There is a huge variation in prostate cancers, with some very aggressive forms that require speedy treatment, and other slow-growing forms that don’t present a significant risk in the short or medium term.
The Gleason Score (or Gleason Grading system) is a very reliable way of measuring your prostate cancer to determine how severe it is and predicting the outcome.
Cells taken from the prostate by a pathologist (through a procedure called a prostate biopsy)are viewed under a microscope, and calculations are made based on their appearance, allowing a score or grade to be put on your prostate cancer.
Prostate cells can be identified from other cells, so abnormalities are easy to spot. Low-grade cancer cells often look only slightly different from healthy cells, whilst the most aggressive cancer cells look completely unlike normal prostate cells (or any other kind of cells).
Therefore the more distorted and aggressive the cancer looks, the higher the Gleason grade, and the more aggressive the cancer behaves in the body.
If prostate cancer is suspected, a prostate-specific antigen (PSA) blood test will be taken: this measures the concentration of this enzyme in the blood. But a Gleason score can’t be determined by a PSA test alone – your PSA level will indicate whether a prostate biopsy is needed.
A Prostate Biopsy is a routine procedure.
A prostate biopsy is the removal of a small, cylindrical sample of tissue from inside the gland, using hollow tubes inserted through the back passage. These slivers of tissue are studied under a microscope and after calculating various readings a Gleason score, generally of between 2 and 10, will be assigned to the core samples.
A Gleason score of 3 is certainly the most common, and men with these cancers usually have fairly good prospects. A Gleason score of 7 is nearly always is an intermediate risk.
If the prostate biopsy results indicate a need to remove the prostate, after surgery the gland will be dissected in the laboratory to confirm this earlier score and determine whether further treatment is required. With the entire gland to examine, the new Gleason score may not be exactly the same as the prostate biopsy results, being either higher or lower.
Understanding How the Gleason Scale Works
The lowest number on the Gleason grade scale is 1 and the highest is 5. Two Gleason grade numbers are actually determined and then added up to get the final Gleason score.
Examining the samples of tissue from the biopsy through a microscope, the pathologist looks for the most common type of cell in your tumour and calls them the primary grade, and then calls the next most common type the secondary grade. One score is given for the primary grade and another for the secondary grade – from 1 to 5 in each case. The Gleason score is the sum of the two grades, so the total score can be anything from a 2 (1 + 1) to a 10 (5 + 5). The Gleason score is usually given with the primary cancer number first, and the secondary cancer number second.
The Lower the Score, the better, this is what the scores mean:
- 2 to 4 – very low cancer aggression, likely to grow very slowly
- 5 to 6 – mildly aggressive,
- 7 – the cancer is moderately aggressive and will grow at a moderate rate
- 8 to 10 – the cancer is highly aggressive.
A combined Gleason score of 10 is grave, although there are still many treatments possible.
However, not all Gleason scores are equal. It’s possible for the secondary grade to score higher than the primary grade, which means that the cancer has not advanced as far with cellular deterioration. So it’s important to know the two numbers that comprise the score, and the order of them.
Conclusions from the Gleason Score
A low Gleason score in an older man, or in the early stage of prostate cancer may suggest monitoring rather than surgery or radiotherapy, as the cancer may not spread or majorly impact upon health.
A high Gleason score in a younger man, or a more advanced stage of prostate cancer is more likely to suggest active intervention.