How is prostate cancer diagnosed?
If you are having symptoms of prostate cancer or the result of a screening test raises concerns about cancer, you will need to see a doctor and probably have some tests.
Medical history and physical exam
If your doctor suspects you might have prostate cancer, you will be asked about any symptoms you are having, such as any urinary or sexual problems, and how long you have had them. Your doctor may also ask about bone pain, which could be a sign that the cancer might have spread to your bones.
Your doctor will also do a physical exam and will check other parts of your body to see if the cancer has spread.
PSA blood test
Prostate-specific antigen (PSA) is a substance made by the prostate gland. It is found in small amounts in the blood. Most healthy men have PSA levels below 4 (ng/mL). Although the risk of prostate cancer goes up as the PSA level goes up, other things besides prostate cancer can affect PSA levels.
The PSA blood test can be used in different situations:
- It can be used to screen for prostate cancer in men without symptoms.
- It is one of the first tests done in men who have symptoms that might be caused by prostate cancer.
- It can be useful if prostate cancer has already been found. It can help tell if the cancer probably is still just in the prostate gland. It’s also an important test for monitoring the cancer during and after treatment.
Transrectal ultrasound (TRUS)
For this test, a small probe about the width of a finger is placed in the rectum. It gives off sound waves, which enter the prostate and create echoes that are picked up by the probe. A computer turns the pattern of echoes into a black and white picture of the prostate.
The test often takes less than 10 minutes. You will feel some pressure when the probe is put in, but it is usually not painful.
This test can be used to look for tumors in the prostate. It is most often used during a prostate biopsy to guide the biopsy needles into the right area of the prostate. It is also used as a guide during some forms of treatment such as cryosurgery.
If certain symptoms or the results of tests like the PSA blood test and/or DRE suggest that you might have prostate cancer, your doctor will take samples of the prostate to see if cancer is present. This is called a prostate biopsy. Here is how it’s done:
Guided by ultrasound, the doctor puts a thin, hollow needle through the wall of the rectum into the prostate gland. When the needle is pulled out, it takes out a small piece of prostate tissue (called a core). This is done from 8 to18 times, but most doctors will take about 12 samples. Samples are often taken from different parts of the prostate. Ask your doctor how many samples will be taken.
Although the test sounds painful, it usually isn’t as bad as it sounds because each core is taken very quickly. The doctor can also numb the area ahead of time. You might want to ask your doctor about doing this.
The biopsy takes about 10 minutes and is usually done in the doctor’s office. You probably will be given antibiotics to take ahead of time and maybe afterward to reduce the chance of infection.
For a few days afterward you may notice some soreness in that area, blood in your urine, or light bleeding from the rectum. Many men also see some blood in their semen or have rust-colored semen, which can last for several weeks after the biopsy.
Cancer may only be in a small area of the prostate. Because of this, sometimes the biopsy will miss the cancer even when it is there. This is known as a false-negative result. If your biopsy doesn’t show cancer, but your doctor still strongly suspects cancer, you might need a repeat biopsy.
Grading the prostate cancer
The biopsy sample will be sent to a lab. A doctor there will look for cancer cells in the sample. If cancer is present, the sample will be graded, which can help predict how fast the cancer is likely to grow and spread.
Prostate cancers are graded based on how closely the cells in the sample look like normal prostate cells. Those that look very different from normal cells are likely to mean a cancer that grows faster.
The system used most often for grading prostate cancer is called the Gleason system. Samples from 2 areas of the prostate are each graded from 1 to 5, and the number grades are added to give a Gleason score or sum of between 2 and 10. Most biopsies have a Gleason score of at least 6. A higher score means the cells look less normal and the cancer is likely to grow more quickly. Ask your doctor to explain the grade of your cancer because it is an important factor in deciding on treatment.
