The vast majority of cases of hyperparathyroidism are due to benign parathyroid tumors or parathyroid hyperplasia. The number of reported cases of parathyroid cancer in the medical literature is small, perhaps less than 500 cases. The reported incidence of parathyroid cancer is generally less than 1% of all cases of hyperparathyroidism. The etiology, or reasons why patients develop parathyroid cancer, are unknown. Patients with end-stage renal disease, who are predisposed to parathyroid hyperplasia, may have an increased incidence of parathyroid cancer Parathyroid carcinoma in patients with chronic renal failure on maintenance hemodialysis. Surgery. 1996 Nov;120(5):897-901. Although levels of circulating PTH may be high in patients with renal failure or parathyroid cancer, it is usually not possible to distinguish between these possibilities clinical prior to operative exploration. Patients with parathyroid cancer may be expected to present with more extreme elevations in calcium and circulating PTH, alkaline phosphatase, and often may have a palpable neck mass.
An aggressive surgical approach to the treatment of parathyroid cancer has been advocated, with exploration of all 4 parathyroid glands and hemithyroidectomy on the side of the lesion. Postoperatively, if the levels of PTH remain elevated, re-exploration of the neck is indicated. Some patients may benefit from localization studies prior to re-operation.
Radiotherapy has generally not proven to be effective for the treatment of parathyroid cancer, but in some centers, positive experiences have been reported, however these are not randomized studies, which are difficult to do due to the low numbers of patients that present with this disease. Parathyroid carcinoma--the Princess Margaret Hospital experience. Int J Radiat Oncol Biol Phys. 1998 Jun 1;41(3):569-72. Similar comments apply to chemotherapy, which has not been widely effective in a small number of patients with aggressive disease.
In some patients management of severe hypercalcemia can be challenging, and require administration of bisphosphonates, calcitonin, mithramycin, gallium nitrate, or an experimental agent such as a calcimimetic agent.
The presentation of patients with parathyroid cancer usually overlaps that of patients with hyperparathyroidism.
For a general overview of this disease, see Clinical review 122: Parathyroid carcinoma. J Clin Endocrinol Metab. 2001 Feb;86(2):485-93.