What is the significance of the Gleason score in prostate cancer diagnosis?

From the Guidelines

The Gleason score is a crucial grading system used to evaluate the aggressiveness of prostate cancer, ranging from 2 to 10, with higher scores indicating more aggressive cancer, and is used alongside Grade Groups (1-5) to determine treatment options and prognosis. The score is calculated by adding two numbers: the primary grade (representing the most common tumor pattern) and the secondary grade (representing the second most common pattern), each scored from 1 to 5 based on how abnormal the cancer cells appear under a microscope 1. Today, pathologists typically report Gleason scores from 6 to 10, with 6 representing low-grade cancer, 7 indicating intermediate-grade cancer, and 8-10 signifying high-grade, aggressive cancer.

Key Points to Consider

• The Gleason score helps determine treatment options and prognosis, with men with scores of 6 might be candidates for active surveillance, while those with scores of 8-10 typically need more aggressive treatment like surgery, radiation, or hormone therapy 1.
• Modern practice often uses Grade Groups (1-5) alongside the Gleason score, with Grade Group 1 (Gleason 6) having the best prognosis and Grade Group 5 (Gleason 9-10) having the poorest 1.
• The NCCN Guidelines incorporate a risk stratification scheme that uses a minimum of stage, grade, and PSA to assign patients to risk groups, which are used to select the appropriate options that should be considered for treatment and to predict the probability of biochemical failure after definitive local therapy 1.
• Nomograms can be used to inform treatment decision-making for men contemplating active surveillance, radical prostatectomy, neurovascular bundle preservation, or omission of pelvic lymph node dissection (PLND) during radical prostatectomy, brachytherapy, or external beam radiation therapy (EBRT) 1.

Treatment Options

• Active surveillance may be suitable for men with low-grade cancer (Gleason score 6), while more aggressive treatment like surgery, radiation, or hormone therapy may be necessary for those with high-grade cancer (Gleason score 8-10) 1.
• The NCCN Prostate Cancer Panel recommends that NCCN risk groups be used to begin discussing options for treatment of clinically localized prostate cancer and that nomograms be used to provide additional and more individualized information 1.

From the Research

Gleason Score Overview

• The Gleason score is a powerful predictor of outcome in prostate cancer and a cornerstone in counseling and treating patients 2.
• The score is based on the histologic spectrum and variants of the cancer and their prognostic significance.
• The modified Gleason system has resulted in a more accurate grading system for radical prostatectomy, but has complicated the comparison of data before and after the updating 2.

Clinical Predictors of Upgrading

• Clinical factors such as preoperative prostate-specific antigen (PSA), clinical stage, and ultrasound-determined prostate gland volume can predict upgrading to high-grade disease 3.
• Men with low-grade disease at biopsy who have a high PSA level or a large prostate gland volume are at a higher risk of upgrading to high-grade disease 3.

Treatment Options and Outcomes

• The optimal treatment for Gleason score 9-10 prostate cancer is unknown, but treatment with external beam radiotherapy plus brachytherapy boost (EBRT+BT) with androgen deprivation therapy has been associated with significantly better prostate cancer-specific mortality and longer time to distant metastasis compared with EBRT with androgen deprivation therapy or with radical prostatectomy (RP) 4.
• Radical prostatectomy, external beam radiotherapy, and EBRT+BT are all viable treatment options for patients with Gleason score 9-10 prostate cancer, but the choice of treatment should be individualized based on patient characteristics and preferences 4.

Patient Understanding and Shared Decision-Making

• Patient knowledge of the Gleason scoring system is low, even among well-educated and health-literate patients 5.
• Patients' understanding of the importance of the Gleason scoring system is moderate, and is positively associated with Gleason score knowledge 5.
• Enhanced communication and patient-provider communication are needed to maximize shared treatment decision-making and improve patient outcomes 5.