The clinical staging of cancer – a process of classifying tumors – describes the extent of a cancer and helps physicians determine the proper treatment. The TNM system is used most often and is based on:
- T – size of the primary tumor
- N – regional lymph node involvement
- M – metastatic involvement or spread
Numbers after the T, N, and M give more details. Generally, the lower the number, the less advanced the cancer.
For example, a lung tumor staged as T1N0M0 would be confined to the lung with no regional node involvement and no evidence of spread. Such a tumor also would be referred to as stage I.
