Gleason Score – What Should You Know About It?

Back in 1960s a pathologist named Donald Gleason came up with a grading system which is now referred to as Gleason score. It helps in determining the outlook and prognosis of prostate cancer. After biopsy of prostate gland, doctors today may use the Gleason score to get a clearer picture. It also helps in assessing the cancer metastasis and determining the required treatment protocol in response.

Gleason proposed that there may be 5 patterns by which normal cells change into cancerous cells, and on this basis, he devised a grading system from 1 to 5. Cells that are graded as 1 or 2 are acknowledged as the tumor cells of particularly low grade and may look rather similar to the normal ones, whereas cells of grade 5 are acknowledged as high graded tumor cells. When compared to those of grade 1 or 2, grade 5 cells are vastly mutated and look nothing like the normal cells.

For biopsy, several samples are collected from different prostate areas as there are chances that the prostate cancer may have metastasized. After a microscopic exam, the doctor may find 2 areas particularly dense with cancer cells. This is where Gleason score comes into the picture to grade the cells of these areas from 1 to 5, separately. The scores are added together to get the combined value, often called Gleason sum. In case the microscopic examination of the sample reveals 3 different grades or an escalating number of grade 5 cancerous cells, the Gleason score may be subjected to certain modifications.

Assessment Of Results

• The Gleason score of a person is calculated between 2 and 10. The rule of thumb is, higher the grade, the aggressive the cancer is.
• A score or grade of 6 is considered as the lowest possible Gleason score. Therefore, a prostate cancer with a Gleason score of 6 is defined as a low grade or well-differentiated cancer i.e. it will be a slow growing lesion or tumor.
• Cancers with scores ranging from 8 to 10 are considered as high grade or poorly-differentiated cancers. The growth here is rather aggressive.
• Score 7 may be outcome of the following two results:

• 3+4=7 - this outcome usually suggests a good outlook
• 4+3=7 - this outcome suggests a comparatively quicker growth which is less than that of score 8.

Alternative Approaches For Measuring Prostate Cancer

Even when Gleason score assists the doctors to opt the desired treatment protocol, nonetheless following factors may also help make the matters even easier.

• PSA levels in blood
• Imaging test results
• Rectal exam results
• The number of biopsy samples showing positive results for cancer
• Cancer metastasis
• Presence of cancer on either or both sides of prostate

Previously Gleason score was divided into 3 groups: 6, 7 and 8-10. But 9 and 10 are rather high grade with worsened outlook as compared to score 8 cancer; despite of being in one group. Therefore, recent groupings seem more understandable in which grade 1 is considered best and grade 5 is considered worst. These are given as:

• Grade 1: Gleason 6 or below
• Grade 2: Gleason 3+4=7
• Grade 3: Gleason 4+3=7
• Grade 4: Gleason 8
• Grade 5: Gleason 9-10

The Gleason score suggests the type of treatment approaches and protocols. For low scores, the treatment options may be:

• Active surveillance
• Radiation therapy
• Radical prostatectomy

For high scores the treatment options may be:

• External beam radiation
• Brachytherapy
• Combination of the above two
• Radical prostatectomy
• Active surveillance
• Chemotherapy
• Hormone therapy
• Surgery

References

• Epstein, J. I., Zelefsky, M. J., Sjoberg, D. D., Nelson, J. B., Egevad, L., Magi-Galluzzi, C., ... & Eastham, J. A. (2016). A contemporary prostate cancer grading system: a validated alternative to the Gleason score. European urology, 69(3), 428-435.
• Heidenreich, A., Bastian, P. J., Bellmunt, J., Bolla, M., Joniau, S., van der Kwast, T., ... & Mottet, N. (2014). EAU guidelines on prostate cancer. Part 1: screening, diagnosis, and local treatment with curative intent—update 2013. European urology, 65(1), 124-137.