I don't recall ever hearing the term.. So for others like me:
A pathologist examines the biopsy specimen and attempts to give a score to the two patterns.
First called the primary grade, represents the majority of tumor (has to be greater than 50% of the total pattern seen).
Second - a secondary grade - relates to the minority of the tumor (has to be less than 50%, but at least 5%, of the pattern of the total cancer observed).
These scores are then added to obtain the final Gleason score.
Increasingly, pathologists provide details of the "tertiary" component. This is where there is a small component of a third (generally more aggressive) pattern. So there could be a Gleason 3+4 with a tertiary component of pattern 5 - this would be considered to be more aggressive than a prostate cancer that was Gleason 3+4 with no tertiary pattern 5.
Post Edited (davidg) : 4/12/2011 7:27:31 PM (GMT-6)
Thanks John, that makes sense.
The whole Gleason system appears to be somewhat variable as it is not as clear cut as we patients would like. My docs all said we treat it as if it were a bit worse than it is showing in the biopsy, scans, DRE, etc.
This is in lline with Meyers , who contends that the cancer is usually worse than the diagnostics are showing, thus his more aggressive approach.