Once your doctor has confirmed the presence of prostate cancer, he or she will need to grade and stage it so a treatment strategy can be put together. Two key steps in cancer diagnosis are:
(1) determining how different the cancer cells are from normal healthy cells (grading); and
(2) determining the degree to which the cancer has spread (staging).
Grading Prostate Cancer – The Gleason Score
After biopsy, cancer cells are graded according to the Gleason Scale.
Grading is an indication of how aggressive a cancer is compared to healthy cells.
All cancer cells are not created equal: some are aggressive and fast-moving, others are lethargic and less likely to spread, and still others are somewhere in between.
To determine how aggressive the cancer is, a pathologist will study the patterns of two slides of cancer cells taken through a biopsy to identify their most common patterns.
Each pattern is given a rating of 1 to 5, with 1 being non-aggressive and 5 being very aggressive.
Gleason Patterns are associated with the following features:
- Pattern 1 – The cancerous prostate closely resembles normal prostate tissue. The glands are small, well-formed, and closely packed.
- Pattern 2 – The tissue still has well-formed glands, but they are larger and have more tissue between them.
- Pattern 3 – The tissue still has recognizable glands, but the cells are darker. At high magnification, some of these cells have left the glands and are beginning to invade the surrounding tissue.
- Pattern 4 – The tissue has few recognizable glands. Many cells are invading the surrounding tissue.
- Pattern 5 – The tissue does not have recognizable glands. There are often just sheets of cells throughout the surrounding tissue.
The scores of each of the most dominant patterns are added together to produce a total score (The Gleason Score) that ranges from 2 – 10.
The lower the score the better. A combined Gleason score of 10 is generally not good.
Here’s a general breakdown of the patterns and scores:
- 2 to 4 are very low on the cancer aggression scale
- 5 to 6 are mildly aggressive
- 7 indicates moderately aggressive cancer
- 8 to 10 indicates highly aggressive cancer
Another grading method to determine the best treatment options is the Partin tables which help doctors predict whether the cancer is limited to the prostate or has metastasized to nearby tissues or lymph nodes. The prediction is based on a patient’s PSA level, Gleason score, and cancer stage.
Staging Prostate Cancer
Diagram showing the four stages of prostate cancer
Determining the “stage” of the cancer shows how far the cancer has spread from the prostate, if at all.
There are four stages of prostate cancer:
Stage I:
The cancer is confined to the prostate, cannot be found through a DRE or scanning, and has a low Gleason score
Stage II:
The cancer is still confined to the prostate, but it is more advanced and has a higher Gleason score.
Stage III:
The cancer has spread beyond the prostate, but only locally.
Stage IV:
The cancer has spread to the lymph nodes, bones, or other sites or organs in the body.
