Introduction to biopsy
The definition of a biopsy is ‘an examination of tissue to discover the presence, cause, or extent of a disease’. A prostate biopsy will give you a certain diagnosis as to whether you do have prostate cancer. It is the most accurate test available for prostate cancer.
It is the urologist, rather than your GP, who decides whether you need a prostate biopsy taking into account your age, PSA, DRE and MRI scan results. In the NHS, the usual wait time for a biopsy is between 2-6 weeks, with results available after 2 weeks.
Depending on the method of prostate biopsy the procedure will take 10-60 minutes. You will either:
- have your prostate and rectum numbed with a local anaesthetic and biopsies then taken through the rectal wall (transrectal biopsy), or
- have a general anaesthetic as a day case patients and have the biopsies taken through the skin behind the scrotum and in front of the anus (transperineal biopsy). This gives better access to all parts of the prostate and the use of a biopsy grid allows the biopsy needle to be placed with great accuracy.
With both techniques an ultrasound probe is used to measure the size of the prostate and to guide the biopsy needles into the prostate in real time. Between 10-60 samples of tissue are taken, which are then tested microscopically in the laboratory for signs of prostate cancer.
After 1-2 weeks the results of your biopsy will be sent to your urologist in what is called a pathology report. This report will state:
- if cancer was found;
- how many biopsy cores (samples) contained cancer;
- how much cancer was present in each sample;
- the grade of the cancer in each positive core.
When a Pathologist diagnoses prostate cancer under a microscope they assign a Gleason score to each sample. The Gleason score expresses the grade of the cancer, or how aggressive the cancer is and how likely it is to spread.
This score is based on the microscopic appearance of the cells compared to normal prostate cells. If they are not very different, it is a low grade, or an ‘indolent’ cancer. If they are very different, it is a high grade, or an aggressive cancer.
Grade vs. stage
Note that the grade is different to the stage of your prostate cancer, which we described earlier in the MRI section of the Prostate Cancer Guide. Remember, the stage describes how far your cancer has spread. For example, you may have an aggressive prostate cancer (high grade) that has not spread very far (low stage). So we now have two measurements to describe your cancer: the grade and the stage. Together with your PSA prior to prostate biopsy this becomes important later in deciding how to treat it.
The Gleason score for your samples is assessed as follows:
1 or 2 – these are normal prostate cells
3 – fairly abnormal cells detected
4 – moderately abnormal cells
5 – highly abnormal prostate cells
The most common Gleason score out of all of your samples is taken, and then added to the second most common Gleason score out of all your samples to give you a total Gleason score out of 10. This standard method of reporting ensures that your urologist fully understands the likely behaviour history of your particular prostate cancer and so know how best to advise you.
Now that both you and your urologist have a clear idea of both the grade and the stage of your prostate cancer, you are now in a very good position to decide on how to treat it. Your urologist will talk your best options through with you as it ultimately is a personal decision, but one heavily influenced by various factors that they will explain to you.