Regional (codes = 2-5)
Regional stage is perhaps the broadest category as well as the most difficult to properly identify. A brief definition of regional stage is tumor extension beyond the limits of the organ of origin without being distant.
Although the boundary between localized and regional tumor extension is usually well-identified, the boundary between regional and distant spread is not always clear and can be defined differently by physicians in various specialities.
Cancer becomes regional when there is the potential for spread by more than one lymphatic or vascular supply route. For example, a tumor in the hepatic flexure of the colon with extension along the lumen to the ascending colon is staged as localized because both areas drain to the same lymph nodes. On the other hand, a sigmoid colon tumor extending into the rectum is staged as regional because the tumor now has potential for the tumor cells to drain to both the iliac and the mesenteric nodes.
Regional stage has several varieties, each of which is described in detail below.
- 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)
These codes and subcategories describe different methods of regional spread of tumor:
- Invasion through entire wall of organ into surrounding organs and/or adjacent tissues (code 2, regional by direct extension or contiguous spread);
- Tumor invasion of walls of lymphatics where cells can travel through lymphatic vessels to nearby lymph nodes where they are "filtered" out and begin to grow in the nodes (code 3, regional to lymph nodes); and
- A combination of direct extension and lymph node involvement (code 4, regional by direct extension and to regional nodes).
A fourth category of regional stage is code 5, regional not otherwise specified. This category may be used when it is unclear whether the tissues are involved by direct extension or lymph nodes, or when the other categories are not applicable, such as for staging non-Hodgkin and Hodgkin lymphoma of more than one lymph node chain.
Clinicians may consider some terms differently than cancer registrars consider them. Therefore, it is important to understand the words used to describe the spread of the cancer and how they are used in staging. For example:
- "Local" as in "carcinoma of the stomach with involvement of the local lymph nodes." Local nodes are the first group of nodes to drain the primary. Unless evidence of distant spread is present, such a case should be staged as regional lymph nodes, not localized.
- "Metastases" as in "carcinoma of the lung with peribronchial lymph node metastases." Metastases in this sense means that the regional (peribronchial) lymph nodes are involved by tumor. Such a case would still be staged as regional lymph nodes. Learn the names of regional nodes for each primary site (see the Summary Staging Manual for details).