Bisphosphonate-refractory HCM — SCE Medical Oncology MCQ

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ModerateBreast CancerBisphosphonate-refractory HCMSCE Medical Oncology

A 60-year-old woman with metastatic breast cancer develops malignant hypercalcaemia. She has been treated with IV zoledronic acid but calcium remains elevated at 3.2 mmol/L after 48 hours. What is the next step?

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Correct answer: E — Denosumab 120 mg SC — RANKL inhibition can be effective in bisphosphonate-refractory hypercalcaemia of malignancy

Bisphosphonate-refractory hypercalcaemia occurs in approximately 30-50% of cases. Denosumab (120 mg SC) can rescue bisphosphonate-refractory HCM because it works through a different mechanism (RANKL inhibition vs direct osteoclast toxicity). Denosumab typically reduces calcium within 4-10 days. Calcitonin provides rapid but transient bridge therapy (tachyphylaxis within 48 hours). Ongoing management requires effective anti-cancer treatment. Dialysis is reserved for life-threatening cases with renal failure.

Reference: ESMO 2024 Oncological Emergencies; Hu et al JCO 2014; BNF Denosumab