Prostate Cancer Grading and Treatment

Introduction to Gleason Score

The Gleason score is a grading system that ranges from 6 to 10, determined by adding the two most dominant cancer patterns seen on prostate biopsy, with higher scores indicating more aggressive disease that requires more intensive treatment, as recommended by the American Urological Association 1, 2
The pathologist assigns a grade from 1 (least aggressive) to 5 (most aggressive) based on the architectural differentiation of cancer cells, then combines the most predominant pattern with either the second most predominant pattern or the highest grade present to create the final score, according to the International Society of Urological Pathology 3
When three grades are present, the highest grade and the dominant grade should be used, as suggested by the British Journal of Cancer 4

Risk categories integrate Gleason score with PSA level and clinical stage, with the American College of Radiology recommending the following risk stratification: Very Low Risk (Gleason ≤6, PSA <10 ng/mL, clinical stage T1c), Low Risk (Gleason ≤6, PSA <10 ng/mL, clinical stage T1-T2a), Intermediate Risk (Gleason 3+4=7, PSA <10 ng/mL), and High Risk (Gleason 8-10, OR PSA >20 ng/mL, OR clinical stage T3-T4) 1, 3
The 5-year biochemical recurrence-free survival rates are: 96% for Very Low Risk, 88% for Intermediate Risk (Favorable), 63% for Intermediate Risk (Unfavorable), 48% for High Risk (Grade Group 4), and 26% for High Risk (Grade Group 5) 2

For patients with Gleason 8-10 (high-risk disease), aggressive definitive treatment is mandatory if life expectancy ≥5 years, consisting of either radical prostatectomy with pelvic lymph node dissection OR external beam radiation therapy plus 2-3 years of androgen deprivation therapy, as recommended by the National Comprehensive Cancer Network 1, 5
For Gleason 7 disease, treatment depends on the predominant pattern and life expectancy, with the European Association of Urology recommending radical prostatectomy OR radiation therapy (with or without brachytherapy; with or without hormone therapy for 4-6 months) for life expectancy ≥10 years, and observation or treatment options for life expectancy <10 years 1
For Gleason ≤6 disease, active surveillance OR definitive treatment (radical prostatectomy or radiation therapy) is recommended for life expectancy ≥10 years, and active surveillance is appropriate for life expectancy <10 years, as suggested by the American Society of Clinical Oncology 1

The pathology report must include the maximum length of cancer involvement in each core, most common and worst Gleason grades, extent of tumor involvement in each biopsy core, number of positive cores and percentage of involvement, and presence of extraprostatic extension, as recommended by the College of American Pathologists 1, 2, 5

After radical prostatectomy, PSA should fall below detection level within 2 months, and consider adjuvant therapy if adverse pathological features are identified, as recommended by the American Urological Association 5