HYPERCALCEMIA IN PATIENTS WITH METASTATIC RENAL-CELL CARCINOMA - EFFECT OF NEPHRECTOMY AND METABOLIC EVALUATION

Purpose: The role of nephrectomy in the management of hypercalcemia in metastatic renal carcinoma is not known. Hypercalcemia in patients wi th renal cell carcinoma frequently mimics primary hyperparathyroidism and has been attributed to tumor secretion of parathyroid hormone rela ted protein. We determined the role of cytoreductive surgery in patien ts with metastatic renal cell carcinoma and hypercalcemia, identified factors that predict patient benefit from surgery, and evaluated the m echanisms of hypercalcemia in these patients. Materials and Methods: A total of 15 patients with metastatic renal cell carcinoma and hyperca lcemia underwent metabolic and laboratory evaluation followed by nephr ectomy. Postoperatively they were followed for changes in serum calciu m levels. We selected 18 normocalcemic patients with metastatic renal cell carcinoma and 4 normocalcemic patients without renal cancer to se rve as control groups for survival and parathyroid hormone related pro tein expression. Results: A decrease in serum calcium corrected for al bumin occurred in 9 of 11 patients at 1 to 4 weeks after nephrectomy a nd in 7 of 12 patients at 5 to 16 weeks after nephrectomy. Clinical ev aluation supported a parathyroid hormone related protein mechanism of hypercalcemia in 5 of 8 patients. Two patients had evidence of local o steolytic hypercalcemia and 1 had prostaglandin mediated hypercalcemia . Conclusions: Nephrectomy temporarily ameliorated hypercalcemia in a subgroup of patients with metastatic renal cancer and hypercalcemia. P arathyroid hormone related protein expression was commonly found to be associated with hypercalcemia. Nonparathyroid hormone related protein mechanisms of hypercalcemia in renal carcinoma may be more common tha n previously thought.