What Is a Gleason Score for Prostate Cancer?

What Is a Gleason Score?

One of the main metrics for evaluating cancer is its grade. This number describes how cancer cells appear under a microscope, including how different they look from normal, healthy cells. Determining cancer grade enables oncologists to predict how quickly the cancer is likely to grow.

Traditionally, prostate cancer grades are based on the Gleason grading system. This system is named after Dr. Donald Gleason, a pathologist who developed the scoring system in the 1960s. Dr. Gleason discovered that prostate cancer cells fall into five distinct patterns as they evolve. These patterns help pathologists determine exactly how much the cancer cells have mutated, allowing a more precise understanding of a tumor and its development.

The Gleason score is determined by examining tissue obtained from a biopsy. During this procedure, the physician uses a hollow needle to take a small sample of tissue from the tumor. This sample is then evaluated in a laboratory to confirm the presence of cancer and learn more about its characteristics. The Gleason score is included in the final pathology report, along with other vital information.

Understanding the Gleason Grading System

Pathologists calculate Gleason scores by studying tissue samples under a microscope. They grade each sample on a 1-to-5 scale based on how abnormal it appears when compared to normal cells. The higher the grade, the more abnormal the cells in the sample look:

• Grade 1: Cancerous cells look like normal cells.
• Grades 2-4: The cancerous cells look somewhat abnormal.
• Grade 5: The cancerous cells look very abnormal.

Cancer spreads outward, with newly affected cells gradually becoming more abnormal over time. This can create multiple areas of prostate cancer with different grades. Pathologists select the two largest cancerous areas, adding each area’s grade together to determine an overall Gleason score, also called a Gleason sum. For example, if the largest cancerous area is Grade 2 and the next largest is Grade 5, the Gleason sum is 7. Sums are divided into three groups:

• Low grade: This includes grade 6 cancer and may be called well differentiated. Cancerous cells mostly look like healthy cells.
• Intermediate grade: This includes grade 7 cancer and may be called moderately differentiated. Cancerous cells look only somewhat like healthy cells.
• High grade: This includes grade 8, 9, and 10 cancers and may be called poorly differentiated or undifferentiated. Cancerous cells look quite different from healthy cells.

The final biopsy report will include the overall grade, as well as whether any cells at Gleason grade 5 are present. Even a small amount of grade 5 cells can put a patient at higher risk for recurrence, making this important information for treatment planning.

Understanding Prostate Cancer Grade Groups

Though the Gleason scoring system is largely effective, it has a few problems. The first is that the lowest score pathologists will assign is a 6. Because Gleason scores can range from 2 to 10, grade 6 may sound more serious than it is. This can cause unnecessary stress for the patient.

Another issue is that the three groups described above are fairly broad, which limits their usefulness to some extent. For example, a man with a Gleason score of 3+4 = 7 and one with a score of 5+2 = 7 both have intermediate-grade cancer. The first, however, has fewer highly abnormal cells and likely will respond better to treatment than the man who has Grade 5 cancerous cells. Similarly, men with a Gleason score of 8 generally will fare better than those with scores of 9 or 10, even though all three are considered to have high-grade prostate cancer.

To address these issues, pathologists have modified the system into grade groups. These range from grade 1 (most likely to spread slowly) to 5 (most likely to spread quickly):

• Grade Group 1: Gleason 6
• Grade Group 2: Gleason 3+4 = 7
• Grade Group 3: Gleason 4+3 = 7
• Grade Group 4: Gleason 8
• Grade Group 5: Gleason 9 and 10

Eventually, the Grade Group system may replace the Gleason system. Currently, however, the systems are included side-by-side on most biopsy reports.

How Important Is the Gleason Grade?

The grade of prostate cancer, whether recorded as a Gleason score or grade group, is an especially important factor when it comes to predicting the cancer’s behavior and planning treatment. It’s not the only factor to consider, however. Biopsy reports contain other information that is also useful for planning prostate cancer treatment, including:

• How many of the total number of samples taken contain cancer
• What proportion of each sample is composed of cancer
• Whether cancer was found on the right side, left side, or both sides of the prostate
• Whether cancer cells contain receptors for male hormones, or androgens
• Imaging test findings, especially if cancer has spread outside the prostate
• The patient’s personal and family medical history, and his age and overall health, including any other medical conditions he may have

This information provides a more complete understanding of the patient’s prostate cancer and of his likely response to various treatment options.

Treatment Options for Prostate Cancer

Once biopsy testing and other assessments are completed and final reports for those evaluations are provided, the patient and his cancer care team can begin planning treatment. Options include:

Watchful Waiting

In the early stages of prostate cancer, the tumor generally grows very slowly. Treatment may not be an urgent concern. Medical oncologists often simply monitor low-grade cancers, especially in low-risk or elderly patients. If the tumor shows signs of worsening, treatment may begin.

Active Surveillance

Like watchful waiting, active surveillance entails not immediately initiating treatment. However, as its name implies, this option involves a more proactive approach to monitoring the patients, such as with regularly scheduled biopsies and imaging studies.

Cryotherapy

Cryotherapy is a treatment option for very early-stage, low-grade prostate cancers. During this procedure, doctors inject extremely cold gases into the body. These freeze and kill cancer cells, eliminating the tumor without requiring surgical removal.

Radical Prostatectomy

Radical prostatectomy is the primary surgical procedure used to treat prostate cancer. It involves removing the entire prostate and surrounding tissues. It is often effective, especially if cancer has not spread outside the prostate. However, it may result in bladder control problems or erectile dysfunction.

Radiation Therapy

Radiation therapy uses high-energy rays or particles to kill prostate cancer cells with no or minimal damage to nearby healthy tissue. The radiation may be delivered by means of a beam directed at the body from a machine called a linear accelerator or through a closed source that is placed in the body at or immediately adjacent to the site of the cancer. In some cases, radiation-delivering drugs knowns as radiopharmaceuticals are infused intravenously and then target and attack cancer cells.

Chemotherapy

For high-grade, later-stage prostate cancer, chemotherapy may be used. This treatment uses strong drugs that circulate through the entire body to eliminate cancer cells at their source, and anywhere they may have spread. It may also be used to shrink a tumor before other treatments are provided.

Hormone Therapy

Prostate cancer often relies on male hormones called androgens to grow. Hormone therapy can reduce levels of androgens or interfere with their ability to help prostate cancer cells survive and spread.

Immunotherapy

Immunotherapy harnesses the body’s own immune system to identify and attack cancer cells. Different forms of immunotherapy are employed in prostate cancer treatment, although their use is generally reserved for later-stage cancer.

Receive Prostate Cancer Treatment at an RCCA Location Near You

Regional Cancer Care Associates offers prostate cancer treatment at more than 20 locations across New Jersey, Connecticut, Massachusetts, Maryland, and the Washington, D.C., area. Our medical oncology team has experience in treating a wide variety of cancers and blood disorders, using targeted treatments where appropriate to ensure the best results. Contact us to learn more about Gleason scores or to request an appointment for treatment today.