Grading of prostatic adenocarcinoma: current state and prognostic implications

Abstract

Background: Despite significant changes in the clinical and histologic diagnosis of prostate cancer, the Gleason grading system remains one of the most powerful prognostic predictors in prostate cancer. The correct diagnosis and grading of prostate cancer is crucial for a patient's prognosis and therapeutic options. However, this system has undergone significant revisions and continues to have deficiencies that can potentially impact patient care.

Main body: We describe the current state of grading prostate cancer, focusing on the current guidelines for the Gleason grading system and recent changes from the 2014 International Society of Urological Pathology Consensus Conference on Gleason Grading of Prostatic Carcinoma. We also explore the limitations of the current Gleason grading system and present a validated alternative to the Gleason score. The new grading system initially described in 2013 in a study from Johns Hopkins Hospital and then validated in a multi-institutional study, includes five distinct Grade Groups based on the modified Gleason score groups. Grade Group 1 = Gleason score ≤6, Grade Group 2 = Gleason score 3 + 4 = 7, Grade Group 3 = Gleason score 4 + 3 = 7, Grade Group 4 = Gleason score 8, Grade Group 5 = Gleason scores 9 and 10.

Conclusion: As this new grading system is simpler and more accurately reflects prostate cancer biology, it is recommended by the World Health Organization (WHO) to be used in conjunction with Gleason grading.

Fig. 1

The original Gleason Grading system diagram

Fig. 2

a Gleason score 3 + 3 = 6 (Grade Group 1). b Gleason score 3 + 4 = 7 (Grade Group 2) with minor component of cribriform glands. c Gleason score 4 + 4 = 8 (Grade Group 4) with irregular cribriform glands. d Gleason score 4 + 4 = 8 (Grade Group 4) with fused glands with cytoplasmic vacuoles. e Gleason score 4 + 4 = 8 (Grade Group 4) with glomeruloid glands. f Gleason score 4 + 4 = 8 (Grade Group 4) with poorly-formed glands

Fig. 3

a Gleason score 5 + 5 = 10 (Grade Group 5) with solid sheets of cells. b Gleason score 5 + 5 = 10 (Grade Group 5) with cords of cells. c Gleason score 5 + 5 = 10 (Grade Group 5) with individual cells. d Gleason score 5 + 4 = 9 (Grade Group 5) with cribriform glands, some with necrosis. e Intraductal carcinoma with necrosis (left), surrounded by basal cells highlighted by p63 and high molecular weight cytokeratin (right) and positive for racemase. f Mucinous adenocarcinoma Gleason score 3 + 4 = 7 (Grade Group 2) with individual well-formed glands and minor component of cribriform glands floating in extracellular mucin