Collaborative Stage

Note: Site-Specific Factors 3-6 are used to code the presence or absence of lymph node involvement in each of 7 different levels and other groups defined by AJCC. The definitions of the levels are the same for all applicable head and neck sites. One digit is used to represent lymph nodes of a single level, with the three digits of Site-Specific Factor 3 representing lymph nodes of, respectively, Levels I-III; the digits of Site-Specific Factor 4 representing lymph nodes of Levels IV and V and the retropharyngeal nodes; the digits of Site-Specific Factor 5 representing lymph nodes of Levels VI and VII and the facial nodes; and the digits of Site-Specific Factor 6 representing the remaining Other groups as defined by AJCC. In each digit, a code 1 means Yes, the nodes are involved.

Code	Description
000	No lymph node involvement in Levels IV or V or retropharyngeal
100	Level IV lymph node(s) involved
010	Level V lymph node(s) involved
001	Retropharyngeal nodes involved
110	Level IV and V lymph nodes involved
101	Level IV and retropharyngeal nodes involved
011	Level V and retropharyngeal nodes involved
111	Level IV and V and retropharyngeal lymph nodes involved
999	Unknown if regional lymph node(s) involved, not stated Regional lymph nodes cannot be assessed Not documented in patient record

CS Site-Specific Factor 4
Levels IV-V and Retropharyngeal Lymph Nodes for Head and Neck