60% of high-priority research goes unfunded.
Surgery for parathyroid cancer
Surgery is the primary treatment for parathyroid cancer. Surgery is used to:
- potentially cure the cancer by completely removing the parathyroid gland and surrounding tissue
- remove recurrent disease
- remove metastases
It is important to manage hypercalcemia (increased blood calcium level) before surgery. Hypercalcemia is treated with intravenous fluids together with medications to increase calcium and water loss from the kidneys.
Before or during surgery, it is often difficult to tell how many of the 4 parathyroid glands are affected. Parathyroid tumours can be benign (non-cancerous) hyperplastic nodules or adenomas. Much more rarely, they can be malignant lesions known as parathyroid carcinomas. The type of surgery done depends mainly whether the doctor believes there is more than one tumour. It will also depend on whether the doctor suspects the tumour is benign or malignant based on:
- extremely high calcium and parathyroid hormone blood levels
- the appearance and consistency of the tumour
- if the tumour is attached to nearby structures
Side effects of surgery depend on the type of surgical procedure.
En bloc resection
En bloc resection is the preferred treatment for parathyroid cancer. Recognizing that the tumour is cancerous before or during surgery allows the surgeon to choose an en bloc resection. This surgery reduces the risk of local recurrence better than a parathyroidectomy (removal of only the parathyroid gland).
- Parathyroid cancer often invades the thyroid on the same side as the tumour.
- An en bloc resection removes the tumour along with part of the thyroid, nearby neck muscles, tissues around the trachea and the recurrent laryngeal nerve.
- The recurrent laryngeal nerve is removed only if there is evidence that the cancer has spread to the nerve. This includes a paralyzed vocal cord or the surgeon may see evidence of invasion during surgery.
- Care is taken not to rupture the tumour capsule during surgery because of the high risk of spreading (seeding) tumour cells into the neck.
- If tumour cells spread, it would prevent successful treatment and increase the risk of recurrence.
Surgical re-excision is the first choice for treatment of a local neck recurrence because it can provide long-term control of the disease.
- Most of the time, a recurrence is multifocal, which means it occurs in many sites in the neck. These sites include the recurrent laryngeal nerve, trachea, esophagus and the blood vessels of the neck and mediastinum (the area behind the centre of the chest). The surgeon will remove as much of the cancer as possible while trying to spare the recurrent laryngeal nerve and avoid vocal cord paralysis.
- Sometimes, the recurrent laryngeal nerve is removed when there is a single recurrent tumour. In this case, the benefits of controlling the cancer outweigh the side effects of removing the nerve (which may include vocal cord paralysis).
- Sometimes repeat excisions are necessary to control hypercalcemia caused by tumour growth.
Lymphadenectomy (removal of lymph nodes) is only done if the lymph nodes in the neck are enlarged or firm, which suggests the presence of disease. Lymphadenectomy is not a standard part of surgery because parathyroid cancer is slow growing and has low rate of spread to the lymph nodes. Removal of lymph nodes in the neck is called a cervical lymphadenectomy or cervical lymph node dissection.
Removal of metastases
Parathyroid cancer is a slow-growing cancer, so surgery to remove local metastases from the neck or lymph nodes, or distant metastases from the lungs, bone or liver, can provide good control of the disease. Whenever possible, surgery to remove metastatic tumours or as much of the tumour as possible is done to control hypercalcemia caused by the tumours.