Grading and staging tell the progress of cancer and whether it has spread:
The Gleason Scale
If prostate cancer is found, the pathologist gives it a grade. The grade is a measure of how quickly the tumor is likely to grow and spread. The most common grading system is called the Gleason score. These scores range from 2 to 10. To determine the grade of a tumor, the pathologist scores each bit of tissue from the biopsy and then adds the two most common values together to determine the Gleason score. Although a score of 2 to 4 shows low aggressiveness, these numbers are almost never seen following a biopsy. The lowest score that is usually found is 5; as a result, that is the least aggressive score. A Gleason score of 6 is more aggressive. Gleason 7 tumors show even higher aggressiveness. These scores come in two varieties. A 4+3 tumor is more aggressive than a 3+4 tumor because more of the higher aggressive grade tumor was found. Gleason 8, 9 and 10 tumors are the most aggressive. These usually have already spread by the time they are found.
Talk to your health care provider about your Gleason score.
Tumor stage shows the size and spread of the cancer. As with other tumors, cancer that involves only a small part of the prostate has a better chance of being treatable than cancer that has spread all through the gland. Likewise, tumors found only in the prostate are more successfully treated than those that have spread outside the prostate (metastasized). Finally, tumors that have spread to places far from the prostate such as to the lymph nodes or bone have the poorest results. The system used for tumor staging is the TNM system, which stands for Tumor, Nodes and Metastasis.
Using the "T" part of the system, localized prostate cancer is staged as:
- T1: Health care provider cannot feel the tumor
- T1a: Cancer present in less than 5% of the tissue removed and low grade (Gleason < 6)
- T1b: Cancer present in more than 5% of the tissue removed or is of a higher grade (Gleason > 6)
- T1c: Cancer found by needle. Biopsy done because of a high PSA
- T2: Health care provider can feel the tumor with a DRE but the tumor is confined to prostate
- T2a: Cancer found in one half or less of one side (left or right) of the prostate
- T2b: Cancer found in more than half of one side (left or right) of the prostate
- T2c: Cancer found in both sides of the prostate
- T3: Cancer has begun to spread outside the prostate and may involve the seminal vesicles
- T3a: Cancer extends outside the prostate but not to the seminal vesicles
- T3b: Cancer has spread to the seminal vesicles
- T4: Cancer has spread to nearby organs such as the urethral sphincter, rectum, bladder, or pelvis wall.
- N0 stage, there is no sign of the cancer moving to the lymph nodes in the area of the prostate
- M0 stage, there is no sign of tumor metastasis
- If the cancer is spreading to the lymph node or if the tumor has spread to other parts of the body, the stage is changed to either N1, for node, and/or M1, for metastasis.
Prostate Cancer Stage Groupings
The T stage is found by DRE and other tests such as ultrasound scan, CT scan, MRI scan, or MR spectroscopy scan. These tests may help find if the cancer is still just in the prostate or has spread. The health care provider may order a CT or MRI scan of the pelvis. This will tell if cancer has spread to the lymph nodes or bones. Sometimes follow-up images are needed to evaluate abnormalities found on the bone scan. These tests are not for men with a Gleason grade lower than 7 and a PSA lower than 10. They rarely show disease.
Prostate cancer usually spreads from the prostate into nearby tissues. Then it spreads to the seminal vesicles, the lymph nodes, the bones, lungs, and other organs. Your health care provider may recommend a pelvic CT scan, an MRI scan or a bone scan to check if your cancer has spread.
Not all men with prostate cancer need to have imaging tests. PSA levels and cancer grade can estimate the risk of spread. A bone scan is not used for:
- Newly diagnosed untreated prostate cancer
- Patients with no symptoms from their cancer
- Gleason score of less than 7 with PSA less than 10 ng/ml (lower grade cancers)
- PSA less than 15 ng/ml, unless the Gleason score is 7 or higher
What Are The Survival Rates For Prostate Cancer?
Due to better screening, 5–year survival is up and death rates are down. Today, 99% of men with prostate cancer live at least 5 years. Most prostate cancers are slow growing. They take many years to progress and cause death. An older man with a tumor is at lower risk of problems in his lifetime than a younger man. Many men with prostate cancer will die from other causes.
But only 29% survive 5 years if their cancer is diagnosed after it has spread to other parts of the body.