How Is Prostate Cancer Diagnosed?

Photo of a pathologist examining a specimen under a microscope

If your PSA test is abnormal, a small piece of tissue is removed from the prostate and looked at under a microscope.

If your prostate specific antigen (PSA) test is abnormal, doctors may do more tests to find or diagnose prostate cancer.

A biopsy is when a small piece of tissue is removed from the prostate and looked at under a microscope to see if there are cancer cells.

A Gleason score is determined when the biopsy is looked at under the microscope. If there is a cancer, the score indicates how likely it is to spread. The score ranges from 2 to 10. The lower the score, the less likely it is that the cancer will spread.

A biopsy is the main tool for diagnosing prostate cancer, but a doctor can use other tools to help make sure the biopsy is made in the right place. For example, doctors may use a transrectal ultrasound, when a probe the size of a finger is inserted into the rectum and high-energy sound waves (ultrasound) are bounced off the prostate to create a picture of the prostate called a sonogram. Doctors also may use magnetic resonance imaging (MRI) to guide the biopsy.


If prostate cancer is diagnosed, other tests are done to find out if cancer cells have spread within the prostate or to other parts of the body. This process is called staging. Whether the cancer is only in the prostate, or has spread outside the prostate, determines your stage of prostate cancer. The stage of prostate cancer tells doctors what kind of treatment you need.