How is the Prostate Gleason Score Graded? Your Biopsy and Gleason Score Part 2

Geoff McLennan, Prostate Cancer Survivor and Advocate

In part one of this blog series, I explained the different types of prostate biopsies available today. In part two, I will explain how the biopsy is used to determine what is known as the Gleason score.

---

The prostate Gleason Score

Developed by Howard Gleason, M.D. around 1963, the Gleason Score was a critical change in prostate cancer (PCa) diagnosis, which many years ago had been determined primarily by the somewhat unreliable PSA test or the DRE.

Prostate biopsy tissue samples are sent to a pathologist who specializes in grading or providing the Gleason score. Your pathologist calls either no cancer or likely cancer based on the score. The pathologist carefully reviews your biopsy specimen under a microscope and determines how normal or abnormal the cell structure looks in each sample. The Gleason scores your tissue, one through five, based on lower grade numbers for normal-looking tissue and five for very abnormal tissue. You can see how various grades of the scoring system appear here.

The first number in the score represents the most common cellular structure the pathologist sees, while the second number represents the second most prevalent or common structure. Together, the scores add up to your Gleason and appear such as 3+3 or 3+4. Recently, the Gleason score has been reinterpreted with other findings or biomarkers such as the PSA, how many tumors you have and the location of tumors in or outside the prostate. This allows the urologist and the pathologists to consider factors that may influence how your PCa is diagnosed and explained to you. You can appreciate how complex the diagnosis of PCa becomes with the many ingredients in the mix of your diagnosis. We are fortunate to have this extra complexity rather than when, as in the not-too-distant past, diagnosis was based mostly on the PSA test that led to unnecessary treatments. No more shots in the dark!

There are a few notes to keep in mind about the Gleason. First, it is a partially subjective to interpretation by a pathologist that might be scored differently by another pathologist (also known as a “second opinion”). Second, the scoring is based only on the tissue presented, so missed prostate tissue not biopsied may be better or worse than your samples. Finally, based on the types of biopsy procedure and imaging used (MRI, ultrasound, micro-ultrasound, etc.) your Gleason score is only one point in time based on many factors that influence the score, such as the reader/pathologist, location of the tissue taken in the prostate and quality of the tissue drawn when it reaches the lab. Therefore, most men have more than one biopsy, and based on how many biopsies, may have changing Gleason scores over the years.

Multiple biopsies usually have similar scores if the cancer is not aggressive or indolent, such as with the 3+3 score. It is best to consider this information only as a guide and rely on your urologist and pathologist for a final interpretation. Again, your relationship and mutual decisions are a critical part of your medical care. Gleason scoring or grading is very complex. It is hoped that continued biotechnology advances in imaging, software, and clinician training will improve the accuracy of tissue scoring and improve mapping of the biopsy procedure. Practice makes better.

Prostate cancer prognosis and treatment

Once you and your urologist decide your Gleason score is accurate, the doctor will take into consideration your other health test results, lifestyle and any known family history of disease such as cancers. This determines your “prognosis,” or how you will live with or need treatment for PCa. Alternatives to treatment are active surveillance (AS), including a second or “confirmatory biopsy” and rebiopsies over time, repeat MRIs with or without biopsy, or even new technologies such as the micro-ultrasound and other imaging innovations now in the pipeline. In a future blog post we will review newer alternatives to AS and radiation or surgical treatment, such as partial ablation, extended AS for 3+4 diagnosed men and partial treatment with radiation. Some urologists worldwide are calling for the low grade, low risk 3+3 Gleason score to be dropped as a “cancer” altogether. While a change this drastic seems extreme, rigorous review and debate in the urological community will occur before any major diagnostic terms are changed. That is what I love about science – the rigor!

In summary, the Gleason is one of many biomarkers your medical team will consider when creating a care plan for your diagnosis of PCa. While some high Gleason scores will seem alarming (4s, 5s), there is always time to meet and discuss with your doctor, consider a second opinion and other risk-based tests such as the proven Myriad Prolaris® and other genomic and genetic tests such as the Myriad MyRisk™ hereditary cancer testing. The key to remember is: You are in the pilot seat of your care. Read up before you take off! Know that ongoing research and development of more accurate and reliable prostate testing is underway at Myriad for your peace of mind.

Until we meet again, stay well, eat well and exercise. Fiat Lux!

Looking for more information like this? Read Understanding PSA. Or request a patient guide to learn more about the Prolaris Prostate Cancer Prognostic Test.

Geoff is dedicated to helping families and friends support a prostate cancer patient. He joined the board of Active Surveillance Patients International (ASPI) in 2018 and is an 11-year PCa patient. As a PCa patient advocate, he envisions providing a broad understanding of how patients can collaborate with clinicians for realistic medical care. He enjoys meeting and learning from his clinicians, cancer researchers, providing free online programs for patients, and reminds us that “to live, learn and thrive with PCa” is the motto of ASPI. He is glad he took science courses for understanding a healthy lifestyle that includes exercise and diet.

Geoff also volunteers as a board member and past chairman of the Placer County Mental Health Advisory Board where his interest includes therapy and resources for AS men, and a broad oversight of community mental health programs and innovations. He is married to Constance McLennan, a fine artist, has a grown son, and lives in Northern California.