Comparison of the Effectiveness and Hypocalcemia Risk of Antiresorptive Agents in Patients with Hypercalcemia of Malignancy.

Backgruound: Hypercalcemia of malignancy (HCM), a major metabolic complication of cancer, is often managed with bisphosphonates (BP) and, increasingly, with denosumab. We aimed to compare the effectiveness and safety of denosumab with that of BP, with or without calcitonin, in treating HCM.

Methods: This retrospective cohort study was conducted at a tertiary hospital from 2017 to 2022 and included 317 patients treated for HCM. Participants were divided into three treatment groups: denosumab, intravenous (IV) BP only, and IV BP combined with calcitonin. The primary outcomes measured were changes in calcium levels and the incidence of hypocalcemia. Analysis of covariance was used to adjust for age, sex, body mass index, creatinine level, type of malignancy, and the use of furosemide and steroids.

Results: The mean participant age was 65 years, and 37.5% were female. After adjustment, both denosumab and IV BPs were found to effectively lower calcium levels. Denosumab led to a decrease of 2.0 mg/dL (-15.9%), while IV BP alone resulted in a reduction of 1.8 mg/dL (-13.9%). The largest reduction, of 2.7 mg/dL (-20.9%), occurred with IV BP and calcitonin. Both denosumab and IV BP+calcitonin yielded their lowest calcium levels within 48 hours, whereas the IV BP only group reached a nadir within 72 hours. Despite these differences in treatment effectiveness, hypocalcemia occurred significantly less frequently in the denosumab group compared to the other groups.

Conclusion: Denosumab and IV BP were similarly effective in reducing calcium levels. However, IV BP combined with calcitonin yielded a more rapid and pronounced decrease.