Should Vitamin D Level be Measured Before Denosumab inPatients with Castration-Resistant Metastatic Prostate Cancer to Prevent Hypocalcemia?

Abstract

Objectives: Denosumab reduces skeletal related events in castration-resistant metastatic prostate cancer (CRMPC)with bone metastases.It is recommended to give calcium and vitamin D to prevent hypocalcemia after denosumab.There is no recommendation to check vitamin D and the specific level of vitamin D that should not be given beforedenosumab. We aimed to show that the rate of hypocalcemia is high even in vitamin D deficiency alone in the absenceof other risk factors for hypocalcemia and can be reduced by checking vitamin D before the administration or by adjust ing the dose of denosumab according to the vitamin D, which are not included in denosumab product information (PI). Methods: We retrospectively analyzed 40 CRMPC patients who received subcutaneous injections of 120 mg denosumab. Results: 28 patients had vitamin D deficiency before treatment. Patients with vitamin D deficiency had a higher rate ofhypocalcemia (87.5% vs 16.6%). Hypocalcemia was significantly higher in patients with vitamin D deficiency (p:0.001).In patients with vitamin D deficiency, 87.5% grade1, 8.3% grade 2 and 4.1% grade 3 hypocalcemia developed. Conclusion: Vitamin D should be checked before treatment to prevent denosumab-related hypocalcemia. New studiesshould be planned for this recommendation to be in the denosumab PI.