How Is Prostate Cancer Diagnosed?
Medically reviewed by Doru Paul, MD
Prostate cancer is detected using a digital rectal exam and blood tests. A healthcare provider may refer you to a urologist (who specializes in the urinary tract and reproductive systems) if they discover or suspect a mass. The urologist will use imaging tests and perform a prostate biopsy to diagnose prostate cancer.
Prostate cancer develops when abnormal cells in the prostate grow out of control and form a tumor. The prostate is a small gland in the male reproductive system that helps with semen production.
Most people with prostate cancer are diagnosed before symptoms occur after routine screening tests. Prostate cancer is a slow-growing disease and does not usually cause symptoms in the early stages.
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Medical History
A healthcare provider will ask about any prostate cancer symptoms you have and how long you've had them. They will also ask questions to determine what risk factors you may have for prostate cancer. Risk factors include a family history of the disease, age, and exposure to certain chemicals (e.g., agricultural chemicals).
Digital Rectal Exam (DRE)
A healthcare provider may perform a digital rectal exam (DRE) if you have prostate cancer symptoms or risk factors. A DRE involves a healthcare provider inserting a gloved, lubricated finger into your rectum to feel the prostate and detect any abnormalities.
Bumps, hard areas on the prostate, or an enlarged prostate are possible signs of prostate cancer. These signs will require further investigation.
Prostate-Specific Antigen (PSA) Blood Tests
A blood test that measures the amount of prostate-specific antigen (PSA) is the standard screening test for prostate cancer. PSA is a protein made by cells in the prostate. Both healthy cells and cancer cells produce PSA, but cancer cells tend to produce higher levels. Elevated levels of PSA in the blood can be a sign of prostate cancer.
There is no specific PSA number that definitively indicates prostate cancer. Some ranges are considered "normal" or "high":
Normal range: PSA levels below 4 nanograms per milliliter (ng/mL) are generally considered normal. Levels higher than 4 ng/mL may indicate prostate cancer. About 15% of people with a PSA below 4 ng/mL are diagnosed with prostate cancer if a biopsy is performed.
Borderline range: About 25% of people with PSA levels between 4–10 ng/mL have prostate cancer.
High range: People with a PSA above 10 ng/mL have a 50% chance of having prostate cancer.
Other factors besides prostate cancer can affect PSA levels. Benign (non-cancerous) conditions, such as prostatitis (inflammation of the prostate) and benign prostatic hyperplasia (enlarged prostate), are associated with high PSA levels. Certain medications and older age can consistently raise PSA levels. Recent ejaculation and even activities like riding a bicycle can temporarily raise PSA levels.
PSA alone cannot be used to diagnose prostate cancer. A healthcare provider may repeat the test in a couple of weeks if your results indicate elevated PSA levels.
A healthcare provider may order different types of PSA tests:
Age-specific density: PSA levels are often higher in older men. Some healthcare providers compare PSA results with those of other men of the same age.
Percent-free PSA: This is the percentage of PSA in the blood that is not attached to proteins. A percent-free PSA test may be ordered if your initial PSA results are in the borderline range (4–10 ng/mL). A low percentage of percent-free PSA means you have a higher chance of having prostate cancer.
ProPSA: This measures the number of precursors of prostate-specific antigen, which are released from cancerous cells and tissues.
PSA density: People with large prostates have higher PSA levels. This test measures the size (volume) of the prostate and divides the PSA number by the prostate volume. Higher PSA density is associated with a greater likelihood of prostate cancer.
PSA velocity: This measures how quickly PSA increases over time. A rapid increase may suggest cancer. This test is often not recommended as a reliable diagnostic tool.
Prostate Health Index (PHI)
The Prostate Health Index (PHI) is a calculation that combines the total PSA, free PSA, and proPSA measurements. The PHI helps healthcare providers determine the likelihood of detecting prostate cancer with a biopsy.
Some evidence suggests that PHI can be an effective tool for screening for prostate cancer and help prevent unnecessary biopsy procedures. The PHI may also help healthcare providers, such as an oncologist (who specializes in cancer), figure out the best prostate cancer treatments.
Transrectal Ultrasound (TRUS)
A transrectal ultrasound (TRUS) is an imaging test that checks the prostate for signs of cancer. A healthcare provider inserts a thin ultrasound probe into the rectum. The probe uses sound waves to take a picture of the prostate. You will be given an enema before the procedure and may feel mild discomfort during the ultrasound.
If the TRUS detects a mass or other abnormalities, a biopsy is required to determine whether it is cancerous. A healthcare provider will often perform a biopsy at the same time as the TRUS.
Prostate Biopsy
A healthcare provider will likely recommend a biopsy if the PSA, DRE, or other tests indicate the possible presence of prostate cancer. They will remove a small tissue sample from the prostate to send to a lab, where it's examined under a microscope to check for cancer cells.
A core needle biopsy is the most common method used to diagnose prostate cancer. The healthcare provider will remove tissue samples by inserting a thin needle into the prostate.
This may be done through the wall of the rectum (transrectal biopsy) or through the skin between the anus and scrotum (transperineal biopsy). The needle is then removed with a small sliver of prostate tissue. This process is repeated about 12 times to take tissue samples from different parts of the prostate.
