Prostate Cancer: Biopsy & Diagnosis
Dr. Taneja talks about recent advances in imaging for biopsy and computer-guided treatment in treating prostate cancer.
If you have an abnormal digital rectal exam or elevated PSA, the next step is a prostate biopsy, which is used to diagnose prostate cancer. This is an office-based procedure performed under local anesthesia and usually takes about 15 minutes.
An ultrasound probe is placed into the rectum and 12 biopsy ‘cores’ (tissue samples) are extracted from the prostate. The needles are evenly spaced in a ‘template’ that maps to different areas of the prostate, allowing doctors to determine which area of the prostate may be cancerous. If there is a mass that was detected during the DRE, the biopsy can be directed toward that area of the prostate.
The tissue removed during the biopsy is then sent to a pathologist, who examines it at high magnification under a microscope to determine how much it differs from normal prostate tissue.
There is increasing evidence that a standard 12-core biopsy may miss significant cancers. Smilow surgeons were among the first in the world to use computer-guided biopsy technology to perform prostate biopsy. This new technology, available under the name TargetScan, appears to be very promising.
Dr. Samir Taneja discusses all aspects of imaging and biopsy for prostate cancer in this educational video, as well as recent advances that have been made in this area. Click here to view this video.
Interpreting biopsy results for prostate cancer
The results of the prostate biopsy are interpreted based on a grading system, known as the Gleason score, that categorizes the severity of cancer. Each core is given a grade of 1 to 5, with 1 being the least aggressive cancer, and 5 being the most aggressive cancer. The most common Gleason value observed is then added to the second most common Gleason value to give a final Gleason score ranging from 2 to 10. The overwhelming majority of Gleason scores are 6 and 7.
In addition to the Gleason score, other important factors in interpreting biopsy results include:
- How many cores were positive
- Where the positive cores were located
- The percentage of positive cores
The biopsy may also detect pre-cancerous lesions that, while not cancerous, may indicate an increased risk of developing prostate cancer in the future.
PIN, or prostatic intraepithelial neoplasia, is one type of pre-cancerous lesion. It is very common, found in almost half of all men by the time they reach age 50. It represents glandular changes and does not necessarily mean cancer, but it is associated with an increased risk of prostate cancer.
Urologists at NYU Langone Medical Center were the first to study what happens to men with PIN over time. Our research showed that 25% of men with PIN will develop prostate cancer within three years. The detection rate of prostate cancer was independent of changes in PSA. Therefore, if PIN is discovered on biopsy, we recommend a repeat biopsy after 1 year if the PSA is rising, or at 3 years if the PSA is stable.
ASAP, or atypical small acinar proliferation, is another type of pre-cancerous lesion. These cells are very atypical, but there is usually insufficient tissue to make the diagnosis of cancer. ASAP is associated with a 40–50% chance of finding prostate cancer on subsequent biopsy. A close follow-up and repeat biopsy are recommended if ASAP is discovered.
Check out our FAQ on Prostate Cancer Screening & Biopsy for more in-depth information
Staging prostate cancer
If prostate cancer is detected in a biopsy, the next step is to determine if it has spread to other parts of the body—known as staging the cancer.
A digital rectal exam will indicate if the prostate cancer is confined to the prostate, or if it has spread to neighboring organs. Imaging studies, which may include a bone scan, X-ray, MRI or CT scan, will also help determine if the cancer has spread to other areas of the body.
You may read more about prostate cancer staging at the American Cancer Society Web site.