Prostate cancer: How do doctors estimate how it will progress?
Whether and how prostate cancer continues to grow will vary from person to person: Some tumors are small and grow either slowly or not at all. Others are large and grow rapidly. Various examinations can be used to predict which group the cancer is in.
When choosing a treatment, it's important to know how the cancer will probably progress. The treatment options that are considered depend on
- how big the tumor is (stage), and
- the likelihood that it will grow (risk of progression).
Various examinations can be used to determine the tumor stage and risk of progression. They include the following:
- Feeling the prostate (palpation)
- Imaging techniques (ultrasound and MRI)
- A blood test to determine the prostate-specific antigen level (PSA level)
- Tissue sample ("punch" biopsy)
If the cancer is at an advanced stage, further imaging techniques (e.g. computed tomography, or CT) can be used in order to see whether it has led to tumors (metastases) in other parts of the body. The following information is about localized prostate cancer. That means that the cancer has not spread to the lymph nodes and has not yet led to any metastases.
How is the tumor stage determined?
The tumor stage describes how big the tumor is and whether it has already spread. It is notated based on a system called the TNM classification:
- T describes how much the tumor has spread
- N shows whether the lymph nodes are affected
- M indicates whether metastases have formed
The following table shows the tumor stages.
|Original tumor (primary tumor)||
No tumor can be found using palpation (feeling with a finger) or ultrasound exams
Found by chance, less than 5% of the tissue contains cancer cells
Found by chance, more than 5% of the tissue contains cancer cells
After high PSA levels were measured, cancer cells were found in tissue samples (a biopsy)
The tumor can be felt with a finger or seen in an ultrasound, but has not yet spread to other parts of the body
The tumor is in less than one half of only one side (left or right) of the prostate
The tumor is in more than half of one side (left or right) of the prostate
The tumor is in both sides of the prostate
The tumor has spread outside the prostate into the connective tissue around the prostate or the seminal vesicles
The tumor has spread further, to nearby organs such as the bladder or bowel
There are no tumors in nearby lymph nodes
Nearby lymph nodes have cancer in them
No metastatic tumors were found
Metastatic tumors were found
Localized prostate cancer includes tumors in categories T1 and T2 that have not spread to the lymph nodes (N0) and have not formed metastases (M0). So, for instance, T2a N0 M0 would be one possible TNM classification for a particular case of localized prostate cancer.
How is the risk of progression determined?
Localized prostate cancer tumors are divided into various risk groups (risk of progression) according to whether and how they are likely to progress. The following information is needed in order to determine the risk of progression:
- The exact tumor stage (TNM)
- The PSA levels
- The Gleason score
The Gleason score is determined based on what the tissue samples look like under the microscope. It describes how much the prostate cells have changed. The lowest score for prostate cancer is 6 and the highest is 10. Tumors with a lower score grow more slowly than tumors with a higher score. To determine the Gleason score, the two tissue samples with cells that have changed the most are given a Gleason grade describing how aggressive the tumor cells are. Those two grades are then added together. For instance, if the first sample has a Gleason grade of 4 and the second sample has a Gleason grade of 3, the Gleason score is 7.
The cancer is assigned to one of four groups, based on the tumor stage, the PSA level and the Gleason score:
- Very low risk
- Low risk
- Intermediate risk
- High risk
Very low-risk prostate cancer and low-risk prostate cancer are often grouped together and described as "low-risk" prostate cancer.
The following table shows the criteria used for the four risk groups and the usual treatment options for each group:
|Very low risk||
At least one of these criteria applies:
At least one of these criteria applies:
Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften (AWMF), Deutsche Krebsgesellschaft (DKG), Deutsche Krebshilfe (DKH). Interdisziplinäre Leitlinie der Qualität S3 zur Früherkennung, Diagnose und Therapie der verschiedenen Stadien des Prostatakarzinoms. AWMF-Registernr.: 043-022OL. May 2019.
Donovan JL, Hamdy FC, Lane JA, Mason M, Metcalfe C, Walsh E et al. Patient-reported outcomes after monitoring, surgery, or radiotherapy for prostate cancer. N Engl J Med 2016; 375(15): 1425-1437.
Hamdy FC, Donovan JL, Lane JA, Mason M, Metcalfe C, Holding P et al. 10-year outcomes after monitoring, surgery, or radiotherapy for localized prostate cancer. N Engl J Med 2016; 375(15): 1415-1424.
Robert Koch-Institut (RKI), Gesellschaft der epidemiologischen Krebsregister in Deutschland (GEKID). Krebs in Deutschland für 2015/2016. Berlin: RKI; 2019.
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