Medullary cancers tend to spread to large numbers of lymph nodes very early on, and therefore it requires a much more aggressive operation than does the more localized cancers such as papillary and follicular. This cancer requires complete thyroid removal and a dissection to remove the lymph nodes of the front and sides of the neck. If this cancer is found after it has already spread, it cannot be cured in most cases. The cancer can hide, and often an operation cannot remove all the tumors. This cancer has to be carefully watched, and frequent blood test need to be done.
Medullary tumors are the third most common of all thyroid cancers.
These C cells make a different hormone called Calcitonin, which has nothing to do with the control of metabolism the way thyroid hormone does. The production of this hormone can be measured after an operation to determine if the cancer is still present, and if it is growing. My thyroid was completely removed in 1981. A blood test for Calcitonon is an indicator of medullary thyroid cancer. At that time, normal Calcitonin scale was considered to be 40 or below, and my level was greater than 4000.