Prostate cancer risk assesment, Gleason and TNM

Prostate cancers' malignancy is graded using the Gleason score. The TNM stage describes how much the cancer has spread. The determination of both Gleason and TNM helps the doctor to evaluate how serious the cancer is and how best to treat it.

Gleason grading system

The histological grade (degree of malignancy) of prostate cancer is determined by a pathologist on the basis of a microscopic examination, using the international Gleason grading system. It is based on the histological grade of the glandular structures of prostate cancer tissue or the difference in appearance compared with a normal structure.

The higher the Gleason score, the greater the difference and the more malignant (aggressive) the cancer. A well-differentiated, nearly normal glandular structure indicates low malignant potential, while a poorly differentiated (very much changed) structure indicates an aggressive cancer. The grade of the change caused by the cancer is evaluated on a scale from 1 to 5, so that the two most prevalent (primary and secondary) patterns are separately graded from the sample of cancer tissue. These figures are added up, giving the final Gleason score.

In theory, the Gleason score can vary from 2 to 10, with 10 being the worst score. After the introduction of current advanced techniques in pathological diagnosis, it became evident that low Gleason scores are practically not found in prostate cancer. Thus, Gleason scores for prostate cancer usually range from 6 to 10. The score 6 usually indicates a good prognosis. Approximately 70% of patients with a Gleason score of 6 have a localised prostate cancer.

Very high Gleason scores (8 to 10) indicate an aggressive high-risk cancer. If the Gleason score is 8 or higher, the prostate cancer has often already spread at the time of diagnosis. A higher risk also indicates a higher recurrence tendency. This is taken into account in the individual implementation of treatment. Nowadays, advanced prostate cancer can be effectively treated with various combinations of radiotherapy and drugs.

Gleason grading

Gleason score

Meaning

6

The cells are well differentiated, meaning they look similar to healthy cells. This means that he cancer usually grows slowly and is less aggressive. Thus, the prognosis is generally good.

7

The cells are moderately differentiated, meaning they look somewhat similar to healthy cells. This a medium-risk prostate cancer that can grow rapidly.

8-10

The cells are poorly differentiated or undifferentiated, meaning they look very different from healthy cells. This is an aggressive high-risk prostate cancer that grows rapidly, metastasises easily and has a higher recurrence tendency.

Gradus

In the older WHO classification, prostate cancers are classified into grades 1-3 according to the degree of differentiation of the cells. The classification is thus cytological.

Gradus

Gradus

Meaning

1

The cancer is well differentiated.

2

The cancer is moderately differentiated.

3

The cancer is poorly differentiated.

TNM Staging

The TNM stage describes how much the cancer has spread. The letters T, N and M stand for Tumour, Node and Metastasis. The stage is based on the results of diagnostic tests, examinations and imaging. The TNM staging is as follows:

TNM staging

Tumour (T)

Meaning

T0

No evidence of primary tumour.

T1

The cancer is too small to be seen on a scan, or felt during examination of the prostate.

T1a

Your surgeon unexpectedly finds T1a cancers during surgery for other reasons. The cancer is in less than 5 % of the removed tissue.

T1b

Your surgeon unexpectedly finds T1b cancers during surgery for other reasons. The cancer is in 5% or more of the removed tissue.

T1c

The cancer is found by biopsy, for example after a raised PSA level.

T2

The cancer is completely inside the prostate gland..

T2a

The cancer is in only half of one side of the prostate gland.

T2b

The cancer is in more than half of one side of the prostate gland, but not both sides.

T2c

The cancer is in both sides but is still inside the prostate gland.

T3

The cancer has broken through the capsule (covering) of the prostate gland.

T3a

The cancer has broken through the capsule (covering) of the prostate gland.

T3b

The cancer has spread into the tubes that carry semen (seminal vesicles).

T4

The cancer has spread into other body organs nearby, such as the back passage, bladder, or the pelvic wall.

Node (N)

Meaning

NX

Regional lymph nodes cannot be assessed.

N0

The nearby lymph nodes don’t contain cancer cells.

N1

There are cancer cells in lymph nodes near the prostate.

Metastasis (M)

Meaning

MX

Distant metastasis cannot be assessed.

M0

The cancer hasn’t spread to other parts of your body.

M1

The cancer has spread to other parts of the body outside the pelvis.

M1a

There are cancer cells in lymph nodes outside the pelvis.

M1b

There are cancer cells in the bone.

M1c

There are cancer cells in other parts of the body.

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