When the prostate is biopsied, its samples are taken then studied under a microscope by a specialized and highly experienced doctor known as a pathologist. The pathologist sends your doctor the biopsy report which gives a diagnosis of each sample taken. Information on the report is taken to manage an appropriate treatment care. In order to understand a biopsy report, you need to understand what Gleason score or Gleason grade is.
A common prostate biopsy is the core needle biopsy. In this procedure, the doctor inserts a hollow needle in the prostate glands and as it is pulled out, small cylindrical prostate tissues known as the core are removed. This is repeated on different areas of the prostate.
The pathologist report analyzes each core separately and assigns a letter to it. If a tumor or any other problem is found, it is often not in all cores, therefore, the doctor needs to analyze all the cores to know what exactly is going on with you.
What is Gleason score?
Pathologists use numbers to grade prostate cancer. The numbers form 1-5 are based on how much the cancerous tissue look like normal tissue when viewed under a microscope. This is known as the Gleason system. The grades one and two are not used often in biopsies; most fusion biopsy samples grade from 3 and above.
· If the cancerous tissue looks almost like a normal prostate tissue, it is assigned grade 1.
· If the cancer cells and the growth pattern looks very abnormal, it is assigned grade 5.
· Grade 2-4 have features in between the two extremes.
Prostate cancer has areas with different grades and a grade is assigned to the both areas that make up most of the cancer. The two grades are added to give the Gleason score, also known as Gleason sum. The first number in Gleason score represents the grade that is most common in the tumor. Example, a Gleason score of 3+4=7 means most of the tumor is grade 3, the less tumor is grade 4 and the Gleason score is 7. The highest Gleason score is 10.
Gleason score can also be represented as 7/10, 7(3+40) or just the combined Gleason score of 7.
The higher the Gleason score, the more likely that the cancer will grow and spread quickly.
What it means to have a Gleason score of 6 or 7 or 8-10
The lowest Gleason score that can be found on a prostate biopsy is 6. This cancer is called low grade or well differentiated and they are less aggressive; they grow and spread slowly.
Cancer with a Gleason score of 8-10 is called high grade or poorly differentiated. The cancer is aggressive which means it is likely to grow and spread quickly.
Cancer with a Gleason score of 7 is has an intermediate grade and it is moderately differentiated. The rate of its growth is between the above two extremes.