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Urology - Prostate Cancer
Testing a blood sample for the level of Prostate Specific Antigen (PSA) plays an important part in the early detection of prostate cancer. PSA is a substance made by the normal prostate gland. Although PSA is mostly found in semen, a small amount is also present in the blood.
Most men have levels under four micrograms per litre (ug/L) of blood. When prostate cancer develops, the PSA level usually goes above 4(or the age-adjusted level); however, a high PSA score does not always indicate cancer.
Although a digital rectal exam (DRE) is less effective than the PSA blood test in finding prostate cancer, this exam can sometimes find cancers in men with normal PSA levels. For this reason, the American Cancer Society guidelines recommend the use of both the DRE and PSA blood test for early prostate cancer detection.
When a doctor suspects prostate cancer based on a patient’s symptoms, the results of a DRE and/or a PSA, the diagnosis must be confirmed by doing a biopsy. The Urologist will use transrectal ultrasound (TRUS) for guidance to insert a narrow needle through the wall of the rectum (local anaesthetic injected first!) and into several areas of the prostate gland. The needle then removes the cylindrical tissue sample, which is sent to the laboratory to test for cancer.
If the biopsy shows the presence of prostate cancer, the pathologist assigns each tissue sample a grade, indicating how far the cells have traveled along the path from normal to abnormal. A tumor with a low grade is likely to be slow growing, while one with a high grade is more likely to grow aggressively or to already have spread outside the prostate (metastasised).
The most widely used grading method for prostate cancer is known as the
"Gleason grading system".
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