Prostate Cancer: Grading
Your healthcare team must learn more about your cancer in order to make the best treatment plan. What do the cancer cells look like? Has the cancer spread beyond your prostate? How fast do the cells appear to be growing? Are they likely going to spread quickly?
Cells taken out during your prostate biopsy are sent to a lab. There, the cells are tested and a pathologist looks at them with a microscope. A pathologist is a healthcare provider who identifies diseases by studying cells and tissues. They then figure out the cancer’s grade. The pathologist will send a report to your urologist.
Your treatment options will depend on how the cells look (called the grade) and where they are in your body (the stage).
Grading the cancer
Often there is more than 1 grade within a tumor. The 2 biggest parts of cancer in the biopsy tissue are each given a grade. A scale of 1 to 5 is used. Low-grade cancers (grade 1) look a lot like normal tissue. High-grade cancers (grade 5) differ from normal tissue in the way cells are grouped, and in cell size and shape. The higher the grade, the faster the cancer is likely to be growing. Almost all prostate cancers are grade 3 or higher.
Grade 1 or 2
The cancer cells are abnormal, but are still organized in rings like healthy prostate cells. Your doctor may call the cells well differentiated.
This may mean a slow-growing cancer.
Grades 1 and 2 are very rarely used.
Grade 3 cancer cells vary more in size and shape. Fewer rings can be seen.
These cancer cells may grow faster or still be slow growing.
Grade 4 or 5
These cancer cells form irregular, closely packed rings or don’t form rings at all. They vary even more in size and shape than lower-grade cells. They may be called poorly differentiated.
These grades mean a fast-growing cancer.
The Gleason score
The 2 most common grades found in the tumor are added together to get the Gleason score (or Gleason sum). This score helps your urologist figure out the best treatment for your prostate cancer.
The first number used tells you which grade is most common in the biopsy tissue. So, if your score is 4 + 3 = 7, most of the tumor was grade 4, but some grade 3 was also seen.
Gleason scores can be between 2 and 10, but nearly all prostate can cancers have a score of 6 or higher. Gleason scores are used to put prostate cancers into 3 groups:
Gleason score 6 or less
Gleason score 7
Gleason score 8 to 10
These cancers are well-differentiated. The cells look a lot like normal cells. They're also low-grade. They tend to be slow growing.
These fall right in the middle. They're moderately differentiated and intermediate grade.
These cancer cells look very different from healthy cells and are growing quickly. They may be called poorly differentiated and high-grade.
Health experts have recently found that prostate cancer grade can be even better used to divide people into groups to help predict how well they're going to do. These are called grade groups. They range from 1 to 5. Group 1 cancers are slow to grow and spread. Group 5 cancers grow and spread faster. People in the lower grade groups tend to do better than those in higher grade groups.
Grade groups are based on Gleason scores:
Grade group 1 is a Gleason score 6 or less.
Grade group 2 is a Gleason score of 3 + 4 = 7.
Grade group 3 is a Gleason score of 4 + 3 = 7.
Grade group 4 is a Gleason score of 8.
Grade group 5 is a Gleason score of 9 or 10.
Grade and stage
Your grade group and your PSA level are key pieces of information used to determine your cancer stage. This process is complex. Ask your provider to explain how it works, what it means, how it impacts your treatment options, and what it might tell you about your long-term outcomes.