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TNM Staging System for Prostate Cancer

What Does Your Prostate Cancer Stage Mean?


Updated June 18, 2014

The staging of prostate cancer is the process by which the cancer’s extent or spread is measured. There is a uniform system for classifying prostate cancer based on its stage.

The most commonly used staging system today is the TNM system. If your doctor has given you a stage for your prostate cancer in this system, it is important to understand what it means.

What Does Your TNM Stage Mean?

The TNM system for describing prostate cancer uses the letters “T,” “N,” and “M” to signify “Tumor,” “Nodes,” and “Metastasis.”

The following is the breakdown of exactly what each category in this system means.

Primary tumor (T)

  • TX: The primary tumor was not or could not be assessed.

  • T0: There is no evidence of a primary tumor.

  • T1: The tumor could not be found by examination or with the use of imaging (like ultrasound or an MRI scan), but was incidentally found during a biopsy or surgery.

    T1a: The tumor is found in 5% or less of the tissue that was taken.

    T1b: The tumor is found in more than 5% of tissue that was taken.

    T1c: The tumor was found by needle biopsy after an elevated PSA level.

  • T2: The tumor is found only within the prostate itself.

    T2a: The tumor is found in 50% or less of one lobe.

    T2b: The tumor is found in more than 50% of one lobe.

    T2c: The tumor is found in both lobes.

  • T3: The tumor has extended through the capsule that surrounds the prostate.

    T3a: The tumor has only gone through the capsule without invading the seminal vesicles.

    T3b: The tumor has invaded the seminal vesicles.

  • T4: The tumor has invaded structures or tissues near the prostate other than the seminal vesicles. These include the bladder neck, the rectum, and the pelvic wall along with other structures.

Nodes (N)

  • NX: The lymph nodes were not or could not be assessed.

  • N0: The nodes do not show evidence of cancer.

  • N1: The nodes show evidence of cancer.

Metastasis (M)

  • MX: The presence of metastases was not or could not be assessed.

  • M0: There is no evidence of distant metastasis.

  • M1: There is evidence of distant metastasis.

    M1a: Cancer has been found in lymph nodes far from the prostate.

    M1b: Cancer has been found in the bone.

    M1c: Cancer has been found in another area of the body.

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