The debilitating pain that occurs in many patients with advanced malignancies is primarily produced by bone metastases. Some hematologic malignancies that involve bone, particularly the lymphomas, may be cured with systemic chemotherapy or radiotherapy, but for most patients with bone metastases, palliation is the goal of therapy. Bone scan is more sensitive than skeletal x-rays in detecting bone metastases and in assessing the overall extent of disease except in multiple myeloma, renal cell carcinoma, and thyroid cancer where many lesions are purely lytic without the new bone regeneration detected by bone scans. One important cause of hypercalcemia is metastatic bone disease. In addition, breast cancer patients may develop hypercalcemia while being successfully treated with hormonal agents, particularly estrogens and tamoxifen.
Response is associated with elevated serum calcium.
Patients who develop hypercalcemia in this setting should be treated with intravenous fluids and, in some cases, plicamycin. The hormonal agent may be withheld during the acute hypercalcemia but reinstituted once the calcium normalizes. Bone metastases usually are caused by hematogenous spread of malignant cells. Direct extension of a tumor into bone and lymphatic spread occur less frequently. Bone metastases are usually multiple.