Contemporary Gleason grading and novel Grade Groups in clinical practice

The Gleason grading system provides important information for guiding prostate cancer patients' management and prognostication. The grading system underwent significant modifications over the past decade. In 2005 and more recently in 2014, the International Society of Urological Pathology (ISUP) held two consensus conferences to update prostate cancer grading. Recently, five prognostic grade groups have been proposed to be used in parallel to the Gleason grading system. The purpose of this review is to highlight the key changes in the Gleason grading system and the utility of the grade groups to better reflect biologic behavior for both patients and clinicians.

At the 2014 ISUP consensus conference, prostate cancer Gleason grading was updated and a previously proposed concept of five prognostic grade groups, from 1 to 5 was supported. The Grade Groups, used in parallel to the modified Gleason grading system, translate Gleason scores in five distinct risk categories where Grade Group 1 is defined as Gleason score 6 or less, Grade Group 2 as Gleason score 3 + 4 = 7, Grade Group 3 as Gleason score 4 + 3 = 7, Grade Group 4 as Gleason score 4 + 4 = 8, and Grade Group 5 as Gleason score 9/10. This 5-tiered grade group system better reflects biologic behavior and guides clinical care. The Grade Groups have been endorsed by the ISUP and the World Health Organization. The performance of the Grade Groups has been examined in several recent studies.

This review summarizes developments over the last year in the use of grade groups and outlines their value in clinical practice.