T - Tumour Stage
Tis: carcinoma in situ
T1: tumour 2cm or less and 5mm or less depth of invasion
T2: tumour 2cm or less and with 5-10mm depth of invasion OR 2-4cm in width with <10mm depth of invasion
T3: tumour more than 4cm width OR more than 10mm depth of invasion
T4a: tumour invades through the cortical bone of the mandible or maxillary sinus, or invades skin of the face
T4b: tumour invades masticator space, pterygoid plates, or skull base, or encases internal carotid artery
N – Lymph Node status
N0: no regional lymph node involvement
N1: metastasis in a single ipsilateral node; 3cm maximum diameter with no extranodal extension
N2a: as per N1 but with extranodal extension, or 3-6cm maximum diameter without nodal extension
pN2b: metastasis in multiple ipsilateral nodes, none more than 6cm, without extranodal extension
pN2c: metastasis in bilateral or contralateral nodes, none more than 6cm without extranodal extension
N3a: metastasis in a lymph node more than 6cm without extranodal extension
N3b: metastasis in a lymph node mode than 3cm diameter with extranodal extension or multiple ipsilateral, contralateral or bilateral nodes with extranodal extension