The New Prostate Cancer Grading System: What You Need to Know
Gleason score, introduced in 1966, is one of the most important prognostic factors in prostate cancer. Treatment decisions are largely dependent upon the Gleason score. It has strong predictive power for pathologic findings at surgery. Many predictive tools utilize the Gleason score.
In an attempt to strengthen the power of the Gleason score, the original 5 tier scoring system underwent modifications in both 2005 and 2014 where scores were instead grouped into a 3 tier system (6, 7, 8–10). However, the system still suffers from weaknesses. The various combinations of scores 3+4=7 vs. 4+3=7 and 8 vs. 9-10 have different outcomes. Additionally, patients can incorrectly perceive a score 6 and being intermediate in the scale when in fact it is on the lower end of the spectrum. Also the scores 3+4=7 and 4+3=7 are often considered to have a similar outcome, when in reality they are very different.
To address these issues, a recent study by Epstein examined more than 20,000 men treated by prostatectomy and 5500 men treated by radiation. Differences in recurrence rates were found between Gleason 3 + 4 and 4 + 3 and between Gleason 8 and 9. A 5 tier system was found to have the best prognostic power.
The new “system has these benefits: more accurate grade stratification than current systems, simplified grading system of five grades, and lowest grade is 1, as opposed to 6, with the potential to reduce overtreatment of prostate cancer.”
Epstein has summarized these findings with excellent images. For pathologists, it is important to incorporate this new system into practice. Urologists, oncologists and radiation oncologists also must be fluent in the modifications. Finally, patients must also be aware. Your pathologist is an important member of your care team. Ask about the pathologist involved in your case. Request a copy of your pathology report. Understand the report. Ask questions.