Prostate adenocarcinoma grade group 1: rationale for retaining a cancer label in the 2022 World Health Organization Classification

The Gleason system forms the basis for prostate cancer grading worldwide. It has been modified on several occasions, most recently after the International Society of Urological Pathology (ISUP) consensus conferences in 2005, 2014, and 2019, and the 2019 white paper by the Genitourinary Pathology Society. At the 2014 ISUP conference the concept of grade groups (GG1–GG5) was introduced, also referred to as ISUP grade, World Health Organization [WHO] grade, or simply grade groups. Grade groups are based on Gleason scores and have some advantages with respect to communication of results to patients, clinicians, and researchers. Grade groups offer the advantage of appropriately assigning the lowest rank (GG1) to Gleason score (GS) 3 + 3 = 6 cancers to emphasize their generally low risk in the proper clinical context (eg, prostate-specific antigen [PSA] <10 ng/ml and clinical stage ≤cT2a).