Diagnosis of Prostate Cancer
When a digital rectal exam (DRE) or a PSA test reveal abnormal results, the next step is further testing to determine whether prostate cancer is present, or another cause may be to blame.
Your doctor will evaluate your test results and any symptoms you may be experiencing and recommend the next tests you may need. The most common diagnostic tests for the prostate include:
Ultrasound: A transrectal ultrasound involves inserting a small ultrasound probe into the rectum. The ultrasound machine sends out sound waves and then measures the “echoes” that bounce back off body structures to create an image of the “landscape” of the structure. It can provide images that show the extent of prostate enlargement or abnormalities.
MRI: Magnetic resonance imaging (MRI) is sometimes used to create a more detailed set of images than an ultrasound can provide. Results will be reported as a PI-RADS score.
- PI-RADS 1: very low—clinically significant cancer is highly unlikely to be present
- PI-RADS 2: low—clinically significant cancer is unlikely to be present
- PI-RADS 3: intermediate—the chance of clinically significant cancer is neutral
- PI-RADS 4: high—clinically significant cancer is likely to be present
- PI-RADS 5: very high—clinically significant cancer is highly likely to be present
Biopsy: A biopsy entails taking a sample of tissue for examination under a microscope. A biopsy can be taken via a needle or needles inserted into the prostate, or a larger sample can be obtained surgically (anesthesia is used, and your doctor will offer you appropriate pain relief). Often, ultrasound is used to guide the needles to the exact area of concern. Biopsy technology is advancing quickly and can be combined with imaging techniques to increase accuracy:
- TRUS-guided biopsy: A trans-rectal ultrasound–guided biopsy is the most common way prostate cancer is diagnosed in the US. An ultrasound probe is placed in the rectum to allow visualization of the prostate. Then at least 12 needles are placed into the prostate to take samples that are examined for abnormal cells. (Twelve needles sounds like a lot, but the more varied the sample, the greater the chance of catching any abnormal cells.) If a patient had magnetic resonance imaging (MRI) before the biopsy, the MRI images may help target areas that looked suspicious.
- Trans-perineal biopsy: A biopsy sample can also be obtained by placing a needle through the perineum, the skin between the scrotum and anus.
- Incidental procedures: Sometimes, doctors performing surgery in a nearby area actually see something amiss with the prostate and can take a sample during the same procedure.
Regardless of which procedure is used to take a sample, the prostate tissue is then examined under a microscope by a pathologist, to confirm the presence or absence of cancerous cells.
Biopsy technology continues to improve. New research is isolating better and better ways to increase accuracy of biopsies to zero in on problem areas and achieve the goal of a minimally-invasive biopsy procedure that has the greatest chance of sampling cells, with minimal damage to surrounding tissues. Targeted, or fusion biopsies are increasingly being utilized at select centers that use an MRI, in addition to the ultrasound, to better visualize tumors within the prostate and help guide biopsy needles.
Regardless of which diagnostic tests were used, your doctor will review your test results with you and discuss what the next steps will be—whether it’s best to repeat the tests after an interval of time, or whether you should begin treatment for prostate cancer.
Learn more about how active prostate cancer is assessed, or “staged.”