Further Tests for Prostate Cancer
Following referral for suspected prostate cancer, you will be recommended for various tests, the first of which should now be a non-invasive MRI scan. A magnetic resonance imaging (MRI) scan creates a cross-section of the soft tissues around the selected part of the body by using magnetic fields. The machines for these scans use a tunnel in which the body is located. Some may find this a little claustrophobic, but the head usually remains clear of the tunnel, so that the patient can see some daylight. The machine can seem rather noisy and the patient is asked to keep as still as possible during the process. It is possible to speak to the radiographer through a microphone/headphone system. The procedure is quite harmless.
In the past the test has normally been done after a biopsy as a further check to see whether there is any spread outside the prostate. Currently clinicians prefer to use a multi- parametric MRI scan of the prostate area ideally before a biopsy is considered. Significant tumours can be detected more accurately, therefore allowing any biopsy to be guided more precisely. If no significant tumour is found on the MRI, then there may be no need for an immediate biopsy.
Special 3-Tesla MRI machines (with a more powerful magnetic field) are now in use in several hospitals, which can detect a tumour in much greater detail. These will become the gold standard in the future, though it will be some while before they come into use in many hospitals.
Recent advances in MRI scanning techniques and the introduction of advanced software has led to greater accuracy in identifying the position of any tumour and its potential aggressiveness.
Biopsy is a procedure in which a number of small samples of an organ are extracted and examined under a microscope to identify the presence or not of cancer. A trans-rectal ultrasound (TRUS) and biopsy of the prostate is done at the hospital as an out-patient. The test itself normally takes no longer than about ten minutes, although it may be necessary to remain in hospital for a little longer. A local anaesthetic is given, but some men can still find the procedure uncomfortable.
A lubricated ultrasound probe is first inserted into the back passage in order to provide a ‘map’ of the prostate. The doctor will then pass a fine needle through the rectal wall into the prostate to extract 8–12 samples of tissue cores. These are sent for examination to a pathologist, who will then determine whether any cancerous tissue is present. Antibiotics are given prior to and immediately following the procedure. There may be a little blood in the urine and/ or the back passage for up to three weeks after a biopsy, and blood in the semen for 4–6 weeks. This is not a cause for concern and is normal, but any other symptoms should be referred immediately to your GP or hospital.
As a biopsy takes tiny sample cores from the prostate, it is possible that the needle may miss the cancer. The greater the number of samples taken, the more likelihood of finding the cancer. Greater sampling, however, can lead to increased risk of complications. However, new techniques (see Fusion Guided Biopsy below) mean that better accuracy is now possible.
Template (or Perineal) Biopsy
Because a standard biopsy may miss finding smaller cancers, there is a growing shift towards using a template biopsy, a more precise test which can sample the whole prostate. This is done when suspicions are high but normal biopsy results are inconclusive. Many urologists now prefer to recommend this method to their patients. The procedure is performed under a general anaesthetic. A grid will be placed over the perineal area (between the anus and scrotum) through which many more needles can be inserted to take samples. As well as being more accurate, a template biopsy is considered safer, as there is less risk of infections from untreatable bacteria from a standard TRUS biopsy.
Fusion Guided Biopsy
Recently new software has been devised that ‘fuses’ the MRI images with the realtime ultra-sound probe. The MRI images are overlaid onto the ultrasound image which enables the urologist doing the procedure to pinpoint the suspicious areas with much greater accuracy. Although currently under development, it may lead to less samples being taken and, for those who may need further biopsies, less occasions where a repeat biopsy may be needed.
This test is to show whether the disease has spread to the bones. A small amount of low-dose radio-active material is injected into the arm about three hours before the scan. The scan takes about 45 minutes, and images of any bones showing the disease will show up on the scan. A bone scan will not usually be done unless the PSA score is greater than 10 and MRI and biopsy samples indicate a high-grade cancer. It is painless and quite harmless.
These tests are not normally part of the standard diagnosis for prostate cancer, but may sometimes be recommended.
Bone density test
A bone mineral density test (BMD), sometimes called a DEXA scan (dual energy X-ray absorbtiometry) measures bone mass, helps determine bone strength, and can predict the risk of future fracture. It may be requested through the GP before long-term hormone treatment (see more about this in the Treatment Options section) in order to establish a baseline value, and repeated during the treatment course.
This is an examination of the bladder by passing a thin flexible tube through the urethra. It is occasionally recommended to eliminate any possibility of bladder disease.