Prostate Cancer: Diagnosis

Approved by the Cancer.Net Editorial Board, 09/2020

ON THIS PAGE: You will find a list of common tests, procedures, and scans that doctors use to find the cause of a medical problem. Use the menu to see other pages.

Doctors use many tests to find, or diagnose, cancer. They also do tests to learn if cancer has spread to another part of the body from where it started. If this happens, it is called metastasis. For example, imaging tests can show if the cancer has spread. Imaging tests show pictures of the inside of the body. Doctors may also do tests to learn which treatments could work best.

For most types of cancer, a biopsy is the only sure way for the doctor to know if an area of the body has cancer. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory.

This section describes options for diagnosing prostate cancer. Not all tests listed below are commonly used for every person. Your doctor may consider these factors when choosing a diagnostic test:

  • The type of cancer suspected

  • Your signs and symptoms

  • Your age and general health

  • The results of earlier medical tests

Early tests

If prostate cancer is suspected, a physical examination and the following tests may be used to decide if more diagnostic tests are needed:

PSA test. As described in the Introduction and Screening sections, PSA is a type of protein released by prostate tissue that is found in higher levels in blood. Levels can be raised when there is abnormal activity in the prostate, including prostate cancer, BPH, or inflammation of the prostate. Doctors can look at features of the PSA value to decide if a biopsy is needed, such as absolute level, change over time (also known as “PSA velocity”), and level in relation to prostate size.

Free PSA test. There is a version of the PSA test that allows the doctor to measure a specific component, called the “free” PSA. Free PSA is found in the bloodstream and is not bound to proteins. A standard PSA test measures total PSA, which includes both PSA that is and is not bound to proteins. The free PSA test measures the ratio of free PSA to total PSA. Knowing this ratio or percent can sometimes help find out if an elevated PSA level is more likely to be caused by a malignant condition like prostate cancer.

DRE. A doctor uses a DRE to find abnormal parts of the prostate by feeling the area using a finger. It is not very precise and not every doctor has expertise in the technique; therefore, DRE does not usually detect early prostate cancer. See the Screening section for more information.

Biomarker tests. A biomarker is a substance that is found in the blood, urine, or body tissues of a person with cancer. It is made by the tumor or by the body in response to the cancer. A biomarker may also be called a tumor marker. Biomarker tests for prostate cancer include the 4Kscore, which predicts the chances someone will develop high-risk prostate cancer, and the Prostate Health Index (PHI), which predicts the chances someone will develop prostate cancer.

For people diagnosed with prostate cancer by biopsy, there are times when a genomic test, such as Oncotype Dx Prostate, Prolaris, Decipher, and ProMark, can provide additional information to inform a decision about how the prostate cancer is managed. This includes when those with certain low-risk or intermediate-risk localized prostate cancer are considering active surveillance (see Types of Treatment). It also may include using the Decipher test to help decide whether more treatment should be considered in certain patients following surgical removal of the prostate, called prostatectomy. If a biomarker test is used, the results should always be evaluated in combination with all other available information.

Talk with your doctor for more information about biomarker tests, what they mean, and how the results might or might not affect your treatment plan.

This information is based on the ASCO guideline, "Molecular Biomarkers in Localized Prostate Cancer." Please note that this link takes you to another ASCO website.

Making a diagnosis

If the PSA or DRE test results are abnormal, then further tests will be used to confirm whether a person has prostate cancer. Many tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis.

Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. To get a tissue sample, a surgeon most often uses transrectal ultrasound (TRUS, see below) and a biopsy tool to take very small slivers of prostate tissue. Biopsy specimens will be taken from several areas of the prostate. This is done to make sure that a good sample is taken for examination. Most people will have 12 to 14 pieces of tissue removed, and the procedure can take 20 to 30 minutes to complete.

This procedure is usually done at the hospital or doctor’s office without needing to stay overnight. The patient is given local anesthesia beforehand to numb the area and usually receives antibiotics before the procedure to prevent infection. The ultrasound tool is inserted into the rectum and then the biopsy needle is passed through the rectum and into the prostate gland to collect tissue samples.

There is a risk of infection associated with transrectal prostate biopsy, which is why some doctors choose to use transperineal prostate biopsy instead. This biopsy is also guided by TRUS, but the biopsy needle goes through the skin of the perineum and into the prostate gland. The perineum is the space between the scrotum and the anus. By passing the needle through the skin instead of the rectum, this procedure lowers the risk of infection.

A pathologist then analyzes the sample(s) under a microscope. A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease.

