Table 2.

Regional lymph node staging

Nx	Regional lymph nodes cannot be assessed
N0	No regional lymph node metastasis
N1	Metastasis in a single ipsilateral lymph node, 3 cm or less in greatest dimension
N2a	Metastasis in a single ipsilateral lymph node, more than 3 cm but less than 6 cm in greatest dimension
N2b	Metastasis in a multiple ipsilateral lymph nodes, none more than 6 cm in greatest dimension
N2c	Metastasis in bilateral or contralateral lymph nodes, none more than 6 cm in greatest dimension
N3	Metastasis in a lymph node more than 6 cm in greatest dimension (Midline nodes are considered ipsilateral nodes)

(Adapted from UICC / AJCC TNM Classification of Malignant Tumors, 6^th edition, 2002)