Several years ago, world-renowned Brady pathologist Jonathan Epstein, M.D., the Rose-Lee and Keith Reinhard Professor of Urologic Pathology, came up with a much-needed solution to confusion in grading prostate cancer: he developed a new grading system called Grade Groups. Epstein and colleagues validated this overhauled system in a large, multi-institutional study. Worldwide, pathologists found it to be such an improvement that it was endorsed by the 2014 International Society of Urological Pathology Consensus Conference.
In the Grade Group system, Grade Group 1 (GG1) is a Gleason score of 6 or lower, GG2 is Gleason score 3+4=7, GG3 is Gleason score 4+3=7, GG4 is Gleason score 8, and GG5 is Gleason score 9-10. “In part, we proposed the new grading system because of anecdotal evidence that Gleason scores were incorrectly combined in the literature,” says Epstein. A big problem: cancer that is Gleason 3 + 4 = 7 is different from cancer that is Gleason 4 + 3 = 7, yet both used to be lumped together as Gleason 7 disease. Gleason 8 cancer is different from Gleason 9 and 10, yet Gleason 8-10 were crammed into the same category in the old system.
There are important differences in these cancers; they have different prognoses and respond differently to treatment. They deserve their own spots in the scoring system. Thus, “the old system was less accurate,” Epstein says.
Guess what? At many hospitals worldwide, Gleason scoring is still less accurate.
In a new study, published in European Urology, Epstein and colleagues looked at how Gleason scores were grouped worldwide. “We found that the most common method in current use was still the D’Amico risk stratification groups (categorized as Gleason < 6, 7, 8–10),” Epstein says, “which is incorrect as it combines Gleason scores, despite very different prognoses.” Things are getting slightly better; in 2016, the authors found, only 10 percent of published articles used Grade Groups or Gleason Score equivalents, and in 2017, this nearly doubled to 19.4 percent.
Unfortunately, says Epstein, “today only a minority of published articles on prostate cancer group Gleason scores accurately. This could lead to inaccurate results and affect patient care with different prostate cancer grades. Our study calls for more widespread adoption of the five Grade Groups.”