TNM Staging System
The TNM (tumor, nodes, metastasis) staging system is used to describe prostate cancer's clinical stage, or how far it has spread. The system assigns a T number (T1 to T4) to describe the extent of the tumor as felt during a digital rectal exam (DRE). The N number (N0 to N1) indicates whether the cancer has spread to any lymph nodes, and the M number (M0 to M1) indicates the presence or absence of metastasis (spread to distant sites).
The T and M designations are divided into subcategories (designated a, b and c) that provide further detail on the extent of the cancer. The TNM staging system is used to help determine appropriate prostate cancer treatment options.
Primary tumor (T)
| TX | Tumor cannot be assessed |
| T0 | No evidence of primary tumor |
| T1 | Tumor cannot be felt during DRE or seen with diagnostic imaging
|
| T1a | Tumor found incidentally during surgery for benign prostatic hyperplasia (BPH) and is present in less than 5% of removed tissue |
| T1b | Tumor found incidentally during BPH surgery but involves more than 5% of removed tissue |
| T1c | Tumor found during needle biopsy for elevated PSA |
| T2 | Tumor can be felt during DRE but is believed to be confined to the gland |
| T2a | Tumor involves one half or less of one side of the prostate |
| T2b | Tumor involves more than one half of one side but not both sides |
| T2c | Tumor involves both sides of the prostate |
| T3 | Tumor extends through the prostate capsule and may involve the seminal vesicles |
| T3a | Tumor extends through the capsule but does not involve the seminal vesicles |
| T3b | Tumor has spread to the seminal vesicles |
| T4 | Tumor has invaded adjacent structures (other than the seminal vesicles), such as the bladder neck, rectum or pelvic wall |
Regional Lymph Nodes (N)
| NX | Nodes cannot be assessed |
| N0 | Cancer has not spread to any lymph nodes |
| N1 | Cancer has spread to one or more regional lymph nodes (nodes in the pelvic region) |
Distant Metastasis (M)
| MX | Metastasis cannot be assessed |
| M0 | No distant metastasis |
| M1 | Distant metastasis |
| M1a | Cancer has spread to distant lymph nodes |
| M1b | Cancer has spread to the bones |
| M1c | Cancer has spread to other organs, with or without bone involvement |
