What is a Gleason (Prostate-Specific) pattern in a prostate biopsy?

From the Guidelines

A Gleason pattern is a scoring system used to grade prostate cancer cells based on how they appear under a microscope during a prostate biopsy, with the most recent and highest quality study 1 introducing a new prostate cancer grading system that assigns Grade Groups from 1 to 5, derived from the Gleason score. The system assigns a grade from 1 to 5, with 1 being cells that closely resemble normal prostate tissue and 5 being cells that look highly abnormal and aggressive. In practice, pathologists identify the two most prevalent patterns in the biopsy sample and add them together to create the Gleason score (ranging from 6 to 10 in clinically significant cancers). For example, if the most common pattern is grade 3 and the second most common is grade 4, the Gleason score would be 3+4=7. This scoring system is crucial for treatment planning as it helps predict how aggressive the cancer is likely to be. Higher Gleason patterns indicate more aggressive cancer that may spread more quickly, while lower patterns suggest slower-growing cancer. The Gleason pattern assessment is one of the most important prognostic factors in prostate cancer and directly influences treatment decisions, from active surveillance for low-grade cancers to more aggressive interventions for higher-grade disease, as supported by the study 1 which validated the new Grade Group system in two separate cohorts. Some key points to consider when interpreting the Gleason pattern include:

• The new Grade Group system assigns Grade Groups from 1 to 5, derived from the Gleason score, with Grade Group 1 being the least aggressive and Grade Group 5 being the most aggressive.
• The Grade Group system has been validated in several studies, including one with over 26,000 men, and has been shown to predict the risk of recurrence after primary treatment 1.
• The NCCN Guidelines Panel has accepted the new Grade Group system to inform better treatment discussions compared to those using Gleason score alone 1. It's worth noting that while the evidence from older studies 1, 1, and 1 provides a foundation for understanding the Gleason pattern, the most recent and highest quality study 1 provides the most up-to-date and accurate information on the topic.

From the Research

Definition of Gleason Pattern

• The Gleason pattern is a grading system used to evaluate the prognosis of prostate cancer based on the tumor's microscopic appearance 2, 3, 4, 5, 6.
• The system categorizes prostate cancer into different grades based on the pattern of glandular differentiation, with higher grades indicating a worse prognosis.

Gleason Grading Categories

• The Gleason grading system categorizes prostate cancer into several grades, including:
  • Gleason ≤ 6
  • 3 + 4
  • 4 + 3
  • 8
  • 9-10
• These categories are based on the percentage of Gleason patterns 3,4, and 5 present in the tumor 2, 4.

Clinical Relevance of Gleason Pattern

• The Gleason pattern is a strong prognostic parameter in prostate cancer, with higher grades associated with a greater risk of prostate-specific antigen recurrence 2.
• Quantitative Gleason grading, which involves recording the fraction of Gleason patterns 3,4, and 5, can provide clinically relevant information beyond traditional Gleason grading categories 2.
• The Gleason score is one of the most critical predictive factors of prostate cancer, regardless of the therapy used 4.

Evolution of Gleason Grading System

• The Gleason grading system has undergone several modifications since its inception, with the most recent revision implemented by the International Society of Urological Pathology in 2005 and subsequent revision in 2014 3, 5.
• The modified system has resulted in a more accurate grading system for radical prostatectomy, but has complicated the comparison of data before and after the updating 4.