Recurrent parathyroid cancer is cancer that has recurred (come back) after it has been treated. 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.