Core Needle Biopsy
A core needle biopsy is the most common method used to diagnose prostate cancer. This procedure is usually done by a urologist who treats cancers of the genital and urinary tract. Using a transrectal ultrasound (TRUS) to "see" the prostate gland, the doctor chooses the best areas to sample. A thin, hollow needle, is used to go through the wall of the rectum and into the prostate, when the needle is pulled out, it removes a small core of prostate tissue. Most urologists will take about 12 core samples from different parts of the prostate. The biopsy itself takes about 10 minutes and is usually done in the doctor's office under local anesthesia. Some men feel pressure or discomfort during the procedure, but there is typically little to no pain.
Biopsy samples are sent to a lab where they are examined with a microscope to see if they contain cancer cells. If cancer is detected, it will be assigned a grade. This is often expressed as a Gleason Score.
Even though a prostate biopsy collects multiples samples, it is possible to fail to detect cancer when it is present, if none of the biopsy needles pass through it. This is known as a false-negative result. If your doctor still strongly suspects you have prostate cancer, a repeat biopsy may be needed to be sure.
Prostate biopsy results are sometimes called "suspicious." The pathologist may use terms such as prostatic intraepithelial neoplasia (PIN), atypical small acinar proliferation (ASAP, or just atypia), or proliferative inflammatory atrophy (PIA). Suspicious results mean that the cells don't look like cancer, but they don't look quite normal, either. If your biopsy results come back suspicious, you doctor may want to repeat the biopsy.
A staging or mapping biopsy is a relatively new method for assessing prostate cancer. This procedure is very similar to the standard TRUS needle biopsy described above. However, a mapping biopsy removes many more core samples and is performed as an outpatient procedure under general anesthesia. A physician places a grid below the patient's scrotum and takes between 35-80 biopsies of the prostate. This procedure allows the entire prostate to be biopsied and results in the creation of a three-dimensional image of the prostate, including the location of cancer within the gland. This biopsy may be better for determining the size and location within the prostate, and allow for patients and physicians to more appropriately select treatment options. This method of biopsy may help to eliminate errors in the grading of prostate cancer and unnecessary treatments.
As with any medical procedure biopsies can have side effects. Patients may be given antibiotics to take before or after the biopsy to reduce the risk of infection. The following are some common side effects of a prostate biopsy:
- Blood in urine or semen
- Rectal bleeding