Staging & Grading

Staging

‘Staging’ refers to finding out how far the cancer has spread.
This is investigated in a number of different ways. Initially, at the digital rectal examination, the surgeon notes whether he or she can feel the tumour as a nodule or irregularity on the prostate, and if so, whether it extends beyond the prostate itself. This is referred to as clinical staging. However, the exact stage is not easy to determine from a clinical examination. Sometimes the number of biopsy cores with cancer in them is reported by the pathologist, and gives an indication of the extent of the cancer. If surgery is completed and the prostate removed, staging can be determined more precisely by pathological (using a microscope) examination of the prostate tissue and surrounding organs which have been removed. This is called pathological staging.

TNM system
This is a system for recording how far the cancer has spread. ‘T’ refers to tumour, ‘N’ to node and ‘M’ to metastasis. The system
is used around the world to stage cancers which develop as tumours and metastasise. In the TNM system for prostate
cancer, the staging is as follows:
T1   Tumour so small that it cannot be detected by feeling the prostate or on ultrasound.
T2 Tumour which can be felt, but is still confined within prostate.
T3   Tumour extends through the prostatic capsule and may have spread into seminal vesicles.
T4   Tumour invades adjacent structures other than seminal vesicles, such as bladder, rectum, pelvic wall.
N1   Tumour is found in lymph nodes.
M1 Tumour has distant metastases. This is a simplified description. Within each stage are subgroupings a–d, which indicate the extent of spread within that group.
tnm-staging
The Gleason Grading System
Grading systems score how abnormal the tissue looks. This is also related to how fast the cancer is likely to grow. Sometimes a pathology report refers to tissue as ‘poorly differentiated’. This is another way of saying that the tissue does not look like the normal tissue (fully differentiated). The main system for grading tissue taken at biopsy is the Gleason grading system. The pathologist identifies the two most common tissue patterns and gives them a score from 1 (most normal or differentiated) to 5 (most abnormal or poorly differentiated). The Gleason score is given as two numbers added together to give a score out of 10 (for example, 3 + 4 = 7). The first number is the most common pattern seen under the microscope and the second number is the next most common. The higher the Gleason score, the more aggressive the cancer, and the faster it is likely to grow. Gleason scores therefore reflect the ‘risk’ posed by the cancer.

Low risk:
Low grade, well differentiated tumour, Gleason score 2–6

Intermediate risk:
Intermediate grade, moderately differentiated, Gleason score 7

High risk:
High grade, poorly differentiated, Gleason score 8–10prostatecancergleasonsThese risk categories are those adopted in the recently announced American Urological Association 2006 Clinical
Practice Guidelines for Localised Prostate Cancer and the National Cancer Control Network Practice Guidelines in Oncology vs
2.2005 Prostate Cancer.See localised prostate cancer guide.pdf
See http://www.nccn.org/patients/patient_guidelines/prostate/files/assets/seo/toc.html

Sources:

Clinical Practice Guidelines: Evidence-based information and recommendations for  the management of localised prostate cancer, A report  of the Australian Cancer  Network  Working Party on Management of Localised  Prostate Cancer, NHMRC, Oct 2002.

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