The experts 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.
Prostate Cancer Diagnosis
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 that might signal cancer or pre-cancerous conditions.
Although this test usually is not as reliable as the PSA blood test, a DRE may be able to find cancer if a man has 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, expressed in nanograms per milliliter (ng/mL). This level is used to assess prostate cancer risk. A higher PSA level usually means a higher chance of having prostate cancer.
However, the test has limitations. PSA is produced by both prostate tissue and prostate cancer. Sometimes prostate cancer does not produce much PSA and higher levels can be caused by factors other than cancer, including:
- 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
On the other hand, 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
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. However, 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.
Additional PSA Testing
Besides screening, PSA testing can be used in other ways in men who have been diagnosed with prostate cancer. For instance, it may:
- Help doctors plan your 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
If your doctor suspects prostate cancer, a biopsy may be performed. This is the only way to tell for sure if you have prostate cancer.
Biopsies for prostate cancer are done in a doctor’s office or other facility as an outpatient procedure. A local anesthetic like dentists use, often lidocaine, is injected into the area close to the prostate to make the procedure more comfortable.
A small transrectal ultrasound (TRUS) probe with an imaging device is inserted into the rectum so the doctor can 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.
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.
Some people have an elevated risk of developing prostate cancer. Review the prostate cancer screening guidelines to see if you need to be tested.
In rare cases, prostate cancer can be passed down from one generation to the next. Genetic counseling may be right for you. Visit our genetic testing page to learn more.
If you are diagnosed with prostate cancer, your doctor will make a series of estimates about the risk the disease may be harmful in the future. Factors include:
- Gleason score (see below)
- PSA level
- Clinical stage, which is based on findings of the digital rectal exam (DRE)
- 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/nL
- Gleason score of 6 or lower
- No tumor felt on DRE or feels contained within the prostate gland with only a small abnormal area
- 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
- Tumor can be felt on one or both sides of the prostate on DRE, but it seems to be contained within the gland
- Aggressive features that increase the chance of spreading now or in the future
- PSA over 20 ng/mL
- Gleason score of 8 to10
- Tumor can be felt on DRE and seems to have spread outside the gland
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.
Prostate cancer contains several types of cells. The Gleason system uses the numbers 1 to 5 to grade the most common (primary) and next most common (secondary) cell types found in a tissue sample. The sum of these two numbers is the Gleason score, which indicates how aggressive the tumor is. The higher the Gleason score, the more aggressive the cancer.
Gleason grades 1 and 2 are rarely seen since these changes are now usually classified as benign or occur at the center of the gland and remain undiscovered. That means the usual lowest grade is 3. Gleason scores of:
- 3+3 are low grade and have the lowest risk of harm
- 3+4 and 4+3 are intermediate risk — the latter being the more aggressive type
- 4+4 through 5+5 are the highest risk
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.