Back to leedsth.nhs.ukColorectal Surgery Website
Classification of Colorectal cancer
There are two ways in which colorectal cancer can be classified. The first method is the Duke's system, this has 4 classifications which are Duke's A, B, C or D depending on how far the cancer has developed and spread.
| Duke's Classification | |
|---|---|
A |
Tumour confined within the muscle layer |
B |
The tumour has spread through the muscle layer but does not involve any lymph nodes |
C |
Any tumour involving the lymph nodes |
D |
Any tumour with distant metastases |
The other method of classification is the TNM system which is much more precise than the Duke's system. In this system T stands for the primary Tumour, N stands for regional lymph Nodes which the cancer has spread to, M stands for distant Metastases which is where the cancer has spread to another part of the body. Also added to this has been R which stands for Resection, whether the whole tumour has been removed or not.
| TNM Classification System | ||
|---|---|---|
| Tumour | Tis | Tumour in situ, the tumour is still contained within the innermost layer of the bowel wall |
| T1 | The tumour is spread into the submucosa (the second layer of the bowel wall) | |
| T2 | The tumour extends into the muscle of the bowel wall | |
| T3 | The tumour involves all layers of the bowel wall by there is no involvment of local organs | |
| T4 | The tumour has extended through the wall of the bowel and involves nearby organs | |
| Lymph Nodes | N0 | No lymph node involvement found |
| N1 | Cancer cells found in 1-3 nearby lymph nodes | |
| N2 | Cancer found in 4 or more lymph nodes | |
| Metastases | M0 | No distant spread of the cancer found |
| M1 | Distant spread of the cancer found | |
| Resection | R0 | Primary tumour completely removed |
| R1 | Primary tumour not completely removed | |
For more information on the classification systems please look at the following websites
American Cancer Society - a page on the different classifications of colorectal cancer.
Cancer Research UK - more information on TNM staging.