Biopsy: What is a Prostate Biopsy and how is it performed?
A prostate biopsy is a procedure by which samples of tissue are removed from suspicious areas of the prostate gland for microscopic examination by a pathologist. A biopsy is absolutely necessary to confirm the presence of cancer and should be undertaken prior to any treatment of the disease. Biopsies and examination under a microscope are required to definitively diagnose any kind of cancer – skin, lung, breast, etc. The biopsy also provides us with a wealth of information about the specific characteristics and grade of the cancer, such as the Gleason score.
When performing a biopsy, the doctor will use a transrectal ultrasound (TRUS) imaging for guidance in order to insert a narrow needle through the wall of the rectum into the prostate gland. Doctors can also perform the biopsy through the perineum, the area between the rectum and scrotum. The needle removes a tiny core of tissue (usually measuring about ½-inch by 1/16-inch) that is sent to the laboratory to see if cancer is present. Although the procedure may sound painful, for most men, a biopsy causes little discomfort because it is performed with an instrument called a biopsy gun which inserts and removes the needle in a fraction of a second. In addition, a local anesthetic can be used to numb the area. Patients are advised to confirm this with their doctor prior to the procedure in order to know what to expect. The procedure can be done in the doctor’s office and usually takes only about 15 minutes.
The prostate biopsy has traditionally involved obtaining at least six core samples of tissue. This procedure, known as the sextant biopsy, draws two tissue samples from the base, mid-gland and apex for a total of six core samples. Studies have shown that increasing the number of samples can significantly increase the detection of malignancy. The number of biopsy samples taken now ranges from 6 to 18 or more. The 5-region biopsy approach obtains additional samples from the mid-gland tissue and the lateral zones or lobes on each side of the gland. When a very large number of samples are obtained (25 samples or more), this approach is called “saturation biopsy”.
Standard transrectal approach biopsies can be limited in their ability to access and sample the apical prostate (lowest portion), anterior prostate (transitional zone) and the most postero-lateral (left and right) aspects of the gland, especially with a larger gland. Therefore, we recommend a type of biopsy known as a “template-guided transperineal 3-dimensional mapping (3-DMP)”. The risk of infection is also less with the 3-DMP approach as is the degree of rectal bleeding, since the potentially “contaminated” rectal wall is not pierced, while only a betadine cleansed “sterile” perineum is pierced using the 3-DMP method. Other benefits include being better suited for large glands (office biopsies often miss right and left lateral lesions, where prostate cancer is common); there is less chance of hitting a critical vessel; and the physician can guide the biopsy to an area of concern if using color flow Doppler ultrasound, unlike the literal “shots in the dark” when using standard grey scale imaging. Its only drawback is that it is much more costly. The information obtained by your biopsy will be very important in guiding your treatment decisions, should your results indicate the presence of cancer. In that event, we recommend requesting a copy of the pathologist’s report for your own files. We also advise patients to obtain a second opinion on the pathology report from one of the leaders in the field, since Gleason scores are subjective and dependent on the expertise of the practitioner.