Parathyroid cancer can recur (come back) after it has been treated.

The cancer may come back in the tissues or lymph nodes of the neck or in other parts of the body. More than half of patients have a recurrence. The parathyroid cancer usually recurs between 2 and 5 years after the first surgery, but can recur up to 20 years later. It usually comes back in the tissues or lymph nodes of the neck. High blood calcium levels that appear after treatment may be the first sign of recurrence.