Management of regional nodes in thyroid cancer

Thyroid cancer metastasizes to regional lymph nodes early and often. The impact of these metastases on outcome depends on the histological subtype and the size, number and location of those metastases, as well as patient's age. Whilst clinically apparent lateral nodal metastases have a significant impact on both survival and recurrence, microscopic metastases to the central as well as lateral neck in well differentiated thyroid cancer (WDTC) do not affect outcome. In this review article we discuss the lymphatic drainage of the thyroid gland, and assessment of regional lymph nodes. We go onto describe the impact that nodal metastases have on outcome, before discussing the role of therapeutic and prophylactic neck dissection. Whilst all authors support the use of therapeutic neck dissection, there is considerable controversy over prophylactic central neck dissection. Despite a significant rate of occult disease in the central compartment of clinically negative necks, removal of this tissue results in morbidity without improving outcome. The role of the neck node metastases in decision making in relation to adjuvant radioactive iodine is discussed as is the process of post operative surveillance, and the role of observation in small volume persistent nodal disease. The focus of this article is WDTC, however the principles of management of the neck in medullary and anaplastic carcinoma are also discussed.