Parathyroid cancer.

OBJECTIVE: To review the current knowledge pertaining to the etiology, molecular pathogenesis, and management of parathyroid carcinoma, a rare presentation of primary hyperparathyroidism.

METHODS: The existing MEDLINE English-language literature was reviewed using the search terms "parathyroid" and "carcinoma" or "cancer."

RESULTS: Parathyroid cancer is a rare endocrine tumor accounting for a small proportion of cases of primary hyperparathyroidism. Recent database studies indicate increasing incidence rates. Its etiology is unknown, although numerous molecular alterations have been described, and the tumors also occur in association with germline mutations in the CDC73 gene. Most affected patients present with severe hypercalcemia; however, the diagnosis can be challenging. Complete surgical resection remains the mainstay of treatment and provides the best chance of cure, although data from small series suggest that external beam radiation may also reduce the high recurrence rates. No effective chemotherapy regimens are currently available. A significant number of patients develop recurrent disease and need additional procedures; however, long-term survival is possible with palliative surgery. Medical management of chronic and debilitating hypercalcemia with calcimimetics is often necessary and is an important adjunct in patients with recurrent and metastatic disease.

CONCLUSIONS: Further elucidation of the molecular pathogenesis of parathyroid carcinomas will enhance our understanding of etiology and behavior of this uncommon entity. Future research must be directed at identifying more effective therapies for this condition.