Prostate Cancer Diagnosis

Physicians at MD Anderson specialize in diagnosing prostate cancer. They have the expertise and technology to evaluate the growth pattern and extent of each particular cancer, which will affect treatment.

If you have prostate cancer, it’s important to get an accurate diagnosis as soon as possible. This helps increase the odds for successful treatment and recovery.

If you have symptoms that may signal prostate cancer, your doctor will ask you questions about your health, your lifestyle, and your family medical history.

One or more of the following tests may be used to find out if you have cancer and if it has spread. These tests also may be used to find out if treatment is working.

Digital rectal exam (DRE)

The simplest screening test for prostate cancer is the digital rectal exam (DRE). The health care provider gently inserts a gloved forefinger into the rectum to feel the prostate gland for enlargement or other abnormalities, such as a lump.

The DRE is not a definitive cancer test, but regular exams help detect changes in the prostate over time. These changes might signal cancer or pre-cancerous conditions.

Although this test usually is not as reliable as the PSA blood test (see below), a DRE may be able to find cancer in a man with a normal PSA level. A DRE also may be used to tell if prostate cancer has spread or returned after treatment.

Prostate-specific antigen (PSA) test

Prostate-specific antigen (PSA) is a protein produced by the cells of the prostate gland. It is found mostly in semen, but a small amount is in the blood as well.

A blood test measures the amount of PSA circulating in the blood. This level is used to assess prostate cancer risk. A PSA of 4 nanograms per milliliter or lower is considered normal. A higher PSA level usually means a higher chance of having prostate cancer.

PSA tests have limitations. Prostate tissue and prostate cancer both produce PSA. Sometimes prostate cancer does not produce much PSA. In other cases, high PSA levels can be caused by factors other than cancer. These include:

• Enlarged prostate, also called benign prostatic hyperplasia (BPH), which is found often in older men
• Age: PSA levels normally go up slowly as men age
• Prostate infection or inflammation, which also is called prostatitis
• PSA may rise briefly after ejaculation, then return to normal levels

Certain conditions may make PSA levels low, even when a man has prostate cancer. These include:

• Some drugs used to treat BPH or other conditions
• Certain herbal medicines or supplements
• Obesity

Despite its limitations, PSA testing has helped detect prostate cancer in countless men. In 1984, before PSA testing was available, the chance of finding early prostate cancer was about 50%. In 1993, after PSA testing became widely used, that figure jumped to more than 90%.

Men with very low PSA levels may need to be tested every two years. If PSA is higher, the doctor may recommend more frequent testing.

Because prostate cancer develops slowly, physicians usually do not recommend the PSA test for men who are older than 75 or have other significant health issues.

PSA tests can also be used in men who have been diagnosed with prostate cancer. For instance, they may:

• Help doctors plan treatment or further testing
• Determine if cancer has metastasized (spread beyond the prostate)
• Find out if treatment is working or cancer has returned
• Aid in active surveillance (also called watchful waiting) by showing if cancer is growing

Imaging exams

If prostate cancer is suspected, your doctor may order imaging tests to get a better view. Imaging exams can help identify the area of the prostate that should be sampled and studied under a microscope. They can also determine how far cancer has spread beyond the prostate. Imaging tests may include:

• Transrectal ultrasound: During a transrectal ultrasound, a small probe is inserted through the rectum. This probe generates high-energy sound waves that bounce off your tissue and create a picture of your prostate gland on a screen. This picture can be examined for abnormalities or tumors.
• Magnetic resonance imaging (MRI): An MRI uses magnetic fields and radio waves to generate pictures of the soft tissue and organs of the body. Your doctor may order this to see if and how far prostate cancer has spread to other organs.

Learn more about our diagnostic imaging procedures

Biopsy

In a biopsy, a small amount of suspected cancer tissue is removed and examined under a microscope. This is the only way to tell for sure if you have prostate cancer.

