FTC is the second most common type of thyroid cancer. FTC is more common in areas of iodine deficiency. It is relatively uncommon in the US, representing < 15% of all thyroid cancer. It is more common in women than men. It usually presents as an asymptomatic mass. Unlike PTC it is less likely to be multifocal and it does not spread to local lymph-nodes as frequently as PTC. When it does spread it more commonly spreads through the blood stream, usually to the lungs or bone. Overall the prognosis is similar to PTC. Unlike PTC it is difficult to diagnose FTC on FNA. As we discussed earlier, FNA can only show that a nodule is a follicular neoplasm. Cancer can only be confirmed by removal of the thyroid lobe that contains the nodule and careful pathologic evaluation. Unfortunately, examination of the nodule by the pathologist at the time of surgery (frozen section) usually can’t settle the issue either. Typically, we have to wait several days for a final diagnosis. Therefore, with a diagnosis of follicular neoplasm we usually recommend a thyroid lobectomy for diagnosis, proceeding with a total thyroidectomy only if FTC is proven at the time of surgery.
As with PTC, total thyroidectomy is recommended for FTC for similar reasons. As malignancy is hard to prove at initial surgery, we may have to come back at a second procedure to remove the remaining lobe if cancer is found on final pathology. This is called a completion thyroidectomy. The risk of cancer in follicular tumors may increase with the size of the tumor. In tumors >4 cm, it may be reasonable to consider a total thyroidectomy as the initial surgical procedure. These decisions are made on a case by case bases. Because spread to local lymph nodes is uncommon, we don’t usually perform a level 6 node dissection as with PTC. A lymph node dissection may be needed if grossly malignant nodes are present at diagnosis. Following surgery, RAI may be recommended. After therapy patients are given suppressive doses of thyroid medication and followed in the same manner as PTC.