Other things you may see on a biopsy report
The biopsy report tells you the grade of the cancer (if it is present), but it also often provides other information that may give a better idea of the scope of the cancer. These can include:
- The number of biopsy core samples that contain cancer (for example, “7 out of 12”)
- The amount of cancer in each of the cores (given as a percentage)
- Whether the cancer is on one side (left or right) of the prostate or both sides (bilateral)
Sometimes when the prostate cells are seen under the microscope, they don’t look like cancer, but they’re not quite normal, either. These results are often reported as suspicious. You might see terms on the biopsy report like:
- Prostatic intraepithelial neoplasia (PIN)
- Atypical small acinar proliferation (ASAP), or just atypia
- Proliferative inflammatory atrophy (PIA)
Your doctor can explain what these results might mean in your case. For more on how biopsy results are reported, see the “Prostate Pathology” section of our website.
Imaging tests to look for cancer spread
Imaging tests use x-rays, magnetic fields, sound waves, or radioactive substances to create pictures of the inside of your body. Men with a normal DRE result, a low PSA level, and a low Gleason score may not need any of these tests because the chance that the prostate cancer has spread is so low. Tests may be done, though, if the doctor suspects your cancer has spread. The imaging tests used most often for prostate cancer include:
If prostate cancer spreads to other parts of the body, it often goes to the bones first. A bone scan can show whether the cancer has reached the bones. e
For this test, a small amount of radioactive material is put into your vein (given IV). The dose of radiation is very low. The substance is drawn to damaged areas of bone throughout the body and shows up on the bone scan as “hot spots.” These places could be cancer, or they could be caused by arthritis or other bone diseases. To find out, more tests may be needed.
CT scan (computed tomography)
This test can sometimes tell if prostate cancer has spread into nearby lymph nodes. If your prostate cancer has come back after treatment, the CT scan can often tell if it is growing into other organs in your pelvis.
A CT scanner has been described as a large donut, with a narrow table that slides in and out of the middle opening. During the scan, a series of x-rays is taken from many angles while you lie on the table. A computer combines the pictures to give a detailed image.
For some scans, you might be asked to drink 1 or 2 pints of a contrast liquid before the test. You might also have a contrast dye put into your vein (given IV). A few people are allergic and get hives. Rarely, more serious problems, like trouble breathing or low blood pressure, can occur. Be sure to tell your doctor if you have any allergies or have ever had trouble with any contrast material used for x-rays.
MRI (magnetic resonance imaging)
This test is like a CT scan except that it uses radio waves and strong magnets instead of x-rays. The MRI gives a very clear picture to help the doctor see whether the cancer has spread from the prostate to other nearby structures. Because the scanners use magnets, people with pacemakers, certain heart valves, or other medical implants may not be able to get an MRI.
MRI scans take longer than CT scans – often up to an hour. During the scan you lie in a narrow tube which is confining and can be upsetting to some people. To get a better picture, many doctors will place a probe inside the rectum, which can be uncomfortable. Like CT scans, a contrast dye might be put into your vein, but this is done less often.
Like the bone scan, the ProstaScint scan uses an injection of low levels of a radioactive substance to find cancer that has spread beyond the prostate. But this substance is attracted to prostate cells instead of bone. You will be asked to lie on a table while a special camera takes pictures of your body. This is usually done about half an hour after the injection and again 3 to 5 days later.
This test isn’t often used for men who have just been diagnosed with prostate cancer, but it is sometimes used to look for cancer that may have come back after treatment.
Lymph node biopsy
In a lymph node biopsy, one or more lymph nodes are removed to see if they have cancer cells. If your cancer has spread to nearby lymph nodes, surgery to cure the cancer may not be an option, and you and your doctor will have to look at other treatment choices. Lymph node biopsies are rarely done unless your doctor is concerned that the cancer has spread. A lymph node biopsy might be done at different times:
- During surgery: The surgeon may remove lymph nodes in the pelvis during the same operation to remove the prostate gland.
- As a separate procedure: This is sometimes done when surgery isn’t going to be used to treat the cancer (such as for some men who choose radiation therapy). This type of biopsy can be done laparoscopically. The surgeon uses a long, thin tube with a small camera on the end to remove lymph nodes through a small cut. It can also be done as a fine needle aspiration (FNA), where a thin needle is placed through the skin and into lymph nodes to remove some cells.
Last Medical Review: 01/09/2015
Last Revised: 01/30/2015