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Staging and Grading

Once prostate cancer is confirmed by a biopsy, it’s important to learn the stage (location) and grade (aggressiveness) of the tumor.

What is Staging?

Staging is the process used to find out if the cancer has spread within the prostate or to other parts of the body, using biopsy and imaging. More detailed information on staging is available at the bottom of this page.

  • Stage I: the cancer is small and only in the prostate
  • Stage II: the cancer is larger and may be in both lobes of the prostate but is still confined to the prostate
  • Stage III: the cancer has spread beyond the prostate to nearby lymph glands or seminal vesicles
  • Stage IV: the cancer has spread to other organs such as the bone and is referred to as metastatic cancer.

Stages-PCa-table

What is Grading?

The grade is also called the Gleason score. This score can indicate how quickly the tumor will grow and spread.

To find a Gleason score, the tumor cells from the biopsy are looked at under a microscope. A number is assigned to them based on how abnormal they appear. The scale goes from 1 (non-aggressive) to 5 (very aggressive). The numbers of the two most common patterns are added together to create a Gleason Score.

For example, in a biopsy where the most common cell type is a 3, and the second most common cell type is a 4, would be a Gleason Score 7. However, a biopsy where the most common cell type is a 4 and the second most common cell type is a 3 would also be considered a Gleason Score 7. Keep in mind, though, that a 3+4 can progress very differently than a 4+31. Today almost all patients have a Gleason Score of 6 or above.

  • Gleason 6: the tumor tissue is well differentiated, less aggressive, and likely to grow more slowly
  • Gleason 7: the tumor tissue is moderately differentiated, moderately aggressive, and likely to grow but may not spread quickly
  • Gleason 8-10: the tumor tissue is poorly differentiated or undifferentiated, high aggressive, and likely to grow faster and spread

Gleason-Scores-table

What does staging and grading mean for treatment?

These two numbers are the most important for determining your future course of treatment. Some treatments are only effective for Stages I and II, where the cancer is still confined to the prostate. Some other treatments only become necessary at Stages III and IV, where the cancer has spread outside the prostate.

Grading is especially useful in early-stage disease. If the tumor shows signs of being aggressive, it may make sense to go forward with treatment. If the tumor does not seem aggressive, it may make sense to go forward with active surveillance and avoid side effects.

In any case, the stage and grade should be a vital component of any discussion with your doctor.

More detail on staging —

The standardized Tumor, Node, and Metastasis (TNM) system is used to stage prostate cancer. The T category is based on the extent of the tumor itself. The N category is based on whether the cancer has spread to nearby lymph nodes. The M category is based on whether the cancer has spread beyond nearby lymph nodes.

T (Tumor) Categories:

  • T1: the tumor cannot be felt with a DRE or seen with imaging
    • T1a: the tumor is found accidentally during a surgery for benign prostatic hyperplasia or another prostate condition. The tumor takes up less than 5% of the removed tissue
    • T1b: the tumor is found accidentally during a surgery, and the tumor takes up more than 5% of the removed tissue
    • T1c: the tumor is diagnosed with a needle biopsy, usually because of an elevated PSA
  • T2: the tumor is confined to the prostate and can be either felt with a DRE or seen with imaging
    • T2a: the tumor is confined to half of one lobe of the prostate
    • T2b: the tumor is present to more than half of one lobe, but is not in both lobes
    • T2c: the tumor is present in both lobes of the prostate
  • T3: the tumor has grown outside of the prostate and may be present in the seminal vesicles
    • T3a: the tumor is outside of the prostate, but is not in the seminal vesicles
    • T3b: the cancer is outside of the prostate and has spread to the seminal vesicles
  • T4: the tumor has grown into tissues beyond the seminal vesicles

N (Node) Categories:

  • NX: nearby lymph nodes were not checked for cancer
  • N0: the tumor is not present in nearby lymph nodes
  • N1: the tumor has spread to one or more nearby lymph nodes

M (Metastasis) Categories:

  • M0: the cancer is not present in other parts of the body beyond the nearby lymph nodes
  • M1: the cancer is present in the body beyond the nearby lymph nodes
    • M1a: the cancer has spread to distant lymph nodes
    • M1b: the cancer has spread to the bones
    • M1c: the cancer has spread to other organs

Each of the stages is based on some combination of these categories.

Stage 1:

  • The tumor cannot be felt with a DRE or seen with imaging (T1), and the PSA is less than 10 ng/mL, with a Gleason score of 6 or lower; OR
  • The tumor can be felt with a DRE or seen with imaging, but is confined to half of one lobe (T2a), and the PSA is less than 10 ng/mL, with a Gleason score of 6 or lower; OR
  • The tumor is either in T1 or T2a, but the PSA and Gleason score are unknown

Stage 2A:

  • The tumor cannot be felt with a DRE or seen with imaging (T1), or the tumor is confined to half of one lobe (T2a), and the PSA is less than 20 ng/mL, with a Gleason score of 7; OR
  • The tumor is either in T1 or T2a, and the PSA is equal or more than 10 ng/mL but less than 20 ng/mL, with a Gleason of 6 or lower; OR
  • The tumor is present to more than half of one lobe, but is not in both lobes (T2b), and the PSA is less than 20 ng/mL, with a Gleason score of 7 or lower; OR
  • The tumor is present to more than half of one lobe, but is not in both lobes (T2b), and the PSA and Gleason score are unknown

Stage 2B:

  • The tumor is present in both lobes of the prostate (T2c), with any PSA and any Gleason score; OR
  • The tumor is either in T1 or T2, and the PSA is equal or less to 20 ng/mL, with any Gleason score; OR
  • The tumor is either in T1 or T2, with any PSA and a Gleason of 8 or higher

Stage 3:

  • The tumor has grown outside of the prostate and may be present in the seminal vesicles (T3), with any PSA and any Gleason score

Stage 4:

  • The tumor has grown into tissues beyond the seminal vesicles, with any PSA and any Gleason score, OR
  • The tumor has spread to one or more nearby lymph nodes, without metastases, with any PSA and any Gleason score; OR
  • The cancer is present in the body beyond the nearby lymph nodes, in tissues like the bone or distant organs, with any PSA and any Gleason score

What are the D’Amico risk categories?

The D’Amico system provides an estimate of the risk of recurrence at five years after treatment. This system is one of the most widely used for risk assessment. It combines the PSA, Gleason score, and the clinical stage to create low, intermediate, and high risk categories. The higher the risk category, the higher the chance of recurrence is five years after treatment.

The D’Amico risk categories are below. If one factor is putting you in a lower category but another is putting you in a higher category, then the higher category takes precedent.

Low Risk:

  • PSA is less than 10 ng/mL AND
  • Gleason score is equal to or less than 6 AND
  • Clinical stage T1-T2a

Intermediate Risk:

  • PSA is between 10 and 20 ng/mL OR
  • Gleason score is 7 OR
  • Clinical stage T2b

High Risk:

  • Gleason score is 8-10 OR
  • PSA is greater than 20 ng/mL OR
  • Clinical stage T2c-T3

 

[1] http://urotoday.com/2014-09-18-02-47-34/prostate-cancer/82455-a-contemporary-prostate-cancer-grading-system-a-validated-alternative-to-the-gleason-score.html