A Prostate Specific Antigen (PSA) Test
The prostate specific antigen (PSA) test is a blood test that may be offered to you as routine screening in the context of a checkup by a primary care physician or urologist. But using the test for routine screening is controversial. Elevated results on a PSA test may occur for reasons other than cancer, such as an enlarged prostate, benign prostatic hyperplasia (BPH), or an infection in the prostate called prostatitis. Men who receive an elevated result may be referred for further testing. For this reason, the test should only be done after an informed conversation between doctor and patient takes place. The American Cancer Society uses these parameters to evaluate PSA results:
A PSA test result below 4 nanograms per milliliter (ng/ml) means that 85 percent of the time, you won’t have prostate cancer.A PSA between 4 and 10 is associated with a 1 in 4 chance of having prostate cancer.If your PSA is greater than 10, you have a 1 in 2 chance of having prostate cancer.
But doctors have not adopted a uniform system for interpreting PSA. Thresholds for concern and reference ranges vary considerably. (1) If your PSA test results are elevated you will likely be advised to have more tests. Like the PSA test, suspicious findings on a DRE do not necessarily mean that you have prostate cancer. Rather, the results are considered in combination with PSA test results and symptoms a patient may have. Concerns have mounted recently about primary care doctors’ ability to use the DRE effectively. A recent study published in the Annals of Family Medicine found that only one-half of surveyed primary care doctors feel comfortable performing DREs. In fact, the authors of that study recommended against primary care doctors performing them. (2)
Transrectal Ultrasound and Real-Time Biopsy
If you receive an elevated PSA result or have suspicious findings on a DRE, your physician might recommend that you undergo a prostate biopsy. The most common test used for this is a transrectal ultrasound (TRUS), in which an ultrasound probe is inserted into the rectum and sound waves are used to create an image of the prostate gland. During the ultrasound, biopsy samples are often collected from several areas of the prostate with a hollow needle. This is referred to as real-time biopsy or a transrectal prostate biopsy. The biopsy samples are then analyzed in a pathology laboratory to see if cancer cells are present. Important benefits of combining the two procedures include:
The ability to better target suspicious areas of high-grade (aggressive areas) and clinically significant tumors.Helping to avoid false-positive diagnoses and overdiagnosis or sampling areas unlikely to contain cancer or aggressive cancer.Getting a high-quality biopsy. (3)
MRI Ultrasound Targeted Prostate Biopsy
Magnetic resonance imaging (MRI) guided biopsies are also being used more frequently, with ultrasound or alone, to help guide a prostate biopsy. MRI scans are capable of revealing potentially cancerous areas in more detail than ultrasound. Studies have emerged suggesting that fusing the two techniques — using MRI to identify suspicious areas before the transrectal ultrasound and biopsy procedure — might identify cancer more accurately than a TRUS biopsy alone. For example, a landmark study led by researchers at the National Cancer Institute’s urologic oncology branch found that the MRI-fused ultrasound technique detected more aggressive prostate cancer and fewer low-risk prostate cancers. A joint statement issued by the American Urological Association and Society of Abdominal Radiologists supports fused MRI-ultrasound for men on active surveillance — men who, along with their doctors, have opted to watch a slow-growing cancer rather than treat it aggressively — and for men who have received elevated PSA test result but whose previous biopsies have tested negative for cancer. (4)
Preparing for Your Prostate Biopsy
To prepare you for the test, your urologist should tell you about the risks and benefits of having a biopsy. The most common complications following a prostate biopsy are having blood in the urine, rectum, or semen, a urinary tract infection, and acute urinary retention. These side effects usually pass quickly. Less commonly, erectile dysfunction occurs. After this discussion with your doctor, you will be asked to sign a consent form. You may also be asked to discontinue some medications, such as anticoagulants, nonsteroidal anti-inflammatory drugs, herbal supplements, and vitamins for one to several days. On the night before the biopsy is scheduled, your doctor may ask you to do an enema at home. Eating lightly the day before is often recommended. You also may be asked to take an antibiotic the day before or on the day of the biopsy. (5) When you come in for the procedure, you will be asked to lie still on your side with your knees bent. The doctor will insert a small finger-size ultrasound probe into your rectum. The probe lets the doctor see images of your prostate gland and helps determine where to inject a local anesthetic. The images the doctor sees also help guide the biopsy needle. Your doctor will take 10 to 18 tissue samples from the prostate gland, which will then be sent to a pathology lab. The entire procedure takes about 10 minutes. Your doctor will contact you with results usually within about a week. After the procedure, your rectum may feel sore. You may see small amounts of blood in your stool, urine, or semen that last for several days or weeks. Antibiotics might be prescribed for several days to prevent infection.
Making Sense of Prostate Biopsy Results
If your biopsy reveals that some cells look abnormal, but may or may not be cancer, your doctor might recommend another biopsy. If your biopsy comes back positive, it means cancer cells were detected. Your pathology report will include:
A Gleason score, which helps doctors predict how fast-growing the prostate cancer isThe number of biopsy samples that contain cancer out of the total number sampledA diagnosis of each core or biopsy sampleThe percentage of cancer in each sampleWhether the cancer is on one or both sides of the prostate gland (6)
Understanding Your Gleason Score
Your Gleason score is the sum of various “grades” the pathologist has given samples taken from the prostate gland. The more aggressive the cancer looks, the higher the grade. The lowest Gleason score you can receive for prostate cancer is a 6. These cancers are considered low-grade and unlikely to be aggressive. A Gleason score of 8 to 10 is more aggressive and more likely to grow and spread quickly. A cancer with a Gleason score of 9 to 10 is likely to be even more aggressive. (6)
