The TNM System describes the extent of the primary tumor (T stage), whether the cancer has spread to nearby lymph nodes (N stage), and the absence or presence of distant metastasis (M stage). The TNM System has been accepted by the International Union Against Cancer (UICC) and the American Joint Committee on Cancer (AJCC). The stages described below are based on the most recent version of the AJCC staging manual.
The clinical stage is based on your tests before surgery, such as your PSA results and your doctor's assessment of your cancer from the DRE. If you have surgery, your doctors can determine the pathologic stage, based on the surgery and examination of the removed tissue. There are four categories for describing the prostate tumor's (T) stage, ranging from T1 to T4.
Stage Explanation
| T1 | Your doctor can't feel the tumor or see it with imaging such as transrectal ultrasound. |
| T1a | The cancer is found incidentally during a transurethral resection (often abbreviated as TURP) for benign prostatic enlargement. Cancer is present in less than 5 percent of the tissue removed. |
| T1b | The cancer is found after TURP but is present in more than 5 percent of the tissue removed. |
| T1c | The cancer is found by needle biopsy that was done because of an elevated PSA. |
| T2 | Your doctor can feel the cancer when a digital rectal exam (DRE) is done, but it still appears to be confined to the prostate gland. |
| T2a | The cancer is in one half or less of only one side (left or right) of your prostate. |
| T2b | The cancer is in more than half of only one side (left or right) of your prostate. |
| T2c | The cancer is in both sides of your prostate. |
| T3 | The cancer has begun to spread outside your prostate and may involve the seminal vesicles. |
| T3a | The cancer extends outside the prostate but not to the seminal vesicles. |
| T3b | The cancer has spread to the seminal vesicles. |
| T4 | The cancer has spread to tissues next to your prostate (other than the seminal vesicles), such as your bladder's sphincter (muscles that help control urination), your rectum, and/or the wall of your pelvis. |
| Stage I In Stage I, cancer is found in the prostate only. It cannot be felt during a digital rectal exam (DRE) and is not visible by imaging. It is usually found accidentally during surgery for other reasons, such as benign prostatic hyperplasia. Stage I prostate cancer may also be called stage A1 prostate cancer. | 
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Stage II In Stage II, cancer is more advanced than in Stage I, but has not spread outside the prostate. Stage II prostate cancer may also be called Stage A2, Stage B1, or Stage B2 prostate cancer. | 
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| Stage III In Stage III, cancer has spread beyond the outer layer of the prostate to nearby tissues. Cancer may be found in the seminal vesicles. Stage III prostate cancer may also be called Stage C prostate cancer. | 
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| Stage IV In Stage IV, cancer has metastasized (spread) to lymph nodes near or far from the prostate or to other parts of the body, such as the bladder, rectum, bones, liver, or lungs. Metastatic prostate cancer often spreads to the bones. Stage IV prostate cancer may also be called Stage D1 or Stage D2 prostate cancer. | 
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