TNM

TNM refers to a cancer staging system used to describe the extent of a cancer within the body. It stands for Tumor, Node, Metastasis. The T category describes the size and local extent of the primary tumor, with designations such as Tis (carcinoma in situ), T1–T4 (increasing size or local invasion), or TX/T0 when the primary may not be assessable. The N category assesses regional lymph node involvement, with N0 indicating no regional nodes involved and N1–N3 indicating increasing nodal spread. The M category indicates distant metastasis, with M0 meaning no distant metastasis and M1 indicating distant metastatic spread. The T, N, and M values are combined to assign an overall stage, typically denoted as 0, I, II, III, or IV, though stage groupings vary by cancer type. Clinico-pathological variants exist, such as cTNM (clinical staging based on imaging and examination) and pTNM (pathological staging based on surgical specimen), and post-neoadjuvant stages may use ypTNM. The TNM system is used for prognosis, treatment planning, and reporting in clinical trials; it provides a standardized language across institutions and countries. Its definitions are updated periodically by major authorities, notably the American Joint Committee on Cancer (AJCC) and the Union for International Cancer Control (UICC), leading to annual or edition-based revisions that reflect advances in tumor biology and diagnostics. Example: breast cancer staged as T2N0M0.