Rigi10™ Malleable Penile Prosthesis
Also Known As
Gleason grade, Gleason sum, Gleason grading system, Gleason pattern, ISUP Grade Group system, prostate cancer grade
Definition
The Gleason score is a grading system used to determine the aggressiveness of prostate cancer based on how abnormal the cancer cells in a biopsy sample look under a microscope and how quickly they are likely to grow and spread.1 It is calculated by adding together the two grades of cancer cells that make up the largest areas of the biopsied tissue sample.2 The Gleason grade is primarily based on the architecture or arrangement of the malignant cells within the tumor as well as other factors such as the degree of differentiation.3
In this system, pathologists assign a grade from 1 to 5 to the cancer cells based on how much they resemble normal prostate tissue:
- Grade 1 means the cells look almost like normal prostate cells
- Grade 5 means the cells look very different from normal prostate cells4
Since prostate cancers often have areas with different grades, the Gleason score is determined by adding the two most common grades found in the sample. For example, if the most common pattern is grade 3 and the second most common is grade 4, the Gleason score would be written as 3+4=7.5 If only one pattern is present, that grade is doubled.
The Gleason score typically ranges from 6 to 10, with higher scores indicating more aggressive cancer that is more likely to grow and spread quickly.2 Scores of 6 or less are considered low-grade (well-differentiated), 7 is intermediate-grade (moderately differentiated), and 8-10 are high-grade (poorly differentiated).6
In 2014, the International Society of Urological Pathology consensus conference recommended a new five-tier Grade Group system based on the Gleason score:
- Grade Group 1: Gleason score 6 or less (low-grade cancer)
- Grade Group 2: Gleason score 3+4=7 (medium-grade cancer)
- Grade Group 3: Gleason score 4+3=7 (medium-grade cancer)
- Grade Group 4: Gleason score 8 (high-grade cancer)
- Grade Group 5: Gleason score 9-10 (high-grade cancer)3,7
This system was developed to better reflect the biological behavior of prostate cancer and to address potential confusion caused by the lowest commonly assigned score being 6 out of a theoretical 2-10 scale.8
Clinical Context
The Gleason score is a critical component in the clinical management of prostate cancer, used to help determine prognosis and guide treatment decisions.1 It is typically used in conjunction with other clinical parameters such as prostate-specific antigen (PSA) levels and clinical staging to risk-stratify patients and develop appropriate treatment plans.2
The scoring system is applied after a prostate biopsy is performed, usually prompted by an elevated PSA level, abnormal digital rectal examination, or other clinical indications.3 During the biopsy procedure, multiple core samples are taken from different areas of the prostate gland and examined by a pathologist who assigns the Gleason grades.4
Clinical significance of different Gleason scores:
- Gleason score 6 (Grade Group 1): Generally indicates low-risk cancer with favorable prognosis. Patients with this score may be candidates for active surveillance rather than immediate intervention, depending on other clinical factors.5
- Gleason score 7: Intermediate-risk cancer, with 3+4=7 (Grade Group 2) having a better prognosis than 4+3=7 (Grade Group 3). The distinction is important as it may influence treatment decisions between active surveillance and more definitive therapies like surgery or radiation.6
- Gleason scores 8-10 (Grade Groups 4-5): High-risk cancers that typically require more aggressive treatment approaches. These cancers have a higher likelihood of extraprostatic extension, metastasis, and cancer-specific mortality.7
Several prognostic nomograms incorporate the Gleason score along with PSA level and clinical staging to assist in patient counseling by better classifying risk aggressiveness. These include the Partin tables from Johns Hopkins University, the Memorial Sloan Kettering Cancer Center (MSKCC) nomograms, and the Cancer of the Prostate Risk Assessment (CAPRA) score from the University of California at San Francisco.8
The Gleason score has proven to have significant prognostic value, with higher scores correlating with worse outcomes including increased risk of biochemical recurrence after treatment, metastasis, and prostate cancer-specific mortality.9 However, it’s important to note that there can be interobserver variability in Gleason grading, even among experienced pathologists, which has led to efforts to standardize the grading process through computerized analysis programs and artificial intelligence techniques.10