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 percent of removed tissue
    • T1b Tumor found incidentally during BPH surgery but involves more than 5 percent 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

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 09 Jun 1998

Last Modified: 01 Oct 2015