schedule of administration of bisphosphonates: 51 received monthly administrations until tolerated (group A, standard schedule), 55 were treated monthly during the first year and then every 3 months (group B, reduced schedule). The incidence of SRE was similar (15.1 per 100 person years in group A and 17.7 in group B). ONJ occurred in seven patients, six in group A and one in group B (P=0.049). The risk of ONJ was eight-fold lower with the reduced schedule than with the standard schedule. The only significant risk factor for ONJ was the type of bisphosphonate (P=0.006). The incidence of ONJ was significantly higher with ZA than with pamidronate + ZA (9.1 vs 1.6 per 100 person-years). No ONJ was observed in patients treated only with pamidronate. A reduced schedule of ZA may be safer than the standard schedule while maintaining anti-resorptive efficacy.