Prostate cancer grading in 2018: limitations, implementations, cribriform morphology, and biological markers.

The Gleason grading system is among the most important prognostic factors in patients with prostate cancer. From the 2005 to the 2014 consensus conferences, organized by the International Society of Urological Pathology, the morphologic criteria for the identification of the Gleason patterns were redefined, thus resulting in the shrinkage of the Gleason pattern 3. This led to the expansion of the Gleason pattern 4. The newly proposed grade group system reduces the Gleason scores of prostate cancer to the lowest number, each associated with a unique behavior from the prognostic point of view. The advantage is that the simplified system with five groups allows for a more accurate stratification of the patients in comparison with the Gleason system. Cribriform, fused, ill-defined and glomeruloid glands are part of the histologic spectrum of the Gleason pattern 4. Cribriform morphology has a prognosis that is worse in comparison with the other non-cribriform Gleason 4 patterns. One of the major implications of the cribriform growth is that it precludes a patient from choosing active surveillance.