Primary tumor (T)

• TX: Primary tumor cannot be assessed
• T0: No evidence of primary tumor
• T1: Tumor 2 cm or less in greatest dimension without extraparenchymal extension*
• T2: Tumor more than 2 cm but 4 cm or less in greatest dimension without extraparenchymal extension*
• T3: Tumor more than 4 cm and/or tumor having extraparenchymal extension*
• T4a: Tumor invades skin, mandible, ear canal, and/or facial nerve
• T4b: Tumor invades skull base and/or pterygoid plates and/or encases carotid artery

* [Note: Extraparenchymal extension is clinical or macroscopic evidence of invasion of soft tissues. Microscopic evidence alone does not constitute extraparenchymal extension for classification purposes.]

Regional lymph nodes (N)

• 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
• N2: Metastasis in a single ipsilateral lymph node, more than 3 cm but 6 cm or less in greatest dimension; or in multiple ipsilateral lymph nodes, 6 cm or less in greatest dimension; or in bilateral or contralateral lymph nodes, 6 cm or less in greatest dimension
  • N2a: Metastasis in a single ipsilateral lymph node, more than 3 cm but 6 cm or less in greatest dimension
  • N2b: Metastasis in multiple ipsilateral lymph nodes, 6 cm or less in greatest dimension
  • N2c: Metastasis in bilateral or contralateral lymph nodes, 6 cm or less in greatest dimension
• N3: Metastasis in a lymph node more than 6 cm in greatest dimension

Distant metastasis (M)

• MX: Distant metastasis cannot be assessed
• M0: No distant metastasis
• M1: Distant metastasis

Stage I

• T1, N0, M0

Stage II

• T2, N0, M0

Stage III

• T3, N0, M0
• T1, N1, M0
• T2, N1, M0
• T3, N1, M0

Stage IVA

• T4a, N0, M0
• T4a, N1, M0
• T1, N2, M0
• T2, N2, M0
• T3, N2, M0
• T4a, N2, M0

Stage IVB

• T4b, any N, M0
• Any T, N3, M0

Stage IVC

• Any T, any N, M1