| Ch 6 | Example of Cancer Classification | |
| Cancer Classification |
Prostate Cancer | |
The following drawings are available as diagrams illustrating the various stages:
| Classification | Description |
| TX | Primary tumour cannot be assessed |
| T0 | No evidence of primary tumour |
| T1 T1a T1b T1c |
Clinically imperceptible tumour neither
palpable nor visible by imaging: |
| T2 T2a T2b T2c |
Tumour confined to prostate Tumour involving 50% of 1 lobe or less Tumour involving >50% of only one lobe Tumour involving both lobes |
| T3 T3a T3b |
Tumour extending through the prostate capsule Extracapsular extension (unilateral or bilateral) Tumour invading seminal vesicle(s) |
| T4 T4 |
Tumour is fixed or invades adjacent structures Tumour is fixed or invades adjacent structures other than seminal vesicles: bladder neck, external sphincter, rectum, levator muscles, and/or pelvic wall |
| Classification | Description |
| NX | Regional lymph nodes were not assessed |
| N0 | No regional lymph node metastases |
| N1 | Metastases in regional lymph node(s) |
As well as this TNM classification, we also study the Gleason classification which describes histological grading.
Here are some examples of the Gleason classification:
In fact, as many tumours, prostate cancer is very heterogeneous in its differentiation grade, from a very well differentiated grade to a totally undifferentiated grade. The latter grades are the most dangerous since they rapidly become hormone-independent and quickly give birth to remote metastases. Gleason adds two of the tumour's components (from 1 to 5):
- The most represented component of the tumour
- The most indefferentiated component of the tumour (which can be the same as the previous one).
So we speak of a Gleason tumour Grade (3 + 1) or (4 + 3), and so on..
The TNM classification has a major role in the survival of patients with prostate cancer:
| Survival | |||
| at 5 years | at 10 years | at 15 years | |
| T1 | 85% |
65% |
40% |
| T2 | 83% |
55% |
35% |
| T3 | 68% |
38% |
20% |
| T4 | < 20% |
< 5% |
- |
These figures are very interesting when correlating to the age of patients:
Therefore treatment should be adapted to the stage and the age of the patient. Older patients with a limited T1 could benefit from watchful waiting and only be treated when major clinical symptoms appear, whereas young patients (65 and under) with more advanced disease should be actively treated since cancer will probably severely shorten their lifespan.
Among other important prognostic factors, are:
Partin elaborated tables in order to determine if cancer goes beyond prostate limits according to T, PSA level and Gleason grading. The higher the PSA level, the more elevated the Gleason grade, and the greater the risk of the tumour going beyond prostate limits and quickly giving birth to node or remote metastases.
The graph below shows the 5 year survival according to Gleason Grade and T stage.
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|
In this older graph, T2c stage is in reality
the currently used T2b stage, the T2b is a bilateral T2a, and T2a is a
unilateral T2a. |
The knowledge of the risk of capsule invasion is very important for the indication of therapy. A prostate tumour extending beyond the capsule should not be operated (the limits of exeresis will never be free of disease) but can possibly be treated by radiotherapy. As from this stage (and higher), the risk of node and remote metastases is very high and trials have shown that the adjuvant use of hormone therapy (surgical or chemical castration, anti-androgens) increases patient survival.
For French speaking readers, the website of the AFU: Association Française d'Urologie is very interesting.For those readers, another interesting site is the Lorraine oncology network website, Oncolor which describes classifications as well as decision trees.
For English speaking readers, the NCI website is of great interest as well the American Urological Association website.
For macroscopic and microscopic study of the surgical specimen, the website, Webpath, from University of Florida is very interesting.
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