ABSTRACT
The American Joint Committee on Cancer (AJCC) classification system (TNM staging) is based on the fact that cancers of an anatomic site act in similar ways. In general, as the primary tumor (T) grows it begins to invade locally and eventually spreads to regional lymph nodes that drain the area of the tumor (N). In addition to nodal disease the tumor may spread either by lymph drainage or by hematogenous spread and involve distant sites of the body or nonregional lymph nodes (i.e., metastasis, M). Evaluation by clinical means allows for the assignment of a clinical stage. In some instances, evaluation of the primary tumor and nodal disease may or may not be assessed accurately by clinical means and, if surgical intervention is pursued, a pathologic stage is assigned based on findings at the time of operation as well as histologic analysis of the primary tumor and regional lymph nodes.1 This classification system is known as the TNM staging system and is identical to that of the International Union Against Cancer (IUCC).
