Raised or rising PSA - what happens next? > Grading and staging tests
PSA measurement and digital rectal examination are both important for staging cancer, but you will almost certainly have to undergo some further tests.
Ultrasound
Ultrasound may be used to assess the size and texture of the prostate; the specific technique is called transrectal ultrasonography (or TRUS for short). A lubricated probe is inserted into the rectum, where it passes high-frequency sound waves through the prostate. Computer analysis of the echoes, which vary according to the density of the tissues the waves are passing through, produces an image of the prostate that can then be seen on a screen. Ultrasound is a relatively simple and safe procedure that is not too uncomfortable, but without a biopsy it cannot be used to tell definitively whether or not cancer is present.
Ultrasound-guided biopsy
Ultrasound-guided biopsy is used to obtain tiny samples of tissue from your prostate that can then be sent to the pathology laboratory for analysis under a microscope. The pathologist can check whether cancer is present and, if it is, grade it. You will probably be recommended for biopsy, an outpatient procedure, on the basis of your PSA level.
Using ultrasound for guidance, a fine, automated needle is inserted into the back passage until it reaches the prostate (shown in the diagram on the below). The test is not too painful (not much worse than a visit to the dentist), but you may feel a sharp needle prick as 6–12 tissue samples are taken, even if a local anaesthetic has been used. The results should be available within a few days. Remember, though, that biopsies of the prostate are only tiny samples of the whole gland, so small cancers may sometimes be missed. If the PSA continues to rise in spite of a negative biopsy result a further set of biopsies may be required. Several studies have shown that after 3 sets of negative biopsies prostate cancer is unusual because the rise in PSA that triggered the biopsy is usually the result of benign prostatic hyperplasia (BPH).
| When a prostate biopsy is performed, a lubricated ultrasound probe is inserted into the rectum to give an accurate view of the prostate. Samples of tissue (usually 6–12) are collected using a fine automated needle. |
You will usually be given antibiotics (tablets or an injection) for 24 hours or immediately before the procedure, and you will be told to continue taking the prescribed antibiotic tablets for several days afterwards. For several weeks after the procedure, you may notice blood in your urine, semen and/or bowel motions. This is quite normal, but if you have any worries, consult your doctor. Urinary infections can occasionally occur as a consequence of the biopsy – if you feel a burning sensation on urination, notice that your urine is cloudy and/or smelly, find that you have to urinate more frequently than normal and/or you develop a temperature, have shaking attacks and feel generally unwell, contact your doctor. He will probably prescribe more antibiotics or, very occasionally, admit you to hospital for treatment using an intravenous drip.
There is no evidence that biopsies cause prostate cancer to spread. The ability to spread (to metastasise) to other parts of the body, such as the skeleton, depends on the characteristics of the cancer cells themselves and tends to occur quite late in the disease.
Bone scans
Bone scans are a means of checking whether the cancer has spread (metastasised) around the body. Two to three hours before you have the scan, a mixture containing radioactive particles (radionuclides) will be injected into your arm. The particles then spread around your body; their pattern, which shows up on the scanner, can reveal ‘hot spots’, which are dark areas of abnormal blood flow – a sign that cancer may be present. Remember that ‘hot spots’ can be the result of other diseases, such as arthritis in the joints and spine, so further testing may be necessary to clarify the cause of an abnormal scan. Do not be concerned about the use of radiation here – the amount is so low that the risk to your health is negligible.
| Bone scans from a man with prostate cancer. The dark spots show the presence of secondary cancer in the bones. |
MRI
MRI, or magnetic resonance imaging, is a technique whereby a strong magnetic field and radio signals are used to examine sequential cross-sections of the body. The images that result are highly detailed – the urologist can use them to assess the extent of the cancer in the prostate and to check whether any secondary tumours have formed in other regions. The procedure is completely painless, but some people find being in the scanner a little claustrophobic. The results should be available within a few days.
| An MRI scan showing cancer (arrowed) in the prostate. |
If you have any metal implants, such as a pacemaker or coronary artery stents, it may not be possible to perform an MRI scan, so a CT scan will probably be arranged.
CT scanning
CT, or computerized tomography, is similar to MRI in that the technique produces images of sequential slices through the body, but it uses X-rays to build up the images. CT scanning is not as accurate as MRI, but is much less claustrophobic. Occasionally, CT scanning is used to guide biopsy needles to obtain tissue samples from enlarged lymph nodes or other soft tissues. It also helps when planning radiotherapy treatment fields.
Why scans are not always necessary
Although you might think that every man who has been diagnosed with prostate cancer requires scanning, in fact, in men with a PSA below 10 ng/mL, the chances of a positive scan are so low that they are generally not recommended. Many patients feel reassured to know that their scans are clear, but remember that bone scans can give false-positive results and MRI scans can also sometimes be misleading as they cannot reliably detect microscopic spread outside the prostate.