Recurrent differentiated thyroid cancer.

OBJECTIVE: To discuss the risk of recurrence in patients with differentiated thyroid cancer and emphasize the importance of risk-group stratification.
METHODS: Common risk factors associated with recurrent thyroid cancer are outlined, and appropriate management strategies are reviewed.
RESULTS: The overall prognosis in patients with differentiated thyroid cancer is excellent. Factors associated with recurrent thyroid cancer include extrathyroidal extension of the primary tumor, bulky nodal metastatic lesions, macroscopic local invasion, and aggressive histologic subtypes. The locoregional recurrence and mortality are higher in patients with high-risk thyroid cancers. Patients initially presenting with locally aggressive and advanced thyroid cancer have a higher incidence of recurrent disease in the thyroid bed or nodal metastasis. These patients also have a high incidence of distant metastatic lesions. Locally recurrent thyroid cancer may be seen in more than 25% of patients with aggressive differentiated thyroid cancer. Recurrent disease in the thyroid bed can be a difficult problem to manage because of the proximity of the tumor to the recurrent laryngeal nerve, visceral structures in the central compartment, and occasional involvement of the trachea or larynx. External beam radiation therapy after surgical treatment may be important for better local control in the thyroid bed region, especially in patients with poorly differentiated histologic features. The role of additional radioiodine therapy remains undefined at this stage.
CONCLUSION: Management of patients with recurrent thyroid cancer necessitates a true multidisciplinary approach. These patients require close follow-up, with cross-sectional imaging and positron emission tomographic scanning in selected individuals.