Prostate Cancer: Diagnosis

Approved by the Cancer.Net Editorial Board, 01/2017

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. To see other pages, use the menu.

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 whether an area of the body has cancer. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis, but this situation is rare for prostate cancer. For example, a biopsy may not be done when a patient has another medical problem that makes it difficult to do a biopsy, or when a person has a very high PSA level and a bone scan that indicates cancer.

This list describes options for diagnosing this type of 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 medical condition

  • The results of earlier medical tests

Preliminary tests

In addition to a physical examination, the following tests may be used to diagnose prostate cancer:

  • 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 a man's 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, such as absolute level, change over time, and level in relation to prostate size, to decide if a biopsy is needed. In addition, a version of the PSA test allows the doctor to measure a specific component, called the “free” PSA, which can sometimes help find out if a tumor is noncancerous or cancerous.

  • 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; therefore, most men with early prostate cancer have normal DRE test results. 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 a man will develop high-risk prostate cancer, and the Prostate Health Index (PHI), which predicts the chances a man will develop prostate cancer.

Confirming the diagnosis

If the PSA or DRE test results are abnormal, then the following tests can help confirm a diagnosis of cancer:

  • PCA3 test. The Prostate CAncer gene 3 (PCA3) assay looks for the PCA3 gene in a man’s urine. Unlike PSA, the PCA3 gene is only found in prostate cancer cells. Using a urine test, a doctor can find out whether this gene is present in the body. This test does not replace PSA. It is used along with a PSA to help decide if a prostate biopsy is needed.

  • 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.

  • Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. To get a tissue sample, a surgeon most often uses TRUS and a biopsy tool to take very small slivers of prostate tissue. Biopsy specimens will be taken from multiple areas of the prostate. This is done to ensure that a good sample is taken for examination. Most men will have 12 to 14 pieces of tissue removed, and the procedure can take 20 to 30 minutes to complete.

    A pathologist then analyzes the sample(s). A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease. A patient usually can have this procedure 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.

    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. 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 the precise area to be biopsied. 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. MRI fusion biopsy should only be performed by someone with expertise in the procedure.

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. Learn more about when these tests are recommended to find out if the cancer has spread.

  • Bone scan. A bone scan uses a radioactive tracer to look at the inside of the bones. The tracer is injected into a patient’s vein. It collects in areas of the bone and is detected by a special camera. Healthy bone appears gray to the camera, and areas of injury, such as those caused by cancer, appear dark.

  • Computed tomography (CT or CAT) scan. A CT scan creates a 3-dimensional picture of the inside of the body using x-rays taken from different angles. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. A CT scan can also 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 liquid to swallow.

  • Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. MRI can also be used to measure the tumor’s size. A special dye called contrast medium is given before the scan to create a clearer picture. This dye can be injected into a patient’s vein or given as a liquid to swallow.

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. Or, use the menu to choose another section to continue reading this guide.