9. Staging of Thyroid Cancer

This chapter describes the significance of staging of thyroid cancers as it reflects the size and extent of tumor and ultimately its prognosis, especially in regard to mortality. Thus, staging differs from risk of recurrence which is specifically linked to the American Thyroid Association risk stratification classification system of so-called “low risk”, “intermediate risk”, and “high risk”. Staging provides physician with insights into potential outcome and may govern the intensity of both follow-up and therapy.The chapter describes the various different staging systems that have been developed and their respective utility, and how staging differs for medullary thyroid carcinoma and anaplastic carcinoma.In general, the “stage” of a cancer refers to a phase in the course of the tumor when it has reached some defined level of extent. The extent of the tumor is a measure of its size and whether it has spread elsewhere. As thyroid cancers grow, they are first confined to the thyroid gland and then may extend in variable degrees to the subcutaneous tissues and lymph nodes of the neck and finally, potentially to distant sites of the body. Staging a tumor allows a more accurate description of the extent of disease in a given patient in objective and standardized terms. Staging permits communication between patients and physicians about their prognosis.