Association of Hypercalcemia with Tumors Producing Colony-stimulating Factor(s)

Two human malignant tumors, which we previously reported to produce colony-stimulating factors (CSFs), were found to be accompanied by remarkable hypercalcemia. A patient with a CSF-producing lower jaw cancer (squamous cell carcinoma) developed a marked granulocytosis (150,000/microliters) and hypercalcemia (more than 215 mg/dl). The tumor was successfully transplanted into nude mice, which developed marked granulocytosis (300,000/microliters) and hypercalcemia (20 mg/dl). White blood cell and serum calcium concentrations of these mice decreased promptly to normal levels when the tumor was excised. Treatment with prednisolone (1.5 mg/kg) or indomethacin (5 mg/kg) had no effect on the serum calcium level of these mice. Parathyroid hormone or prostaglandin E was not increased in the serum of the mice or in the tumor tissue. However, the mice bearing the tumor excreted extremely large amounts of calcium in their urine, and their bony tissues contained less calcium and phosphorus than controls. Moreover, histology of bony tissues of these nude mice clearly demonstrated the decrease in trabecular tissues and cortical thickness as well as remarkable activation of osteoclasts. Another patient with a CSF-producing bronchogenic squamous cell carcinoma showed mild granulocytosis and hypercalcemia. The biopsied tumor tissue was transplanted into nude mice, which developed marked granulocytosis (300,000/microliters) and also severe hypercalcemia (18 mg/dl). These results suggest the presence of a new syndrome of granulocytosis and hypercalcemia associated with CSF-producing tumors. The causal mechanism of the hypercalcemia was shown to be some humoral factor which activates osteoclasts other than parathyroid hormone. Neither prostaglandins nor osteoclast-activating factor seemed to be the cause of the hypercalcemia.