Diagnostic Tools

The DRE and PSA tests cannot diagnose prostate cancer; they merely indicate that further testing is needed.

Percent Free to Total PSA
This test measures how much PSA circulates freely in the blood and how much is bound with other proteins. The more free PSA that is present the more likely a man is to not have cancer. If a man has an elevated total PSA, but most of it is “free PSA,” then it is most likely coming from BPH rather than cancer. If most of the total PSA is coming from PSA that is bound to proteins, it is more likely that the patient has cancer. According to the Prostate Cancer Foundation (PCF) in one study, researchers used a free-PSA cutoff range of 19% in men with total PSA levels between 3 and 4 and detected 90% of all cancers. In another study of men with total PSA levels between 4 and 10, biopsies were performed only in men with free PSA of less than 25% of the total PSA. They detected 95% of the cancers and reduced unnecessary biopsies by 20%.

Transrectal Ultrasound (TRUS)
The Transrectal Ultrasound (TRUS) procedure uses sound waves to create an image of the prostate to help guide the biopsy needles. It has been shown that TRUS alone is of limited, if any, value in the diagnosis of prostate cancer and is now used primarily to guide biopsy needles.

Prostate Biopsy
Abnormal findings in either the DRE or PSA may indicate the need for a biopsy. During a biopsy, a TRUS is used to view and guide a needle (or multiple needles) into the prostate to take small samples of tissue. Typically, a prostate cancer biopsy employs a multi-needle device that is able to take six or more tissue samples simultaneously from different parts of the prostate to be sure that cancerous tissue is not missed. This procedure is typically performed using local anesthesia.

A biopsy is the only way to confirm or diagnose the presence of prostate cancer. The biopsy procedure may cause some discomfort or pain, but the procedure is short, and it can usually be performed without an overnight hospital stay. After a biopsy, blood may be present in the urine, semen and/or bowel movements, but these symptoms generally disappear after a few weeks.

While biopsies are the most accurate means of detecting the presence of cancer in the prostate, it is possible to miss a significant cancer during a biopsy – or receive a false-negative result. The biopsy is only a sampling of tissue from various parts of the prostate. If very strong signs of cancer were present prior to the biopsy, such as a prostate lump felt during the DRE, a very high PSA and/or an elevated PSA with a very low percentage of free PSA, but no cancer was found, the patient should discuss repeating the biopsy with his physician.

The information and opinions expressed on this web site are not an endorsement or recommendation for any medical treatment, product, service or course of action by the Prostate Cancer Coalition of North Carolina or its officers and directors. For medical, legal or other advice, please consult appropriate professionals of your choice.

Prostate Cancer Coalition of North Carolina (PCCNC)
5905 Shamrock Road
Research Triangle Park, NC 27713
919.321.0365
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