Biopsies for prostate cancer are usually outpatient procedures done in a doctor’s office or another facility. A local anesthetic like dentists use, often lidocaine is injected into the area close to the prostate to make the procedure more comfortable.

In most cases, a small transrectal ultrasound (TRUS) probe with an imaging device is inserted into the rectum. The doctor can then view the prostate on a video screen. Using this image as a guide, the physician injects a thin needle through the wall of the rectum into the prostate. Several tiny samples of tissue are removed.

Based on the patient’s situation, MD Anderson also conducts biopsies where the needle is inserted through the perineum (the skin between the scrotum and the anus) instead of the rectum. Fusion biopsies, which use special software to target abnormalities found in an MRI, are also an option.

Sometimes a biopsy will not find prostate cancer, even if it is there. If your doctor is concerned that you may have prostate cancer based on a follow-up PSA test, a second biopsy may be performed.

In other cases, the biopsy will not show cancer but will reveal changes in the size and shape of the cells in the prostate. This is called prostatic intraepithelial neoplasia (PIN). Patients whose cells look significantly abnormal have a higher risk of developing prostate cancer. Men with this condition, called high-grade PIN, should undergo regular prostate cancer screenings, including digital rectal exams and PSA tests.

What are the grades and risk groups for prostate cancer?

If a biopsy finds prostate cancer, it will be classified using the Gleason grading system. This helps doctors choose the best treatment options and predict how quickly the cancer is growing.

To grade the cancer, a specialist will examine the arrangement patterns of the two most common cell types and compare them with normal prostate cells. If the prostate cancer cells in the sample look almost normal, they receive a grade of 1. If the cells are highly irregular compared to normal cells, they will receive a higher grade, up to 5. The Gleason score is the sum of the grades assigned to each cell type. The higher the Gleason score, the more aggressive the cancer.

Gleason grades 1 and 2 are rarely seen since the changes are so small and unlikely to be discovered. That means the usual lowest grade is 3. Gleason scores are categorized as follows:

• 3+3 are low grade and have the lowest risk of harm. This is also called Gleason Grade Group 1.
• 3+4 and 4+3 are intermediate risk, the latter being the more aggressive type. These are also called Gleason Grade Groups 2 and 3, respectively.
• 4+4 through 5+5 are the highest risk. These are Gleason Grade Groups 4 and 5.

Prostate cancer risk assessment

If you are diagnosed with prostate cancer, your doctor will also make a series of estimates about the risk that the disease may be harmful in the future. Factors include:

• Gleason score
• PSA level
• Clinical stage, which is based on findings of the digital rectal exam (DRE) and/or an imaging exam.

There are three main risk groups, each of which has its own set of treatment options.

Low risk:

• Less than 10% chance of having spread to other parts of the body
• Low risk of progressing if not treated
• PSA less than 10 ng/mL
• Gleason score of 6 or lower
• No tumor felt on DRE or feels contained within the prostate gland with only a small abnormal area

Intermediate risk:

• 10% to 15% chance of having spread
• Higher chance (up to 70% over 15 years) of progressing if not treated
• PSA of 10 to 20 ng/mL
• Gleason score of 7
• The tumor can be felt on one or both sides of the prostate on DRE, but it seems to be contained within the gland

High risk:

• Aggressive features that increase the chance of spreading now or in the future
• PSA over 20 ng/mL
• Gleason score of 8 to 10
• The tumor can be felt on DRE and seems to have spread outside the gland

If the prostate cancer is determined to be intermediate or high risk, imaging tests such as bone scans and CAT (computed axial tomography) or MRI (magnetic resonance imaging) scans may be used to determine if the cancer has spread.

Taken together, the disease risk status and imaging results will help your doctor plan the best treatment.

Some cases of prostate cancer can be passed down from one generation to the next. Genetic counseling may be right for you. Learn more about the risk to you and your family on our genetic testing page.