To determine risk factors for presence of lymph node or distant metastases in patients with follicular thyroid cancer (FTC) at the time of diagnosis and whether there is a relationship between the type of tumor invasion and metastases. FTC often presents distant metastases at the initial diagnosis. As distant metastases are independent prognostic factors in a patient's survival, determination of clinicopathologic characteristics for patients who are at higher risk for developing metastases is of greater clinical importance. The prognostic significance of gender (male vs. female), age (40 mm), number of lesions (uni- vs. multifocality), type of invasion (minimally invasive vs. widely invasive), and oncocytic changes (with vs. without) were analyzed in 207 patients, according to presence of lymph node and distant metastases at the time of initial surgery. According to the type of invasion, the carcinoma-specific survival and the disease-free survival of minimally invasive (MI) and widely invasive (WI) FTC were estimated and compared. None of the 127 patients with MI growth presented with lymph node metastases but 9.4% distant metastases. Overall risk factors for the presence of lymph node metastases at the initial diagnosis were multifocality (P = 0.02) and widely invasion (P = 0.0001) and for distant metastases age >45 years (P = 0.007), tumor size larger than 40 mm (P = 0.03) and widely invasion (P = 0.0001).WI-FTC patients show larger tumors (P = 0.0001), older age (P = 0.0001), and are presented more frequently in recurrent goiter disease (P = 0.0001). The estimated 10 years carcinoma-specific survival and disease-free survival for MI-tumors were significantly better than for WI-tumors (P = 0.0001). Total thyroidectomy is recommended in all patients with FTC because of early distant metastases. Patients with WI-FTC need a more aggressive surgical treatment because of higher tendency for lymph node metastases. MI-FTC has an excellent prognosis with no sign of lymph node metastases, which emphasizes a limited need for nodal surgery.

At the time of diagnosis, one-third of medullary thyroid carcinoma (MTC) patients show lymph node (LN) or distant metastasis. A metastasized MTC requires d