Complexed PSA Test. Complexed PSA (cPSA) is a form of circulating PSA that is bound to a molecule called alpha1-antichymotrypsin. It represents about 90% of the total PSA in men and is significantly higher in men with prostate cancer than in those with BPH. To date, studies have reported conflicting results on its benefits for diagnosing prostate cancer, although a major 2002 European study was very favorable.
Transition Zone PSA Test.Some tests have been developed to measure the density of the PSA in the transition zone of the prostate gland. (The transition zone is the central area of the prostate that wraps around the urethra.) A major comparison study in 2002 reported more accurate results than with complexed PSA.
Ultrasound (Transrectal Ultrasonography)
An ultrasound procedure called transrectal ultrasonography (TRUS) provides a visual image of the prostate and is used if the DRE indicates the presence of cancer. Ultrasound is not effective as a diagnostic tool by itself because it cannot differentiate very well between benign inflammations and cancer, but the procedure may help to confirm an uncertain preliminary diagnosis and is useful as a guide for needle biopsies. Ultrasound enhancements, such as Doppler imaging or computer modeling techniques called artificial neural networks (ANN), may increase the accuracy of TRUS.
Biopsy
Initial Biopsies. If preliminary tests raise the suspicion of cancer, doctors will perform a biopsy. Biopsy is used to diagnose prostate cancer, and is a very accurate method for predicting the severity of an existing cancer. However, biopsies can still miss cancers if they are very small.
- Core Biopsy. The standard method is called a core biopsy, which uses a spring-loaded biopsy device inserted into the rectum. The device propels a needle into the prostate, obtaining a core of tissue, which is examined by pathologists.
- Fine Needle Aspiration. A more recent procedure called fine needle aspiration is less painful and may be as accurate as a core biopsy if the sample obtained is sufficient for analysis and if it is analyzed by a skilled pathologist.
More than half of the men who have a biopsy experience discomfort and anxiety, with men under 60 reporting higher levels of discomfort than older men. Taking a sedative 1 - 2 hours before the procedure can help reduce distress. Complications of biopsy are low, but urinary tract infection, fever, or bleeding occurs in 0.1 - 4% of men.
Repeat Biopsies. Because a biopsy can miss very small cancer cells, sometimes three or even more biopsies are recommended if cancer is still suspected after negative results, such as in the following circumstances:
- PSA levels are high. Two or more biopsies may be taken if a man has very high PSA levels and still has normal results on a biopsy. Even men with mildly elevated PSA (between 4 and 10 ng/mL) who test negative may be given a repeat biopsy. Cancer will be detected in about 10% of this group. Whether a third biopsy is useful in these men if they still test negative after a second biopsy is uncertain.
- DRE results are abnormal.
- Ultrasound results are abnormal.
- The initial biopsy yields microscopic findings that are suspicious.
- The initial biopsy detects precancerous cells known as high-grade prostatic intraepithelial neoplasia (PIN). No treatment is necessary with this finding, but these patients should be rechecked every 3 to 6 months for the next 2 years, and then annually.
Doctors may also perform a lymph node biopsy to see if the cancer has spread.
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