Risk factors for development of hypocalcemia in patients with cancer treated with bone-modifying agents

Abstract

Background: This retrospective analysis describes the prevalence of and risk factors associated with the development of hypocalcemia in patients with cancer receiving bone-modifying agents (BMAs) as supportive care. Patients and Methods: Patients with cancer treated with an intravenous or subcutaneous BMA, including pamidronate, zoledronic acid, or denosumab, at a tertiary care/safety net hospital in 2005 through 2015 were included in this retrospective review. We reviewed the medical records for predictive clinical and laboratory parameters and for patient outcomes. Results: A total of 835 patients with cancer received at least one dose of a BMA during the specified time frame; 205 patients (25%) developed hypocalcemia of CTCAE grade $1 within 8 weeks of BMA initiation, 18 of whom (8.8%) had grade $3, and 3 patients died as a result. Multivariate analysis showed that patients with hematologic malignancy (odds ratio [OR], 1.956; P5.025), bone metastases (OR, 2.443; P5.017), inpatient status (OR, 2.592; P,.001), and deficient baseline vitamin D levels (OR, 2.546; P,.023) were more likely to develop hypocalcemia. Hypercalcemia before BMA administration (OR, 0.474; P5.032) was protective. Conclusions: Certain patient populations, including those with hematologic malignancies and/or bone metastases, warrant closer monitoring of calcium levels while receiving BMAs because of the high rate of hypocalcemia. Low pretreatment vitamin D levels are associated with the development of hypocalcemia. These data support close monitoring of calcium levels in patients with cancer receiving BMAs, in addition to adequate repletion of vitamin D before initiation of BMAs when possible.