Colorectal cancer / colon cancer / large bowel cancer staging systems

Normally used
o Dukes system
o TNM system
o AJCC stage groupings (not covered here)


TNM Classification of Malignant Tumours (TNM)

Common tumors have their own TNM classification.
Not all tumors have TNM classifications, e.g., brain tumors.

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

* T : size or direct extent of the primary tumor
o T0 - no evidence of tumor
o Tis- cancer in situ (tumor present, but no invasion)
o T1 - invasion through submucosa into lamina propria (basement membrane invaded)
o T2 - invasion into the muscularis propria (i.e. proper muscle of the bowel wall)
o T3 - invasion through the subserosa
o T4 - invasion of surrounding structures (e.g. bladder) or with tumour cells on the free external surface of the bowel

* N : degree of spread to regional lymph nodes
o N0: tumor cells absent from regional lymph nodes
o N1: tumor cells spread to closest or small number of regional lymph nodes
o N2: tumor cells spread to an extent between N1 and N3.
o N3: tumor cells spread to most distant or numerous regional lymph nodes

* M : presence of metastasis
o M0: no distant metastasis
o M1: metastasis to distant organs (beyond regional lymph nodes)

If a parameter is not accessed, an 'x' will be used.

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 vein
* C (1-4): a modifier of the certainty (quality) of the last mentioned parameter

further reading : http://en.wikipedia.org/wiki/TNM


Dukes classification
by British pathologist Dr Cuthbert Dukes

o Dukes A: Invasion into but not through the bowel wall

o Dukes B: Invasion through the bowel wall but not involving lymph nodes
* B1 : extend but note penetrating muscularis propria
* B2 : extend and penetrating muscularis propria

o Dukes C: Involvement of lymph nodes
* C2 : extend but note penetrating muscularis propria
* C2 : extend and penetrating muscularis propria

o Dukes D: Widespread metastases