Tumor extension beyond limits of organ of origin. Formal (scientific) definition: "That area extending from the periphery of an involved organ that lends itself to removal en bloc with a portion of—or an entire—organ with outer limits to include at least the first level nodal basin."
Delineation of the outer limit between regional and distant spread is not always clear (can be defined differently by different physicians). En bloc resection not always feasible or may have been shown not to be necessary. (Example: decline in the use of radical mastectomy to treat breast cancer)
Regionalized tumors are most difficult to categorize properly.
- Regional by direct extension;
- Regional to lymph nodes;
- Regional both by direct extension and lymph nodes;and
- Regional, not otherwise specified.
Methods of Spread:
- Invasion through entire wall of organ into surrounding organs and/or adjacent tissues ("direct extension" or "contiguous spread").
- Tumor invasion of walls of lymphatics where cells can travel through lymphatic vessels to regional lymph nodes where they are "filtered" out and begin to grow in the nodes.
- Combination of direct extension and lymph node involvement.
Cancer becomes regionalized when there is the potential for spread by more than one lymphatic or vascular supply route. Examples:
- Tumor in hepatic flexure of colon with extension along lumen to ascending colon—stage as localized because both areas drain to the same lymph nodes.
- Sigmoid tumor extending into rectum—stage as regional because tumor now has potential for tumor cell drainage to both the iliac and mesenteric nodes.
Guidelines for Staging Regionalized Disease:
Principle of bracketing or exclusion:
- Rule out "confined to organ"—establish that tumor is more than localized.
- Rule out distant spread by reading operative report for comments about seeding, implants, live nodules, etc., and read diagnostic reports for references to distant disease.
- If local and distant categories have been ruled out, case is regionalized.
Terminology to watch carefully:
- "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 lung with peribronchial lymph node metastases." Metastases in this sense means involvement by the tumor. Such a case would still be regionalized. Learn the names of regional nodes for each primary site.