The TNM staging system is used in the evaluation of many cancers. Each individual cancer has its own slight variation on the system, however, it is universally applicable in its basic format.
T: size or direct extent of the primary tumour
- Tx: tumor cannot be evaluated
- Tis: carcinoma in situ
- T0: no signs of tumour
- T1, T2, T3, T4: size and/or extension of the primary tumour
- Depending on the cancer, T1-2 typically involve spread within an organ, T3 – spread to the surface of the organ and related structures and T4 involves spread to other adjacent structures or organs.
N: degree of spread to regional lymph nodes
- Nx: lymph nodes cannot be evaluated
- N0: tumor cells absent from regional lymph nodes
- N1: regional lymph node metastasis present; (at some sites: tumor spread to closest or small number of regional lymph nodes)
- N2: tumour spread to an extent between N1 and N3 (N2 is not used at all sites)
- N3: tumour spread to more distant or numerous regional lymph nodes (N3 is not used at all sites)
M: presence of metastasis
- Mx: distant metastasis cannot be evaluated
- M0: no distant metastasis
- M1: metastasis to distant organs (beyond regional lymph nodes)