Hypocalcaemia--an unusual complication of successful chemotherapy for metastatic breast cancer

Three cases of metastatic carcinoma of the breast are described in patients who presented with hypercalcaemia. They achieved an excellent regression of their disease with combination chemotherapy but despite this they clinically deteriorated. Investigation showed them to be hypocalcaemic due to temporary hypoparathyroidism. Correction of their serum calcium resulted in good symptomatic relief. The possible mechanisms for these changes are discussed and we feel that this unusual complication of successful chemotherapy should be remembered when patients fail to improve symptomatically despite a good disease response.