What is low-risk prostate cancer and how is it treated?
Low-risk prostate cancer often grows very slowly, or doesn't grow at all. Because of this, a treatment approach known as "active surveillance" can be considered as an alternative to radiotherapy or surgery. In this approach, the tumor is monitored regularly and only treated with radiotherapy or surgery if it grows or becomes more aggressive.
The diagnosis "prostate cancer" usually comes as a shock to men and those close to them. The good news is that the chances of recovery are generally good. This is because prostate cancer tumors are typically small and haven't spread yet (are still "localized”) when they are discovered.
There are various treatment options for localized prostate cancer. Each of these treatments has advantages and disadvantages, so it's a good idea to get enough information and discuss the options with your doctors before making a decision. Research results can also help you to choose a treatment that is suitable for you personally.
Please note: The treatment option "active surveillance" described below is only considered in men who have localized prostate cancer that isn't thought to be aggressive. In other words, if doctors are quite sure that the tumor will grow only very slowly, or not at all. "Low-risk prostate cancer" like this is often discovered because men had a screening test and were found to have high PSA levels.
How is the stage of prostate cancer and the risk of progression determined?
In order to assess the likelihood that prostate cancer will get worse (the risk of progression), various tests are done. These include a blood test, a palpation test (feeling the prostate with hands), an ultrasound examination and taking a tissue sample (biopsy). Biopsies involve taking 10 to 12 small samples of tissue from the prostate and looking at them under a microscope.
The stage of cancer is determined based on the results of these tests. Doctors do this using the TNM staging system, where T refers to the tumor size, N describes whether the lymph nodes are affected, and M indicates whether the cancer has spread to other parts of the body (metastasis). If the cancer has progressed, further imaging techniques like computer tomography may be used in order to look for other cancerous growths that have spread from the original prostate tumor (metastases).
But knowing the stage of cancer isn't enough to predict how likely the tumor is to continue growing.
In order to assess the risk of progression, the man's PSA levels and Gleason score are determined.
- PSA levels: The “prostate-specific antigen” level in men's blood is measured using the PSA test. This antigen is a protein that is made in the prostate. Small amounts of PSA enter the bloodstream. Men who have prostate cancer usually have higher PSA levels.
- 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 risk of progression can be assessed by considering the TNM stage, PSA level and Gleason score together.
When is prostate cancer considered to be low-risk?
A prostate cancer tumor is thought to have a low risk of progression (low-risk prostate cancer) if it hasn't spread outside of the prostate and fulfills the following criteria:
- PSA level isn't higher than 10 nanograms per milliliter (ng/ml).
- Gleason score isn't higher than 6.
- Stage: Tumor stage up to T2a without spread to the lymph nodes (N0) or other parts of the body (metastasis, M0).
- Number of affected tissue samples: No more than two of the 10 to 12 tissue samples have cancer cells in them.
- Proportion of tumor cells in the abnormal tissue samples: In those one or two abnormal tissue samples, less than 50% of the tissue is made up of cancer cells.
Using this information, doctors can give you a detailed description of the cancer stage and risk of progression.
What are the treatment options for low-risk prostate cancer?
Men with low-risk prostate cancer have three treatment options: active surveillance, radiotherapy and surgery to remove the prostate.
- Active surveillance involves monitoring the prostate cancer, and only treating it if there are signs that it is progressing. This approach is based on the fact that low-risk prostate cancer often grows very slowly or doesn't grow at all, so treatment isn't always needed.
- In radiotherapy, the tumor cells are destroyed using high-energy rays. This can either be done from outside of the body (external radiotherapy) or from inside the body (internal radiotherapy, or brachytherapy).
- The aim of surgery (radical prostatectomy) is to remove the tumor, together with the whole prostate, seminal vesicles and outer capsule.
The advantage of active surveillance is that surgery or radiotherapy can be avoided in men whose cancer doesn't grow. One disadvantage is that if the cancer progresses it may be discovered too late. It may have already spread to other parts of the body by then (metastasis). Knowing that you have cancer in your body can be distressing too.
