Prostate cancer diagnosis is carried out following screening for the disease using the Prostate Specific Antigen (PSA) blood test and the digital rectal examination (DRE). Screening may be carried out in older men who show no symptoms of the disease if they chose to do so. The same tests may be also used in men who start to show prostate cancer signs or symptoms to help detect the disease. If results of the PSA blood test or the DRE are abnormal, a biopsy is carried out in order to check for cancer cells in the prostate glands.
Prostate Specific Antigen (PSA) Blood Test and Digital Rectal Examination (DRE)
Prostate cancer testing methods used for screening include the following tests:
- The DRE involves the doctor inserting a lubricated gloved finger into the lower part of the rectum to feel for any lumps or abnormalities on the prostate glands.
- The PSA blood test is often used alongside the DRE for screening purposes. PSA is a protein that is produced by the prostate glands. PSA is therefore present in all men, but is usually seen at elevated levels in the blood of men who have prostate cancer. Therefore, by measuring the PSA level, the PSA blood test can give an indication of whether a man is more likely to have prostate cancer.
Reliability of PSA Blood Test and DRE for Prostate Cancer Screening
Some men who have prostate cancer do not show elevated PSA levels when screened using the PSA blood test, although the majority of prostate cancer cases do. In addition, some men may have an elevated PSA level due to reasons other than the presence of prostate cancer. The PSA blood test may show an elevated PSA level because of the following:
- The presence of benign prostatic hyperplasia (BPH), a non-cancerous enlargement of the prostate glands.
- The presence of prostatitis, an inflammation of the prostate gland.
- The general overall PSA level in men increases with age.
As such, prostate cancer screening tests do not give a may not always distinguish between BPH and prostate cancer. The PSA blood test and DRE therefore do not give a definitive diagnosis of prostate cancer, but can suggest that prostate cancer may be present.
Prostate Cancer Diagnosis Following the PSA Blood Test and DRE
A doctor uses both results from the PSA blood test and the DRE in order to determine what follow-up is required. The following scenarios may occur:
- If a raised PSA level is seen but the DRE is normal and there are no other symptoms of prostate cancer, the recommendation may be to repeat the tests at regular intervals to check for any changes.
- If there are prostate cancer symptoms present, but the PSA blood test shows a 'normal' PSA level and the DRE shows no abnormalities, other tests can be undertaken in order to check for another problem. These may include imaging tests to help find the problem, or a urinary test to check for any infection.
- If the PSA blood test shows an elevated PSA level alongside the doctor finding abnormalities within the prostate region using the DRE, a prostate biopsy is carried out in order to determine if the patient actually has the prostate cancer. This diagnosis of prostate cancer requires removal of several small tissue samples from the prostate glands, which are then analysed under the microscope to detect for the presence of cancer cells.
A PSA blood test and the DRE are the first tests to be carried out in order to help detect prostate cancer. These tests can be undertaken for older men who show no symptoms of the disease as well as for men who are experiencing symptoms of prostate cancer or other prostate problems. If prostate cancer is suspected, a diagnosis is then made by a prostate biopsy.
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Prostate Cancer Screening - the Debate Continues
Source:
NCI 2009, ‘Prostate-Specific Antigen (PSA) Test’, Updated 3 March 2009, Accessed 18 May 2010
Christine Redmond - My interest in science and healthcare has seen me working in the laboratory with tiny cells and DNA to helping set up a cancer clinical ...
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