TNM Classification of Malignant Tumors

The TNM system for the classification of malignant tumors is a form of clinical shorthand used to describe the extent (staging) of a cancer. These components are given a number that reflects the absence or presence and extent of the disease. For example, a tumor of the colon that is classified as T2N1M0 would have extended into the colonís muscular wall, spread to 1 to 3 regional lymph nodes but without evidence of distant metastasis.

T-the primary tumor
TX primary tumor cannot be assessed
T0 no evidence of primary tumor
Tis carcinoma in situ
T1 tumor invades submucosa
T2 tumor invades muscularis propria
T3 tumor invades through muscularis propria into subserosa or into
non-peritonealized pericolic or perirectal tissues.
T4 tumor directly invades other organs or structures and/or
perforates visceral peritoneum

N-regional lymph nodes
NX regional lymph nodes cannot be assessed
N0 no regional lymph node metastasis
N1 metastasis in 1 to 3 regional lymph nodes
N2 metastasis in 4 or more regional lymph nodes

M-distant metastases
MX distant metastasis cannot be assessed
M0 no distant metastasis
M1 distant metastasis