Active surveillance involves a lot of check-up appointments. Medical societies in Germany recommend the following:
- A PSA test and palpation examination (feeling the prostate) every three to six months in the first two years.
- A total of three biopsies (tissue samples) in the first three years: One after 6 months, the second one about 12 to 18 months after the first, and a third biopsy at the end of the three years. After that, biopsies should only be done every three years.
If a man has low-risk prostate cancer and he isn't expected to live longer than another 10 years, the cancer isn't likely to grow much more. It may then make sense to have less intensive monitoring without biopsies to check for changes. This approach is called "watchful waiting."
Radiation and the surgical removal of the prostate are also referred to as "curative" treatments because the aim is to remove all of the tumor cells. But a few cancer cells may stay in the body, or new cancer cells might develop. For this reason, men who have had radiotherapy or radical surgery are still advised to have regular PSA tests. Radiotherapy and surgery are about as effective as each other, but they have different possible side effects.
Comparing active surveillance, radiotherapy and surgery
In a study known as the ProtecT trial (prostate testing for cancer and treatment trial), these three treatment options were compared. The study included 1,643 men between the ages of 50 and 69 who had low-risk prostate cancer. They agreed to be randomly assigned to one of the three treatment groups (active surveillance, radiotherapy or surgery to remove the prostate). The treatment outcomes were recorded over an average of ten years, and then compared with each other at the end of the trial.
The following was found over a period of ten years:
- no difference in mortality rate (number of deaths) between the active surveillance, radiotherapy and prostate removal groups,
- slightly more cases of the cancer spreading (metastasis) in the active surveillance group,
- a much higher risk of accidental urine leakage (urinary incontinence) in men who had surgery,
- a much higher risk of erection problems in men who had radiotherapy or surgery (after radiotherapy: particularly in the first six months).
- a somewhat higher risk of accidental stool leakage (fecal incontinence) in men who had radiotherapy.
Other treatment options
There hasn't been enough good research on other treatments such as "high intensity focal ultrasound" (HIFU), cryotherapy (freezing) or hyperthermia treatment (using heat). Because of this, medical societies in Germany don't recommend using them in the treatment of prostate cancer, or only recommend using them for research purposes.
Choosing a treatment
Various factors will influence a man's choice of treatment, including the pros and cons of the different treatment options, and individual factors such as his age and how healthy he is overall. A young and otherwise healthy man who is still expected to live for a long time will probably weigh the pros and cons of the treatment options differently than an older man who may have other medical problems and a shorter life expectancy.
It's best to discuss the pros and cons of the possible treatments with your doctors. Low-risk prostate cancer grows very slowly, so there is plenty of time to think things through before making a decision.
You will find more information about the treatment of localized prostate cancer in the patient information accompanying the German clinical practice guidelines (in German).
Deutsche Gesellschaft für Urologie (DGU). Interdisziplinäre Leitlinie der Qualität S3 zur Früherkennung, Diagnose und Therapie der verschiedenen Stadien des Prostatakarzinoms. AWMF-Register-Nr.: 043/022OL. December 2016. (Leitlinienprogramm Onkologie).
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.
Ramsay CR, Adewuyi TE, Gray J, Hislop J, Shirley MD, Jayakody S et al. Ablative therapy for people with localised prostate cancer: a systematic review and economic evaluation. Health Technol Assess 2015; 19(49): 1-490.
Wolff RF, Ryder S, Bossi A, Briganti A, Crook J, Henry A et al. A systematic review of randomised controlled trials of radiotherapy for localised prostate cancer. Eur J Cancer 2015; 51(16): 2345-2367.
Xiong T, Turner RM, Wei Y, Neal DE, Lyratzopoulos G, Higgins JP. Comparative efficacy and safety of treatments for localised prostate cancer: an application of network meta-analysis. BMJ Open 2014; 4(5): e004285.
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