appreciation of the level of development of a cancer, divided into three criteria summarized with the characters TNM
1. T refers to the originating tumor status
- T1 tumours are small tumors, usually not seen during physical or visual examination
- T2 tumours are identified tumors that remain inside the original organ (e.g. prostate)
- T3 tumours have broken through the covering or membrane of the original organ but have not yet spread into other organs
- T4 tumours have spread into other body organs
2. N refers to the level of invasion of lymph node cells by tumor cells
- NX – The lymph nodes cannot be checked
- N0 – There are no cancer cells in lymph nodes close to the primary tumor
- N1 – Cancer cells have been detected in lymph nodes
3. M provides the status of the metastases distribution
- M0 – No cancer has spread outside the primary tumor
- M1 – Cancer has spread outside the primary tumor
Oncologists use also subsclassifications of T2, T3 and M1.