Interpreting the Pathology Report and Gleason Score
The two major components of the pathology report from a random 12-core biopsy are the Gleason score, which measures how aggressive the tumor appears, and the quantity of cancer in the 12-core specimen.
What Is The “Gleason Grade” Or “Gleason Score”?
The Gleason grading system assigns a “pattern” to the cancer cells, depending upon their appearance under the microscope. The patterns are graded from 1 to 5. The pathologist assigns a higher number when the appearance of the cancer cells deviates more from the visual appearance of normal prostate gland tissue. The first number in the score is the grade that applies to the most common type of cancer seen in the biopsy. The second number in the score is the next most common grade. These two different grades are then added together to yield the Gleason score. In actual practice, the Gleason score only ranges between 6 and 10. Therefore, a Gleason 6 is the lowest, most favorable grade possible.
What Does It Mean to Have a Gleason Score of 7?
A Gleason score of 7 can mean 3+4=7 or 4+3=7, depending on whether grade 3 pattern or grade 4 pattern is predominant. The biggest therapeutic difference between these grades is that more aggressive radiation therapy protocols are often recommended for Gleason scores of 4+3=7 and higher.
What Does It Mean to Have Gleason Scores of 8 to 10?
Gleason score 8 cancers are aggressive, and Gleason score 9 to 10 cancers are more so. However, some patients with Gleason scores 9 or 10 can still be cured. The actual outlook for a specific patient also depends on additional factors, such as PSA, clinical stage, and the extent of cancer on biopsy.
Can the Biopsy Gleason Score Determine the Grade in the Entire Prostate?
The Gleason score on biopsy usually reflects the cancer’s true grade. However, in about 25 percent of cases the biopsy underestimates the true grade, resulting in under grading. Somewhat less commonly, over-grading occurs. This occurs when the true grade of the tumor is lower than that which is seen in the biopsy.
How Can Patients Be Sure the Reported Gleason Grade Is Accurate?
Assigning the correct Gleason score is developed through experience and practice. It is often prudent to submit the biopsy material for a second opinion to a center managing large numbers of patients with prostate cancer, to confirm the accuracy of the initial Gleason score.
Concluding Thoughts
A few years ago, there was a news story about a polar bear attacking a man in Canada. Shockingly, the report said that the bystanders did nothing to help the poor man. However, upon further review it turned out that the reporter had neglected to report that the bear was only a cub, whose reach was lower than the man's knees. When facing a monstrous behemoth like cancer, the most important question to ask is "What kind of cancer am I dealing with?"
Jonathan Epstein, MD received his doctorate from Boston University. Following his residency in anatomic pathology at The Johns Hopkins Hospital in Baltimore, Maryland, and a fellowship in oncologic pathology at Memorial Sloan Kettering Cancer Center in New York., he then joined the staff at The Johns Hopkins Hospital and has been there his entire career. At the Johns Hopkins Medical Institutions, he is Professor of Pathology, Urology, and Oncology; the recipient of the Reinhard Chair of Urological Pathology; and Director of Surgical Pathology. He is the past president of the International Society of Urological Pathology. Dr. Epstein has 744 publications in peer-reviewed literature and has authored 50 book chapters with a H-factor of 118. His most-frequently cited first or last authored publications is ‘‘Pathological and Clinical Findings to Predict Tumor Extent of Nonpalpable (stage T1c) Prostate Cancer,’’ published in JAMA, which established the criteria for active surveillance.