The TNM System of Rating Your Prostate Cancer
The TNM classification system is used internationally to categorize cancer. It was developed by the American Joint Committee on Cancer, in order to universally classify the extent of prostate cancer involvement in patients no matter where they are diagnosed.
Once you find out your TNM classification, you must determine the Cancer Stage to see the recommended treatments for your specific cancer situation.
The "T" Classification
The "T" system describes how extensive the prostate cancer is by how much of the prostate it has invaded. It also describes if the cancer has spread outside of the prostate.
- T0: There are no cancer cells present. A good thing!
- T1: Tumor cannot be felt on palpation and is not visible during an ultrasound.
- T1a, T1b: Found during a transurethral urethral resection of the prostate (TURP) procedure to increase urine flow as tissue examined after being removed is found to contain cancer cells. If less than five percent of the cells are cancerous, it is T1a, if more it is classified as T1b.
- T1c: Found during a biopsy ordered because of elevated PSA levels.
- T2: A Tumor can be felt on palpation during a DRE, but is confined to the prostate gland and not visible during a transrectal ultrasound (TRUS) procedure.
- T2a: Tumor involves half or less of one lobe of the prostate.
- T2b: Tumor involves more than half of one lobe of the prostate
- T2c: Tumor involves both lobes of the prostate.
- T3: A tumor has extended beyond the prostate capsule (the outer boundary of the prostate, but has not spread to other organs.
- T3a: Unilateral extension out of the prostate (in one direction).
- T3b: Multilateral extension out of the prostate (in several directions).
- T3c: Tumor has invaded at least one seminal vesicle.
- T4: A tumor has fixed itself on, or invaded adjacent body structures (other than the seminal vesicles described in T3c.)
- T4a: Tumor has invaded the neck of the bladder, the rectum, or the external sphincter.
- T4b: Tumor has fixed itself to the pelvic wall, or has invaded the levator muscles.
The "N" Number
The "N" system tells a healthcare professional how extensive the prostate cancer tumor has spread to the local (regional) lymph nodes. The "N" numbers vary from zero to three, with a higher number indicating more extensive involvement.
- N0: No lymph node involvement.
- N1: Cancer cells were found in one lymph node, and the tumor is less than 2 cm. in its longest direction.
- N2: Cancer cells were found in one lymph node, and the tumor is between two and five cm. in its longest direction.
- N3: A tumor was found in a regional lymph node that is greater than five cm. in its longest direction.
The "M" Number
The "M" number describes if the prostate cancer has spread to other areas of the body or not. Like the "N" rating, the lower the number, the less involvement.
- M0: No distant metastasis.
- M1a: Cancer cells have been found in lymph nodes distant from the prostate.
- M1b: Cancer cells have spread to the bones. M1b(a) means that the cancer has been found in the axial skeleton only (not the arms or legs). M1b(b) means that the cancer has also been found in the arm or leg bones.
- M1c: Cancer cells have spread to other organs.
