Local recurrence of thyroid cancer generally means that the cancer has become clinically apparent in the immediate area were the thyroid gland was located. The actual space the thyroid occupies is known as the thyroid bed. For discussion purposes, the neck is divided into 7 zones. The diagram above demonstrates these. The thyroid bed is located in level 6. Typically when the thyroid is removed for papillary cancer we also remove the lymph nodes in this zone and in level 7 if needed. Recurrent disease here is usually lymph nodes with metastatic cancer. If the initial operation was accomplished based on sound oncological principles local recurrence is very uncommon.
Local recurrence may be found on examination, but most commonly it is suspected if the thyroglobulin level becomes elevated. Typically, an ultrasound of the thyroid bed and lateral neck is performed and if a suspicious area is found, an ultrasound guided needle biopsy is performed (FNA). if this is positive then a total body iodine scan or PET-CT scan is performed. Once the extent of recurrence is determined then a therapeutic approach can be organized.
At this point in our discussion, we will assume that recurrent disease is present in the thyroid bed only. Left untreated cancer could invaded local structures such as the recurrent nerve (threatening the voice) or the breathing tube (trachea) or swallowing tube (esophagus). RAI alone will not eradicate gross disease. Therefore we usually recommend surgery to remove the recurrence as well as remaining level 6 and 7 lymph nodes. RAI is commonly given after surgery to deal with any microscopic disease.