| Ch 6 | Example of Cancer Classification | |
| Cancer Classification |
Colon cancer | |
Many classification systems are in use, although they are in fact very similar and concern the importance of invasion of the colic wall and proximal nodes. Generally, classification is done after surgery and the study of the surgical specimen.
With the following links, you will find diagrams of the main stages:
The following TNM Classification is the basis for stages which seem closer to the clinical reality.
T |
Description |
| TX | Primary tumour cannot be assessed |
| T0 | No evidence of primary tumour |
| Tis | Carcinoma in situ: intraepithelial or invasion of the lamina propria |
| T1 | Tumour invading submucosa |
| T2 | Tumour invading muscularis propria |
| T3 | Tumour invading through the muscularis propria into the subserosa, or into nonperitonealised pericolic or perirectal tissues |
| T4 | Tumour directly invading other organs or structures, and/or perforating visceral peritoneum |
| N | Description |
| NX | Regional nodes cannot be assessed |
| N0 | No regional lymph node metastasis |
| N1 | Metastasis in 1 to 3 regional lymph nodes |
| N2 | Metastasis in 4 or more regional lymph nodes |
The American Joint Committee for Cancer Classification has proposed the following grouping of TNM stages:
| Stages | Groups |
| Stage 0 | T0, Tis, N0, M0 |
| Stage 1A
Stage 1B |
T1, N0, M0 T2, N0, M0 |
Stage 2A Stage 2B |
T3, N0, M0 T4, N0, M0 |
|
Stage 3A Stage 3B Stage 3 C |
T1-T2, N1, M0 T3-T4, N1, M0 T1-T4, N2, M0 |
| Stage 4 | T1-T4, N1-N3, M1 |
In many studies (retrospective and long term studies), the Dukes classification is still in use (it was proposed before TNM stages by Dukes CE:Cancer of the rectum: ana analysis of 1,000 cases. J Pathol Bacteriol 50:527-539, 1940)
| Dukes | Description |
| A | T1-T2, N0, M0 |
| B | T3, N0, M0 |
| C1 | T1-T3,N1,M0 |
| C2 | T4,N0, M0 |
| D | T1-T4, N1-N3, M1 |
This is another post surgical classification (Astler VB, Coller FA: The prognostic significance of direct extension of carcinoma of the colon and rectum. Ann surg 139:846-852, 1954)
| Astler-Coller | Description |
| A | T1, N0, M0 |
| B | T2, N0, M0 |
| B2 | T3, N0,M0 |
| C1 | T1-T2, N1-N2, M0 |
| C2 | T3, N1-N2, M0 |
| D | T1-T4, N1-N3, M1 |
These results are generally observed and are issued from compilations
| Classification | Survival at 5 years |
| T1, N0, M0 |
> 95 % |
| T2,N0,M0 |
90 % |
| T3, N0, M0 |
> 75 % |
| T4, N0, M0 |
> 60 % |
| Duke’s A |
82 % |
| Duke’s B |
73 % |
| Classification | Risk of relapse |
| Colon (n = 479) |
28 % |
| Rectum (n = 430) |
30 % |
| Dukes A (n = 81) |
6 % |
| Dukes B (n = 558) |
31 % |
| Dukes C (n = 270) |
59 % |
according the study by Adloff JP, Chirurgie, 1989, 115, 228-236 .
For Dukes C stages, it has been confirmed that adjuvant chemotherapy improves the prognosis. For stage A cancers(82% of cases), only surgery is needed. For Stage B, trial results are still uncertain.
For French speaking readers the website of the Lorraine oncology network, Oncolor gives details on classifications and treatment of colon cancer
For English speaking readers, the NCI website is very valuable.
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