PSA stands for prostate specific antigen. It is a protein produced by prostate cells – both normal and abnormal. PSA is detected with a simple blood test. When cancer is present, the level of PSA rises as more of the protein leaks into the bloodstream.
The PSA test does not tell you for sure that you do or do not have prostate cancer. Only about 4 in 10 men with a higher than normal test are found to have prostate cancer! However the test is useful. It guides the decision to have further investigations.
Recently, studies have found that an elevated PSA test in younger men can predict higher risk of developing prostate cancer up to 25 years into the future (5). This can be helpful in deciding whether a man should be regularly tested (screened) for prostate cancer.
PSA will usually rise slowly with age, and a rapid rise can be caused by infection. However a rapid rise or a higher than normal PSA also raises a concern about cancer and this will be investigated further.
Many authorities advise that if you have a PSA test, you should also have a rectal examination. This is because not all cancers produce PSA. The rectal exam can pick up some cancers that are missed by the blood test.
Because the rectum is located just behind the prostate, and cancer most often grows on that side of the gland, a doctor can sometimes feel a cancer by placing a gloved finger inside the rectum. This test may be uncomfortable but is rarely painful. A rectal examination (also known as a digital rectal examination) is less likely to pick up early cancers than the PSA test, and so cancers detected in this way are often larger. If this test is performed in conjunction with a PSA test the chance of picking up all cancers is better. If both tests are positive, there is a higher chance you do have prostate cancer.
The next step: Biopsy
If you have a PSA test and it appears abnormal or increasing, your doctor may repeat the test or order investigations to rule out other causes for the increase. If the abnormal PSA level persists or the rectal examination is abnormal, the next step in most cases is to refer you to a urologist. The urologist may repeat some tests and discuss the possibility that you have cancer. He or she may recommend a biopsy of the prostate.
To perform a biopsy, an ultrasound probe is placed in the rectum to help the doctor to see and target the prostate. The doctor then takes 12 or more samples of prostate tissue from several different areas of the gland.
Biopsies are usually done under anaesthetic but there still may be some discomfort.
There is a small risk of infection. Antibiotics are given to reduce this risk. You may notice blood from the rectum or in the urine or ejaculate after a biopsy. This can last for some time before settling.
A biopsy is needed to find out if you have prostate cancer. It also gives information about the cancer’s ‘grade’ (how rapidly it is likely to grow). Combining information from the PSA test, rectal examination and biopsy helps the doctor to know what risk the cancer poses to your health and life.
It is your decision whether to have a test. You need to decide what is best for you.