Describe TNM classification of thyroid cancer.

T (Tx (cannot assess) T0 (no tumor), T1 (tumor 2cm or less limited to thyroid), T1a (tumor <1cm), T1b (tumor between 1 and 2 cm), T2 (Tumor between 2-4 cm limited to thyrodi), T3a (Tumor >4cm limited ) T3b (any size but w/extrathyroid strap muscle invasion), T4a (beyond capsule invades larynx/trachea...) T4b (invades fascia prevertebral/carotid/mediastinal vessels)) N (X indetermined, 0 no nodes, 1 regional nodes, 1a level VI, 1b other compartments uni or bilateral) M (0 or 1)