TNM

TNM Classification of Malignant Tumours (TNM) is the cancer staging system developed and maintained by the International Union Against Cancer (UICC) to maintain consensus on one globally recognised standard for categorising cancer. The TNM classification is also used by the American Joint Committee on Cancer (AJCC) and the International Federation of Gynecology and Obstetrics (FIGO). In 1987, the UICC and AJCC staging systems were unified into a single staging system.

Broad outline

Each tumor has its own TNM classification. Not all tumors have TNM classifications, but most do. For instance, there is no TNM classification for brain tumors.

The general outline for the TNM classification is below. The values given in parenthesis give a range of what can be used for all cancer types, but not all cancers use this full range.

Mandatory parameters ('T', 'N', and 'M')

T (a,is,(0),1-4): size of the tumour Relates to Tumour size and local spread.
N (0-3): spreading into lymphatic nodes
M (0/1): spreading into other organs (metastasis)

Other parameters

G (1-4): the grade of the cancer cells (i.e. they are "low grade" if they appear similar to normal cells, and "high grade" if they appear poorly differentiated)
R (0/1/2): the completeness of the operation (resection-boundaries free of cancer cells or not)
L (0/1): invasion into lymphatic vessels
V (0/1): invasion into veins
C (1-4): a modifier of the certainty (quality) of the last mentioned parameter

Prefix modifiers

c: stage given by clinical examination of a patient. The c-prefix is implicit in absence of the p-prefix
p: stage given by pathologic examination of a surgical specimen
y: stage assessed after neoadjuvant therapy

For the T, N and M parameters exist subclassifications for some cancer-types (e.g. T1a, Tis, N1i).

Examples

Small, low grade cancer, no metastasis, no spreading to lymph nodes, cancer completely removed, resection material seen by pathologist - pT1 pN0 M0 R0 G1
Big, high grade cancer, with spread to lymph nodes and other organs, not completely removed, seen by pathologist - pT4 pN2 M1 R1 G3