Prostate cancer grading uses two primary systems: the traditional Gleason score (a sum ranging from 6 to 10) and the newer Grade Group system (a scale from 1 to 5).
The Gleason score is determined by a pathologist who examines prostate tissue samples under a microscope.
Grading Individual Patterns: The pathologist assigns a grade from 1 to 5 to the architectural patterns of the cancer cells.
Grade 1 cells look most like normal cells and are least aggressive, while Grade 5 cells look very abnormal and are most aggressive.
In current practice, grades 1 and 2 are rarely used for a cancer diagnosis, so the lowest score assigned is typically 3.
Two grades are assigned to the two most common cell patterns found in the biopsy sample. These two numbers are added together to get the final Gleason score, which typically ranges from 6 to 10.
Importance of Order:
For a score of 7, the order matters. A score of 3+4=7 means the most common pattern is grade 3 (less aggressive) and the second most common is grade 4 (more aggressive), indicating a less aggressive cancer than a 4+3=7 score, where grade 4 is the dominant pattern.
The Grade Group System, Introduced to simplify the grading and provide a more accurate prognosis, the Grade Group system uses a straightforward scale from 1 to 5.
This system is now widely used alongside the Gleason score. Grade Group Gleason Score Description
Grade Group 1 6 or less (3+3) The cancer is likely to grow very slowly, if at all.
Grade Group 2 7 (3+4) The cancer is likely to grow slowly.
Grade Group 3 7 (4+3) The cancer is likely to grow at a moderate rate and is considered more aggressive than Grade Group 2.
Grade Group 4 8 The cancer might grow quickly or at a steady pace.
Grade Group 5 9 or 10 The cells look very abnormal, and the cancer is likely to grow quickly.
The grade (Gleason score and Grade Group), along with the cancer’s stage (TNM system) and the PSA level, helps classify the cancer into risk groups (low, intermediate, or high risk).
This comprehensive assessment is crucial for determining the most appropriate treatment plan, which could range from active surveillance for low-risk cancers to more aggressive treatments like surgery or radiation for high-risk cancers.