The histopathologist looks at the cancer cells and will decide how aggressive they are

Aggressiveness ranges from grade G3 (least aggressive) to grade G5 (most aggressive)

The Gleason grade assesses how similar the cancer cells are to normal cells

The Gleason score is the sum of the two most common grades

The Gleason score gives an idea how likely the cancer is to spread

The Gleason score ranges from:

   6 = least aggressive well differentiated prostate cancer

   7 = moderately aggressive moderately differentiated cancer

   8-10 = more aggressive poorly differentiated cancer

The Gleason score is made up of the most common grade plus the highest grade elsewhere

It can be 6 (3+3), 7 (3+4 or 4+3) or 8-10 (combination of 4s or 5s)

The higher the score the more aggressive the cancer might be.

The more aggressive the cancer is, the more likely it is to spread