Staging

The TNM System

A clinical staging system called the TNM system* allows the clinician to design treatment strategies, compare results, and assess the likelihood of treatment success or determine the prognosis. Each letter in TNM has a specific meaning:

• T = the size of the primary Tumor
• N = the status of the cervical lymph Nodes
• M = the presence or absence cancer in sites other than the primary tumor (Metastasis)

Staging is defined through physical examination, diagnostic tests, and biopsies.

What Does Each Stage Mean?

I. Codes Describing the Tumor (T)

• TX primary tumor cannot be assessed
• T0 no evidence of primary tumor
• Tis carcinoma in situ
• T1 tumor less than 2 centimeters (cm) in greatest dimension
• T2 tumor more than 2 cm but not more than 4 cm in greatest dimension
• T3 tumor more than 4 cm in greatest dimension
• T4 tumor invades adjacent structures (mandible, tongue musculature, maxillary sinus, skin)

II.Codes Describing Nodal Involvement (N)

• NX regional lymph nodes cannot be assessed
• N0 no regional lymph node metastasis
• N1 metastasis in a single ipsilateral lymph node, less than 3 cm in greatest dimension
• N2a metastasis in a single ipsilateral lymph node, more than 3 cm but not more than 6 cm in greatest dimension
• N2b metastasis in 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

III. Codes Describing Metastasis (M)

• M0 no distant metastasis
• M1 distant metastasis

IV. Stage Grouping

• Stage I T1N0M0
• Stage II T2N0M0
• Stage III T3N0M0
  • T1 or T2 or T3N1M0
• Stage IV T4N0 or N1M0
  • Any T, N2, or N3M0
  • Any T, any N, M1

*Modified from American Joint Committee for Cancer Staging and End-Results Reporting. Chicago, American Joint Committee on Cancer, 1988.