The prostate biopsy procedure takes about 10 minutes. You will receive anesthesia beforehand to numb the area. You may be given antibiotics afterward to reduce the risk of infection if a transrectal biopsy is performed. A pathologist (who specializes in cells, tissues, and organs) will examine the samples under a microscope to look for cancer cells.
MRI Fusion Biopsy
Magnetic resonance imaging (MRI) scans create detailed pictures of the body using strong magnets and radio waves. An MRI can provide very clear pictures of the prostate and nearby tissues and help determine if a mass is malignant (cancerous) or benign.
An MRI fusion biopsy combines an MRI scan, TRUS, and biopsy into one procedure. A healthcare provider will first perform an MRI to look for signs of cancer on the prostate. They will then perform the TRUS.
Computer software combines pictures from the MRI and TRUS to produce 3D images that help target the specific area where a tissue sample will be retrieved (biopsy). The tissue samples are then sent to the lab, where a pathologist will check them under a microscope for cancer cells.
Multiparametric MRI (mp-MRI)
Multiparametric MRI (mp-MRI) is a technique that helps easily identify cancer in prostate tissue. This procedure may also give an idea of how aggressive the cancer is, meaning how quickly it will grow. An mp-MRI can also help identify if the cancer has spread to surrounding tissues near the prostate or other areas of the body.
A healthcare provider will perform a standard MRI. They will use one other type of MRI (e.g., diffusion-weighted imaging or dynamic contrast-enhanced) to compare images from the two imaging tests and find abnormalities in the prostate.
Stages of Prostate Cancer
The stage of prostate cancer describes where the cancer is located, whether it has spread, and where (how far) in the body it has spread. Staging helps oncologists develop a treatment plan and determine a person's chances of recovery (prognosis).
There are two types of staging for prostate cancer:
Clinical staging: This is based on the results of the BRE, PSA test, imaging tests, and a Gleason score (grade of the tumor). Healthcare providers also use these results to determine whether further diagnostic tests (e.g., MRI) are needed.
Pathologic staging: A healthcare provider can examine cancer cells to learn more about the disease if you have prostate surgery to remove part of or the entire gland. This may help them determine the most effective treatments for you.
A healthcare provider completes clinical staging at the time of diagnosis. Pathologic staging is done after surgery. Pathologic staging is usually more accurate since it happens after the prostate tissues have been removed and thoroughly examined in the lab.
Gleason Score Grading
A pathologist will examine prostate cancer cells under a microscope and give it a Gleason score and grade. This staging system is based on how much the cancer looks like healthy tissue. The lower the score, the more cancer cells look and act like healthy cells. A higher score indicates aggressive cancer that is more likely to grow and spread quickly.
The Gleason score grading includes:
Gleason 6 or lower: Cancer cells look similar to healthy cells and are likely to grow and spread very slowly.
Gleason 7: Cancer cells look somewhat similar to healthy cells and are likely to grow and spread slowly.
Gleason 8–10: Cancer cells look very different from healthy cells and are likely to grow and spread quickly.
Clinical Staging of Prostate Cancer
A healthcare provider clinically stages prostate cancer at the time of diagnosis using the TNM system. This system is based on five factors:
The extent of the primary tumor (T)
Whether cancer has spread to lymph nodes near the prostate (N)
Whether cancer has metastasized (spread) to more distant parts of the body (M)
PSA levels at the time of diagnosis
The Gleason score or grade of the tumor
Prostate cancer stages include:
Stage 1: The cancer is slow-growing, and the tumor is confined to only one-half of one side of the prostate. The tumor cannot be felt during a DRE, PSA levels are low, and the Gleason score is 6 or lower, meaning cancer cells resemble healthy cells under a microscope.
Stage 2: The tumor is confined to the prostate and may be felt during DRE. It is small but may grow and spread. PSA levels range from medium to low, and the Gleason score is 7 or 8.
Stage 3: The tumor can range from small to large and has spread outside of the prostate gland into nearby tissues or organs, such as the bladder or rectum. PSA levels are high, the Gleason score is 9 or 10, and the tumor is likely to grow and spread.
Stage 4: The cancer is advanced and has spread beyond the prostate to nearby lymph nodes as well as other, more distant parts of the body.
Screening for Related Conditions
Some conditions that affect the urinary tract and prostate gland cause symptoms similar to those of prostate cancer. Tests and procedures help determine whether your symptoms are caused by cancer or another condition.
Related conditions include:
Benign prostatic hyperplasia (BPH): An enlarged prostate that is common in older men
Bladder cancer: Cancer that begins in the cells of the bladder
Prostatic stones: Nodules (stones) that develop in or around the prostate gland due to BPH or prostatitis
Prostatitis: Inflammation of the prostate gland that is usually caused by an infection
Urethritis: Inflammation of the urethra
Urinary tract infection (UTI): An infection in any part of the urinary system (e.g., bladder, kidneys, urethra)
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A Quick Review
Prostate cancer develops when abnormal cells in the prostate grow out of control and form a tumor. The prostate is a small gland in the male reproductive system that helps with semen production. Prostate cancer is detected through screening tests, such as the PSA test and a DRE, often before symptoms develop.
Imaging tests, including a TRUS and MRI, can look for signs of cancer in the prostate and nearby tissues. A biopsy can confirm a diagnosis and help oncologists determine the stage and grade of the cancer.
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