Prostate Cancer Risk Assessment Based on Gleason Score

Introduction to Gleason Score

The Gleason score is the most critical histopathologic predictor of prostate cancer aggressiveness, determined by adding the two most dominant cancer patterns to create a score ranging from 6-10, with higher scores indicating more aggressive disease and worse prognosis, as recommended by the National Comprehensive Cancer Network 1, 2

The pathologist identifies the most dominant Gleason pattern and the pattern with the highest grade to calculate the Gleason score, according to the Annals of Oncology 1
The two most common patterns are added together, though tumors with a tertiary Gleason grade 4 or 5 behave more aggressively than the sum of the two dominant patterns alone, as stated in the Annals of Oncology 1

The International Society of Urological Pathology introduced a simplified Grade Group system that correlates with Gleason scores, as recommended by the National Comprehensive Cancer Network 2
Grade Group 1: Gleason score ≤6, only individual discrete well-formed glands, as defined by the National Comprehensive Cancer Network 2
Grade Group 2: Gleason score 3+4=7, predominantly well-formed glands with lesser component of poorly formed/fused/cribriform glands, as defined by the National Comprehensive Cancer Network 2
Grade Group 3: Gleason score 4+3=7, predominantly poorly formed/fused/cribriform glands with lesser component of well-formed glands, as defined by the National Comprehensive Cancer Network 2
Grade Group 4: Gleason score 8, only poorly formed/fused/cribriform glands or mixed patterns, as defined by the National Comprehensive Cancer Network 2
Grade Group 5: Gleason score 9-10, lack of gland formation with or without necrosis, as defined by the National Comprehensive Cancer Network 2

Very Low Risk: Clinical stage T1c, Gleason score ≤6, PSA <10 ng/mL, <3 biopsy cores positive, ≤50% cancer in each core, PSA density <0.15 ng/mL/g, with a 5-year biochemical recurrence-free survival after radical prostatectomy of 96%, as recommended by the Journal of Urology and the National Comprehensive Cancer Network 2, 4
Low Risk: Clinical stage T1-T2a, Gleason score ≤6, PSA <10 ng/mL, with a 10-year prostate cancer-specific mortality on active surveillance of 2.4%, as recommended by the Annals of Oncology and the Journal of Urology 1, 4
Intermediate Risk (Favorable): Gleason score 3+4=7, PSA <10 ng/mL, with a 5-year biochemical recurrence-free survival after radical prostatectomy of 88%, as recommended by the National Comprehensive Cancer Network 2
Intermediate Risk (Unfavorable): Gleason score 3+4=7, PSA 10-20 ng/mL, OR Gleason score 4+3=7, PSA <20 ng/mL, with a 5-year biochemical recurrence-free survival after radical prostatectomy for Grade Group 3 of 63%, as recommended by the Journal of Urology and the National Comprehensive Cancer Network 2, 4
High Risk: Any of clinical stage T3-T4, OR Gleason score 8-10, OR PSA >20 ng/mL, with a 5-year biochemical recurrence-free survival after radical prostatectomy for Grade Group 4 of 48% and Grade Group 5 of 26%, as recommended by the Annals of Oncology and the Journal of Urology 1, 2, 4

The pathology report must include the maximum length of cancer involvement in each core, the most common and worst Gleason grades, the extent of tumor involvement in each biopsy core, and the number of positive cores and percentage of involvement, as recommended by the Annals of Oncology 1, 7