Prostate biopsy is a procedure in which small samples are removed from a man's prostate gland to be tested for the presence of cancer. It is typically performed when the scores from a PSA blood test rise to a level that is associated with the possible presence of prostate cancer.
The procedure, usually an outpatient procedure, requires a local anesthetic, with fifty-five percent of men reporting discomfort during the biopsy. The most frequent complication of the procedure is bleeding in the urine for several days, some bleeding in the stool for several days, and blood in the ejaculate for several weeks afterwards.
The procedure may be performed transrectally, through the urethra or through the perineum. The most common procedure is transrectal, and may be done with tactile finger guidance, or, more commonly and precisely, with ultrasound guidance.
About a dozen samples are taken from the prostate gland through a thin needle - about six from each side. If the procedure is performed transrectally, antibiotics are prescribed to prevent infection. An enema may also be prescribed for the morning of the procedure. In both the transrectal and the transperineal procedure, the doctor inserts an ultrasound probe into the rectum to help guide the biopsy needles. A local anesthetic is then administered into the tissue around the prostate, similar to the local anesthetic administered for a dental procedure. A spring-loaded prostate tissue collection needle is then inserted into the prostate, through the rectum (or more rarely through the perineum), about a dozen times. It makes a clicking sound, and there may be considerable discomfort.
Negative Biopsy
Biopsies detect prostate cancer in about 25% of men with abnormal screening tests. However a negative biopsy does not ensure the absence of disease. Repeat prostate biopsies are positive in about 25-30% of patients whose initial biopsy was negative.
During a biopsy procedure, less than 1 percent of the entire prostate gland is sampled, so men can harbor prostate cancer in spite of having a negative initial biopsy.
Recently in order to address this problem, researchers have examined the ability of mitochondrial DNA to help diagnose prostate cancer in negative biopsy samples.
Magnetic Resonance Imaging (MRI)-guided Biopsy
For the last two decades, transrectal ultrasound (TRUS) guided biopsy has been used to diagnose prostate cancer in a "blind" fashion because prostate cancer cannot be seen on ultrasound due to poor soft tissue resolution. MRI, in contrast, can identify and characterize prostate cancer. There are two forms of MRI-guided prostate biopsy: one that uses a fusion technology between US and MRI and another using MRI-alone. In the fusion US/MRI prostate biopsy, a prostate MRI is performed before biopsy and then, at the time of biopsy, the MRI images are fused to the ultrasound images to guide the urologist to the targets. In the second type of MRI-guided prostate biopsy, MRI is used at the time of biopsy. For US/MRI biopsy, a urologist performs the procedure whereas for MRI-guided prostate biopsy, a radiologist performs the procedure. US/MRI guided prostate biopsy has shown to be superior to standard TRUS-biopsy in prostate cancer detection. The multidisciplinary team approach between radiologists and urologists in prostate cancer diagnosis using MRI is benefiting men with prostate cancer. NIH-funded studies are underway to further clarify the benefits.
The tissue samples are then examined under a microscope to determine whether cancer cells are present, and to evaluate the microscopic features (or Gleason score) of any cancer found.
Tissue samples can be stained for the presence of PSA and other tumor markers in order to determine the origin of maligant cells that have metastasized.[
