PSA is a protein (called prostate specific antigen) produced by cells that line the small glands inside the prostate. When a man has prostate cancer, his PSA levels tend to increase, which is why a PSA test is often used by physicians to screen for prostate cancer.
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To conduct a PSA test, a physician will take a blood sample and send it to a laboratory for analysis. A PSA test result is an important factor when determining prostate cancer diagnosis, plan and treatment. However, an elevated PSA does not always mean a man has prostate cancer. Additionally, a low PSA does not mean that cancer is not present.
Doctors often recommend PSA testing in men 55 and older. However, your doctor may recommend testing your levels at an earlier age if you have known risk factors for prostate cancer, including family history of the disease or the known presence of a germline mutation.
In general, doctors often consider PSA levels of 3.9 ng/mL and lower to be normal depending on your age. It is also important for your doctor to track any increases in your PSA levels as these increases may suggest the presence of cancer even if your PSA is in the normal range.
According to American Cancer Society, men with a PSA level between 4.0 and 10.0 ng/mL have a 25% chance of having prostate cancer. For men with a PSA level greater than 10.0 ng/mL, the chance of prostate cancer is over 50%.1
Consult with your physician regarding PSA results and PSA ranges.
As mentioned above, a high PSA doesn’t always mean a man has prostate cancer. PSA levels can be elevated because of several benign conditions.
Doctors use a Digital Rectal Exam (DRE) to screen for cancer. This procedure is completed to examine the health of the prostate gland and to check for abnormalities and prostate cancer. The prostate can be felt through the side of the rectal wall. Please note that not all parts of the prostate can be felt on this exam.
A DRE is an in-office examination where your doctor or nurse gently inserts a lubricated, gloved finger into the anus to estimate the size of the prostate and feel for lumps or other abnormalities.
Due to the additional pressure on the prostate, some men may feel discomfort or the urge to urinate during the exam.
If the PSA or DRE tests are suspicious for prostate cancer, your doctor will likely request further testing such as prostate biopsy and/or imaging.
As mentioned, rising PSA levels and an abnormal DRE may suggest cancer is present. To confirm the presence of prostate cancer, your doctor will order a prostate biopsy. The biopsy is the small samples of tissue from the prostate that will be reviewed by a pathologist to determine if cancer is present. A urologist often completes this process.
To prepare for the biopsy, the doctor may do the following:
Please talk with your doctor about their full list of instructions before your biopsy.
During the biopsy procedure, the doctor will use TRUS (mentioned below) to guide a thin, hollow needle through the rectal wall into the prostate. In some instances, the doctor will order an MRI before the biopsy to locate abnormalities within the prostate that may represent prostate cancer. The needle retrieves several thin cylindrical sections, or cores, of prostate tissue. Most urologists take 6-12 core samples in total from different areas of the prostate.
Some doctors may recommend imaging guidance during the prostate biopsy procedure to help ensure that the best samples are being removed. Transrectal Ultrasound (TRUS) is a form of imaging guidance.
A small probe, about the width of a finger, is inserted into your rectum. The probe emits soundwaves that enter the prostate and create echoes. Those echoes are picked up by the probe and sent to a computer that turns them into an image of the prostate. This procedure often takes less than 10 minutes and is done in a doctor’s office or outpatient clinic.
Biopsy samples will be sent to a lab and examined by a pathologist for cancer cells. If the pathologist can see cancer, a grade will be assigned. This grade is called the Gleason grade. Prostate cancer Gleason grades range from 1 to 5. Higher Gleason grades usually represent more aggressive prostate cancer. The Gleason grades will be available on the pathology report.
Pathologists review biopsy tissue and assign it a Gleason grade based on the appearance of the cells. If cancer is present, it will be assigned two Gleason grades ranging from 1 to 5. The primary grade, or first number shown, is the most common Gleason pattern (grade) found in the biopsy. The second number is the second most common Gleason pattern (grade). These two numbers are added together for a Gleason score. Gleason scores range from 2 to 10 with most prostate cancer ranging from 6 to 10. An example Gleason score is 3+4=7. In this example, 3 is the primary pattern, and 4 is the secondary. When added together they equal 7.
Another term you may hear regarding Gleason scores is Grade Groups. Gleason scores have been divided into groups ranging from 1 to 5. Gleason score and Gleason grades determine the Gleason group.
Gleason scores play a vital role in determining treatment decisions. First developed in the 1970s, Gleason scores have been used to assess the aggressiveness of patients’ prostate cancer. Unfortunately, errors when determining biopsy Gleason score are common. Gleason grading and scoring are largely subjective, and not all pathologists may agree on a Gleason grade, especially on small tissue samples obtained at biopsy. Therefore variation between pathologists does occur.
Additional testing can be done to get a more accurate assessment of your cancer aggressiveness. The Prolaris test is one such test that combines clinical and pathologic features (findings on DRE, PSA and Gleason score) with a tumor molecular measure derived from your biopsy tissue to deliver a unique view into how fast cancer cells are dividing and cancer aggressiveness.