Tumor lymph node metastases staging system

Staging [determination of the primary tumor size, extent of lymph node involvement, and the presence or absence of metastases, or sometimes referred to theTNM system (Table 85-2)]. Many tumors are staged according to the TNM system. Metastases are cancer cells that have spread to sites distant from the primary tumor site and have started to grow. The most frequently occurring sites of metastasis are the brain, bone, liver and lungs. 

The TNM system standardizes the classification of tumors. The T stands for the stage of tumor (the higher the number, the worse the prognosis), the N stands for the number of lymph nodes that are affected by the tumor (again, the higher the number, the worse the prognosis), and M stands for the presence of metastasis (0 for none, 1 for the presence of metastatic cells). 

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