The TNM staging system is useful but has not been uniformly accepted because it is more complex than other staging systems. Many clinicians use the DeGroot system, which classifies tumors into Class 1 (confined to the thyroid), Class 2 (involving regional nodes), Class 3 (locally invasive) and Class 4 (distant metastases). Others use the AGES (age, grade, extent and size) or AMES (age, metastases, extent and size) classifications to predict the tumor's aggressiveness. Staging systems have been designated for papillary and follicular carcinoma . There are no generally accepted staging systems for medullary carcinoma or anaplastic carcinoma.
