In the process of staging, a corresponding numerical number is assigned to each group defined by the Summary Staging System. The table directly below shows the code structure of summary staging. Note that "regional" stage comprises four distinct stages, dependent upon disease spread.
|2||Regional by direct extension only|
|3||Regional lymph nodes involved only|
|4||Regional by BOTH direct extension AND lymph node involvement|
|5||Regional, NOS (Not Otherwise Specified)|
|7||Distant site(s)/node(s) involved|
|9||Unknown if extension or metastasis (unstaged, unknown, or unspecified) Death certificate only case|