What does a TRUS guided prostate biopsy involve?
The transrectal ultrasound may be performed in your urologist's office or in the radiology department, depending on your institution. In preparation for the study, you may be asked to take an enema to clean stool out of the rectum and to take some antibiotics around the time of the study. You will be asked to stop taking any aspirin or nonsteroidal anti-inflammatory medications, such as ibuprofen (Motrin or Advil) for about 1 week prior to the biopsy to minimize bleeding. The doctor will ask you to lie on your side with your legs bent and brought up to your abdomen. The ultrasound probe, which is a little larger than your thumb, is then gently placed into the rectum. This can cause some transient discomfort that usually stops when the probe
is in place and completely goes away when the probe is removed. Men who have had prior rectal surgery, who have active hemorrhoids, or who are very anxious and cannot relax the external sphincter muscle may have more discomfort. Once the probe is in a good position, the prostate will be evaluated to make sure that there are no suspicious areas on the ultrasound. Ultrasound looks at tissues by sound waves. The probe emits the sound waves, and the waves hit the prostate and are bounced off the prostate and surrounding tissue. The waves then return to the ultrasound probe, and a picture is developed on the screen. The sound waves do not cause any discomfort. Prostate cancer tends to cause less reflection of the sound waves, a trait referred to as hypoechoic, so the area often looks different in an ultrasound image than the normal prostate tissue. After the prostate has been evaluated, biopsies are obtained. The transrectal ultrasound allows the urologist to visualize the location for the biopsies. A minimum of six to eight biopsies are obtained and more frequently twelve. These biopsies are distributed between the top, the bottom, and the middle aspect of the prostate on each side. If you have a large prostate gland, have suspicious areas on ultrasound, or have had prior negative prostate biopsies, more biopsies may be obtained.
Side effects of TRUS guided prostate biopsy include transient discomfort related to the ultrasound probe, the needle guide, and the biopsy itself. After the TRUS biopsy one may experience blood in the urine, the semen (ejaculate), and/or in the stools. A urinary tract infection and/or acute prostatitis may occur and would present with frequency of urination, burning, and perineal discomfort and, in some cases, a fever.
Are all prostate cancers the same? Are there different grades?
Not all prostate cancers are the same. Prostate cancers may vary in the grade of the cancer and the stage of the cancer.
The grade of a cancer is a term used to describe how the cancer cells look. That is, whether the cells look aggressive and not very similar to normal cells (high grade) or whether they look very similar to normal cells (low grade). The grade of the cancer is an important factor in predicting long-term results of treatment, response to treatment, and survival. With prostate cancer, the most commonly used grading system is the Gleason scale. In this grading system, cells are examined by a pathologist under the microscope and assigned a number based on how the cancer cells look and how they are arranged together (Figure 7). Because prostate cancer may be composed of cancer cells of different grades, the pathologist assigns numbers to the two predominant grades present. The numbers range from 1 (low grade) to 5 (high grade). Typically, the Gleason score is the total of these two numbers; for example, a man with a Gleason grade of 2 and 3 in his prostate cancer would have a Gleason score of 5. An exception to this occurs where the highest (most aggressive) pattern present in a biopsy is neither the most predominant nor the second most predominant pattern. In this situation, the Gleason score is obtained by combining the most predominant pattern grade with the highest grade. Occasionally, if a small component of a tumor on prostatectomy is of a pattern that is higher than the two most predominant patterns, then the minor component is noted as a tertiary grade to the pathology report.
Figure 7. Gleason grading system of prostate adenocarcinoma.
Reprinted with permission from JI Epstein, Campbell's Urology, (7th Ed). Copyright © 1997 W.B. Saunders Co.
Low score cancers are those with a Gleason score of 2, 3, or 4. Intermediate score cancers are those with a Gleason score of 5, 6, or 7. And high score cancers are those with a Gleason score of 8, 9, or 10. The speed of growth and the aggressiveness of the cancer increase with the Gleason score. Gleason scores 8 through 10 are highly aggressive tumors and are often difficult to cure.
Sometimes these cancers are so abnormal that they do not even produce PSA. The grade of the cancer
identified by the biopsies may differ from the grade that is present in the entire prostate because it is possible that the biopsy may not identify areas of highergrade cancers.
Other abnormalities that may be noted on the biopsy result are PIN and atypical glands. PIN, or prostatic intraepithelial neoplasia, is identified by the pathologist examining the prostate biopsies. PIN has been thought to be a precancerous lesion. More recently, PIN has been divided into two types, low-grade PIN and high-grade PIN, based on how the cells look. Low-grade PIN does not appear to have any increased risk of prostate cancer. High-grade PIN, however, is often found in association with prostate cancer. In 35-45% of men who undergo a repeat biopsy for high-grade PIN, prostate cancer cells are present in the repeat biopsy. If your doctor has performed multiple biopsies (i.e., 10-12) then the recommendation is to consider a delayed repeat biopsy. If your doctor only did six biopsies, then an immediate repeat biopsy is indicated. "Atypical gland; suspicious for cancer" is noted on the pathology report when the pathologist sees an atypical area that has most of the features of cancer, but a definitive diagnosis of cancer cannot be made due to the small size of the area and the small number of abnormal cells present. Repeat biopsy in patients with this diagnosis have up to a 60% chance of having prostate cancer present in a repeat biopsy. Thus, the finding of atypical gland; suspicious for cancer warrants an immediate rebiopsy (within 3 months) with increased number of biopsies from the abnormal area and the areas nearby. If no cancer is found on the repeat biopsy then close follow-up with PSA, digital rectal examination, and periodic biopsy may be needed. See pccnc.org/early.