Ask to review the results of the pathology report with your health care team.

MRI fusion biopsy. An MRI fusion biopsy combines an MRI scan (see below) with TRUS. Evaluation with a prostate MRI scan has become a routine procedure in clinical practice. The patient first receives an MRI scan to identify suspicious areas of the prostate that require further evaluation. The patient then has an ultrasound of the prostate. Computer software combines these images to produce a 3D image that helps target a precise area for the biopsy. Although it may not eliminate the need for repeat biopsies, an MRI fusion biopsy can better identify areas that are more likely to be cancerous than other methods. An MRI fusion biopsy should only be performed by someone with expertise in the procedure.

Transrectal ultrasound (TRUS). A doctor inserts a probe into the rectum that takes a picture of the prostate using sound waves that bounce off the prostate. A TRUS is usually done at the same time as a biopsy.

Finding out if the cancer has spread

To find out if cancer has spread outside of the prostate, doctors may perform the imaging tests listed below. Doctors are able to estimate the risk of spread, called metastasis, based on PSA levels, tumor grade, and other factors, but an imaging test can confirm and provide information about the cancer’s location.

Imaging tests may not always be needed. A CT scan or bone scan may not be necessary for those with no symptoms and low-risk, early-stage prostate cancer, as determined with information from the PSA test and biopsy. Learn more about when these tests are recommended to find out if the cancer has spread.

For people with advanced prostate cancer, ASCO recommends that 1 or more of the imaging tests below be done to provide more information about the disease and help plan the best treatment. This includes when there is a newly diagnosed, high-risk cancer; if metastasis is suspected or confirmed; if the cancer has returned following treatment; or when the cancer grows during the treatment period. Learn more about this guideline on the ASCO website.

Whole-body bone scan. A bone scan uses a radioactive tracer (Technetium-99) to look at the inside of the bones. The tracer is injected into a patient’s vein. It collects in areas of the bone where metabolic activity has occurred. Healthy bone appears lighter to the camera, and areas of injury, such as those caused by cancer, stand out on the image. It is important to know that structural changes to the bone, such arthritis or bone injuries like fractures, can also be interpreted as abnormal and need to be evaluated by a doctor to make sure they are not cancer.

Computed tomography (CT or CAT) scan. A CT scan takes pictures of the inside of the body using x-rays taken from different angles. A computer combines these pictures into a detailed, 3-dimensional image that shows any abnormalities or tumors. A CT scan can be used to measure the tumor’s size. Sometimes, a special dye called a contrast medium is given before the scan to provide better detail on the image. This dye can be injected into a patient’s vein or given as a pill or liquid to swallow.

Magnetic resonance imaging (MRI). An MRI scan uses magnetic fields, not x-rays, to produce detailed images of the body. An MRI can be used to measure the tumor’s size, and a scan can focus specifically on the area of the prostate or on the whole body. A special dye called contrast medium is given before the scan to create a clearer picture, which is injected into a patient’s vein.

Positron emission tomography (PET) or PET-CT scan (updated 06/2021). A PET scan is usually combined with a CT scan (see above), called a PET-CT scan. However, you may hear your doctor refer to this procedure just as a PET scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive substance is injected into the patient’s body. This substance is taken up by cells that use the most energy or are more biologically active. Because cancer tends to use energy and is biologically active, it absorbs more of the radioactive substance. A scanner then detects this substance to produce images of the inside of the body. For many types of cancer, a PET-CT scan uses fluorodeoxyglucose (FDG) as the substance that is imaged; however, FDG is not a useful substance for initial imaging in prostate cancer and should not be routinely used. If metastasis or recurrence are suspected, a PET scan using gallium-68 PSMA-11 or 18F-DCFPyL may be recommended. In this type of scan, the gallium-68 or fluorine-18 binds to prostate-specific membrane antigen (PSMA), which is often at higher levels in prostate cancer cells, and shows places where the cancer has spread.

Researchers are investigating using different substances with PET scans to find prostate cancer. For example, sodium fluoride is absorbed by bones, and its use in a PET scan may improve the chances of finding prostate cancer that has spread to the bone. Other substances being studied include choline acetate and fluciclovine.

After diagnostic tests are done, your doctor will review all of the results with you. If the diagnosis is cancer, these results also help the doctor describe the cancer. This is called staging.

The next section in this guide is Stages and Grades. It explains the system doctors use to describe the extent of the disease and how the cancer cells look under a microscope. Use the menu to choose a different section to read in this guide.