The prostate biopsy Gleason score is a relatively accurate predictor of pathologic findings and disease-free survival, according to a study by V. Narain D.J. Grignon and other researchers published on PubMed. Results of the study placed the overall accuracy of the popular grading system at 58.3 percent, suggesting reasonable reliability.
The Gleason grading system for prostate cancer is widely used both in the United States and the rest of the world, according to Peter A. Humphrey writing for Nature. Less prevalent competing grading systems include the type used by the World Health Organization.
The system was developed by Dr. Donald F. Gleason, a Minnesota pathologist, and the Veterans Administration Cooperative Urological Research Group, explains Humphrey. During development, the Gleason grading system was tested on about 5,000 prostate cancer patients in random clinical trials that were accompanied by long-term follow-up, explains Humphrey. This rigor underlies the popularity of the ranking method.
The Gleason grading system is based on certain patterns formed by prostate cancer cells at various periods of development, notes Humphrey. These patterns are uncovered through hematoxylin and eosin staining. Divided into five basic grades, these patterns are combined with complementary secondary grade patterns to produce scores of between two and 10.
Despite the relative reliability, the Gleason grading system has some weaknesses, cautions Humphrey. Results can be influenced by subjective factors, such as pathologist experience, and the method is unsuitable for use on the form of prostate cancer that afflicts the urothelial and squamous cells.