Diagnosis & staging of prostate cancer
Digital rectal examination (DRE)
If cancer is present in the prostate gland it may feel hard and knobbly, whereas with BPH it is usually enlarged, firm and smooth. However, sometimes the prostate may feel normal, even when cancer cells are present.
You will be recommended to have a blood test called PSA.
- A PSA test is generally said to be in the normal range when it is reported
to be between 0 and 4 nanograms per milliliter, sometimes abbreviated as ng/mL
on the lab report.
- If the results are in the high range (reported to be greater than 10 ng/mL),
then your doctor will suggest a biopsy, which is the only test to actually
diagnose prostate cancer.
- Sometimes, PSA results are in the “borderline high” range. This occurs when
the results are between 4 and 10 ng/mL. PSA test results in this range can be
confusing and do not always mean that cancer is present. Certain other
conditions, such as benign prostatic hyperplasia (also called BPH — a type of
noncancerous prostate enlargement) and prostatitis (inflammation of the
prostate), may cause an abnormal PSA result. Mostly, the doctor will recommend
a biospy to ensure that a cancer is not
Trans-rectal ultrasound scan (TRUS)
Ultrasound scans use sound waves to build up a picture of the
inside of the body. To scan the prostate gland a small probe is passed into the back passage and the image of the prostate appears on a screen. This type of scan is used to measure the size and density of the prostate. A sample of cells (biopsy) can be taken at the same time for examination under the microscope by a pathologist.
The scan may be uncomfortable but it only takes a few minutes.
If the initial tests (rectal examination, PSA or ultrasound) show that there is a possibility
of cancer, you may be asked to have a biopsy, in which a sample of cells is taken from the prostate to be looked at under a microscope. The biopsy is usually done at the same time as the ultrasound.
A needle is passed through the wall of the back passage (rectum) and into the prostate. This test is usually uncomfortable, and can sometimes be painful, but it does not need a general anaesthetic.
Antibiotics are given to reduce the risk of infection. For a few days following this test you may notice bleeding when passing water, when having your bowels open or after sex.
Unfortunately, even if there is cancer in the prostate it may not be picked up on biopsy. This occurs in approximately one fifth of men. If a biopsy is negative it may need to be repeated (which will detect most of the cancers
missed first time) or the PSA may be measured again after a few months and the biopsy repeated if the PSA level starts to rise.
There is a more detailed way of biopsying the prostate gland, called transperineal template prostate biopsy. Rather than the standard 12 cores of prostate tissue taken in the TRUS biopsy technique, a template biopsy will take 30-40 cores. This does require a general or spinal anaesthetic and specialised equipment.
If the biopsy shows that a cancer is present further tests will be needed to check whether the
cancer has spread beyond the prostate gland. These may include:
Isotope bone scan
A very small amount of mildly radioactive liquid is injected into a vein, usually in your arm.
A scan is then taken of the whole body. Abnormal bone absorbs more of the radioactive substance than normal bone and shows up on the scan as highlighted areas (known as 'hot spots').
After the injection you will have to wait for up to three hours before the scan can be taken, so it is a good idea to take a book or magazine with you.
The level of radioactivity that is used is very small and does not cause any harm.
This scan can also detect other conditions affecting the bones such as arthritis, so further tests such as an X-ray of the abnormal area may be necessary to confirm that it is cancer.
A CT scan takes a series of pictures of an area of the body. These are fed into a computer
which creates detailed pictures of the inside of the body. A CT scan may show if the cancer has spread beyond the prostate to other parts of the body such as the lymph glands
The scan takes from 10-30 minutes. You may be given a drink or injection of a dye, which allows particular areas to be seen more clearly. For a few minutes, this may make you feel hot all over. If you are allergic to iodine or have asthma you could have a more serious reaction to the injection, so it is important to let your doctor know beforehand.
You will probably be able to go home as soon as the scan is over.
Magnetic Resonance Imaging (MRI or NMR
This test is similar to a CT scan but uses magnetism instead of
X-rays to build up cross-sectional pictures of your body. An MRI scan is the most accurate way we have of determining if a prostate cancer has spread beyond the margin of the prostate. More recently specialised MRI techniques called multparametric MRI (mMRI), have become available in some hospital in the UK. These offer the hope of being able to diagnose areas of prostate cancer and thus guide where the biopsies need be taken.