What is the Gleason score in prostate cancer?

From the Guidelines

The Gleason score is a grading system used to evaluate the aggressiveness of prostate cancer, ranging from 2 to 10, with higher scores indicating more aggressive cancer. The score is determined by a pathologist who examines tissue samples from a prostate biopsy under a microscope, assigning two grades from 1 to 5 to the most common and second most common cancer patterns seen, then adding these numbers together to create the Gleason score 1.

Key Points to Consider

• Modern practice typically uses scores from 6 to 10, with 6 considered low-grade cancer, 7 as intermediate-grade, and 8-10 as high-grade cancer.
• A Gleason score of 7 can be further specified as 3+4=7 or 4+3=7, with the latter indicating more aggressive disease.
• The Gleason score helps doctors determine appropriate treatment options and predict the likely outcome for patients with prostate cancer, guiding decisions about whether to pursue active surveillance, surgery, radiation therapy, or other treatment approaches 1.
• Recent studies have introduced the Grade Group system, which has been accepted by the NCCN Panel to inform better treatment discussions compared to using the Gleason score alone 1.

Clinical Application

• The Gleason score is an essential component of risk assessment, helping to stratify patients into very low-, low-, intermediate-, high-, and very high-risk groups.
• Heterogeneity exists within each risk group, and factors such as primary Gleason pattern, number of positive biopsy cores, and presence of intermediate-risk factors can affect outcomes 1.
• The most recent and highest quality study recommends using the Grade Group system to guide treatment decisions, as it has been shown to predict the risk of recurrence after primary treatment 1.

From the Research

Gleason Score Overview

• The Gleason score is a key component of a prostate cancer diagnosis, indicating disease aggressiveness 2
• It serves as a risk communication tool that facilitates shared treatment decision-making 2
• The system is highly complex and difficult to communicate, which can undermine well-informed and high-quality shared treatment decision-making 2

Gleason Score and Prostate Cancer Outcomes

• Changes in Gleason grading have affected the long-term outcomes of prostate cancer patients 3
• Revised Gleason scores have improved outcomes in all risk groups, with a consistent increased risk in biochemical failure, metastatic disease, and prostate cancer-related death with each successive grade 3
• Apparent diffusion coefficient (ADC) and ADC ratios have been found to correlate significantly with Gleason score and predict high-grade prostate cancer 4

Treatment Outcomes Based on Gleason Score

• For patients with biopsy Gleason Score 9-10, no significant difference in cancer-specific mortality was observed after radical prostatectomy vs. external beam radiation therapy 5
• However, in patients who underwent radical prostatectomy without adjuvant radiation therapy, a minor improvement in cancer-specific survival was observed compared to external beam radiation therapy 5
• In patients with pathologically organ-confined tumors, the specimen Gleason score is the only predictor of disease-free survival 6

Gleason Score and Patient Understanding

• Patient knowledge of the Gleason scoring system is generally low, despite being well-educated and health literate 2
• Patients' understanding of the importance of the Gleason scoring system is moderate and positively associated with Gleason score knowledge 2
• Enhanced communication is needed to maximize shared treatment decision-making and improve patient understanding of the Gleason scoring system 2