After the level of aggressiveness of your prostate cancer is estimated (see Gleason Score), the next step, called staging, estimates if or how far the cancer has spread. The older ABCD system of staging prostate tumors has largely been replaced by the TNM (Tumor, Nodes, Metastases) system, which gauges the severity of cancer on an escalating scale.

  • T stands for tumor and signifies the extent of the cancer in — and adjacent to — the prostate gland.
  • N stands for nodes (lymph nodes) and signifies whether the cancer has — or has not — spread to nearby lymph nodes.
  • M stands for metastasis, the medical term for cancer that has spread to other tissues or organs, such as the bone or the lungs.
  • These three letters are followed by a number and perhaps another letter in small type. The numbers range from 0 to 4 and represent the extent of the tumor. The small letters go from a to c and indicate some subtype of information, as described on the chart below.

    Stage T1

    Tumor is microscopic and confined to prostate but is undetectable by a digital rectal exam (DRE) or by ultrasound. Usually discovered by PSA tests or biopsies.

    Stage T2

    Tumor is confined to prostate and can be detected by DRE or ultrasound.

    Stage T3 or T4

    In stage T3, the cancer has spread to tissue adjacent to the prostate or to the seminal vesicles. Stage T4 tumors have spread to organs near the prostate, such as the bladder.

    Stage N+ or M+
    To each of the TNM stages above may be added an N,M, or G.

    Cancer has spread to pelvic lymph nodes (N+) or to lymph nodes, organs, or bones distant from the prostate (M+).
    The N is for lymph nodes. NX means that the lymph nodes cannot be assessed.
    N0 means the lymph nodes are not involved.
    N1 is a single lymph node, 2 cm or less.
    N2 means metastasis in a single lymph node greater than 2 cm or multiple lymph nodes with sum greater than 2 cm.
    N3 indicates lymph with greater than 5 cm metastasis.

    M is for metastasis.
    MX means that distant metastasis cannot be assessed.
    MO means no distant metastasis,
    M1a is nonregional lymph nodes,
    M1b is bone metastasis,
    M1c is other sites.

    Primary tumor (T)

    TX Tumor cannot be assessed
    T0 No evidence of primary tumor
    T1 Clinically not palpable or visible by imaging
    T1a Found incidental to other surgery; present in 5% or less of tissue
    T1b Found incidental to other surgery; present in 5% or more of tissue
    T1c Identified by needle biopsy
    T2 Tumor confined within prostate
    T2a Involving half a lobe or less of prostate
    T2b Involving half a lobe
    T2c Involving both lobes
    T3 Tumor extends through prostate capsule
    T3a Extends through one lobe
    T3b Extends through both lobes
    T3c Extends into seminal vesicles
    T4 Involves structures other than seminal vesicles
    T4a Invades bladder neck, external sphincter, or rectum
    T4b Invades muscles and/or pelvic wall

    Regional Lymph Nodes (N)

    NX Nodes cannot be assessed
    N0 No regional node metastasis
    N1 Single node metastasis, 2 centimeters (cm) or less at largest point
    N2 Single node metastasis, 2 cm to 5 cm at largest point, or multiple nodes, no larger than 5 cm at largest point
    N3 Metastasis larger than 5 cm in any node

    Distant Metastasis (M)

    MX Metastasis cannot be assessed
    M0 No distant metastasis
    M1 Distant metastasis
    M1a Distant lymph node(s) involved
    M1b Bone(s) involved
    M1c Other site(s) involved