Hypercalcemia and treated breast cancers: the diagnostic dilemma

The relationship of hypercalcemia with cancer is well described in the literature. Breast cancer is the commonest malignancy associated with hypercalcemia; the detection of hypercalcemia in these patients usually signifies metastatic disease and is associated with a poor prognosis. However, the treating oncologist should keep in mind that a strong correlation exists between breast cancer and primary hyperparathyroidism. We present a case of a patient of treated breast cancer who, in the absence of metastatic bone disease, developed hypercalcemia due to hyperparathyroidism secondary to a parathyroid adenoma.