Assessment of renal toxicity and osteonecrosis of the jaws in patients receiving zoledronic acid for bone metastasis

Background: Bisphosphonates (BP) decrease the incidence of skeletal related events among cancer patients with bone metastases from solid tumors and multiple myeloma. Renal safety and osteonecrosis of the jaws (ONJ) are two major concerns of toxicity. Information about safety of using BP beyond 2 years is scarce. Materials and methods: Patients receiving zoledronic acid (ZA) at the time of the study were reviewed. Serum creatinine levels (SCL) were collected at three different moments: before the start of BP (baseline), at the time of analysis (final), and the highest SCL during the treatment (highest). Oral examination was carried out in every patient. Separated analysis was made for patients on BP for > 2 years. Concomitant risk factors for both renal toxicity and ONJ were evaluated. Results: Sixty-seven patients were included. Median time of BP was 22 months, with 22 patients receiving BP for > 2 years. Median baseline and final values of SCL were 0.71 mg/dl and 0.70 mg/dl, respectively (P = 0.121). Median highest SCL during treatment was 0.82 mg/dl (P < 0.0001). A notable increase in the SCL was observed in six of the 67 patients (9%), four of them receiving BP for > 2 years (P = 0.085). ONJ was also diagnosed in six patients, four of them in the group of prolonged BP treatment. Conclusion: ZA showed to be safe with a low rate of reversible renal toxicity. Patients receiving BP should be monitored carefully for renal toxicity and ONJ, especially those with exposure to BP beyond 2 years.