Introduction
The occurrence of hypercalcemia in patients with metastatic mammary cancer, especially those under treatment with sex steroids, has been recognized for a number of years. However, in the course of the past few years, this phenomenon has been observed in patients with a wide variety of malignant neoplasms, both resectable and nonresectable, and with and without demonstrable osseous metastases. The mechanisms responsible for the development of hypercalcemia are still incompletely understood. In some instances it appears that breakdown of bone by tumor growth is responsible, while in others there are indications that tumors, owing to some metabolic activity, may cause bone resorption without actually invading the skeleton.Two major aspects of this problem are considered in the exhibit. The first deals with clinical aspects of hypercalcemia, including tumor diagnoses, symptoms and signs, differential diagnosis, and general management. In addition, the importance of obtaining quantitative calcium data is stressed, and