Calcium and cancer

Tumors cause disturbances in calcium homeostasis less frequently than they cause abnormalities in bone metabolism. The bone abnormalities include osteolytic metastases and osteoblastic metastases which lead to increased bone formation. Cancer is associated with hypocalcemia more frequently than hypercalcemia, although hypercalcemia is more likely to cause symptoms. Increased bone resorption is the major mechanism of malignant hypercalcemia. Recent advances in our knowledge of normal bone metabolism and calcium regulation have led to new concepts of the mechanisms of disturbances in calcium homeostasis in cancer patients. Future progress in this area depends on clarification of the cellular and molecular mechanisms of bone resorption in cancer. Major therapeutic advances will depend on the development of treatment regimens designed to oppose pathogenetic mechanisms.