tumornodemetastasis

Tumornodemetastasis, commonly referred to as the TNM cancer staging system, describes the extent of solid tumors. The T component describes the size and direct extent of the primary tumor: for most cancers T ranges from T0 to T4, with higher numbers reflecting greater invasion or size. The N component describes regional lymph node involvement, from N0 (no regional nodes affected) to higher N categories (N1-3 in many systems), indicating increasing nodal spread. The M component describes distant metastasis, with M0 indicating no distant spread and M1 indicating distant metastasis; some cancer types also include subcategories such as M1a, M1b. The TX, NX, MX codes may be used when the primary tumor, nodes, or metastasis cannot be assessed.

TNM categories are combined to yield an overall stage group, usually from 0 to IV, which provides prognostic information and guides treatment decisions. Staging is cancer-specific; the exact definitions of T, N, and M and the resulting stage group differ among tumor types. Clinically, staging can be assessed before treatment (cTNM) using imaging and biopsy, or after surgery and pathology (pTNM). The system is maintained by organizations such as the American Joint Committee on Cancer (AJCC) and the Union for International Cancer Control (UICC) and is periodically updated to reflect new evidence.

Limitations include variation by cancer type and the growing role of molecular and histopathological factors that complement TNM staging, rather than replace it. Despite limitations, TNM remains a standard framework for describing cancer extent and planning management.