How is prostate cancer diagnosed?
If you are having symptoms of prostate cancer or the result of a screening test is concerning for cancer, you will need to see a doctor and get some tests.
Medical history and physical exam
If your doctor suspects you might have prostate cancer, he or she will ask you 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 high concentrations in semen, and in smaller amounts in the blood. Most healthy men have 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 is one of the first tests done in men who have symptoms that might be caused by prostate cancer.
The PSA test can also be useful if prostate cancer has already been found.
Transrectal ultrasound (TRUS) uses sound waves to make a picture of the prostate. For this test, a small probe 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. The TRUS probe is about the width of a finger and is lubricated before it is placed in your rectum. You will feel some pressure when it 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 (discussed later in this document).
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 take samples of prostate tissue to see if cancer is present. This is called a prostate biopsy.
A core needle biopsy is the type of biopsy used most often. Here is how it's done:
Guided by TRUS, 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 will likely be given antibiotics to take ahead of time and maybe afterwards to reduce the chance of infection. For a few days afterwards you may notice some soreness, 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 present 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, a repeat biopsy may be needed.
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. Grading the cancer helps to predict how fast the cancer is likely to grow and spread.
Prostate cancers are graded on the basis of 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 making treatment decisions.
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. Your doctor can explain what these results might mean in your case.
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 early stage prostate cancer don’t usually need these tests. They 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 distant places, it often goes to the bones first. (Even when this happens, it is still prostate cancer, not bone cancer.) A bone scan is done to show whether the cancer has spread from the prostate gland to bones.
For this test, a radioactive material is put into your vein (given IV). The dose of radiation is very low. The radioactive 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 need to be done.
CT scan (computed tomography)
This test can sometimes tell whether prostate cancer has spread into nearby lymph nodes. If your prostate cancer has come back after treatment, the CT scan can often tell whether it is growing into other organs in your pelvis. CT scans are not as useful as MRIs for looking at the prostate gland itself.
A CT (also known as a CAT scan) is a special type of x-ray. A series of pictures is taken from many angles. A computer combines the pictures to give a detailed image. For some scans, you may be asked to drink 1 or 2 pints of a liquid that outlines the intestine so that it looks different from any tumors. You might also have a harmless 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.
A CT scan can help tell if your prostate cancer has spread into lymph nodes in your pelvis. (Lymph nodes are a network of bean-sized collections of white blood cells that fight infection.) CT scans take longer than regular x-rays. You need to lie still on a table inside a ring-shaped machine. You might feel a bit confined by the ring you have to lie in while the pictures are being taken.
MRI (magnetic resonance imaging)
This test is like a CT scan except that it uses radio waves and strong magnets instead of x-rays to make the pictures. The MRI gives a very clear picture to help the doctor see whether the cancer has spread to the seminal vesicles or 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 upset some people. In order to get a better picture, many doctors will place a probe inside the rectum. It must stay in place for 30 to 45 minutes and 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 low levels of a radioactive substance to find cancer that has spread beyond the prostate. The difference is that while the bone scan can find areas of cancer in bones, this test can find the spread of prostate cancer to lymph nodes and other organs.
The radioactive substance is put into your vein and is drawn to prostate cells anywhere in the body. 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 contain cancer cells. If your cancer has spread to nearby lymph nodes, surgery to cure the cancer may not be an option and the doctor will look at other treatment choices. Lymph node biopsies are rarely done unless your doctor is concerned that the cancer has spread. There are different types of biopsies:
- Surgical biopsy: where the surgeon removes lymph nodes through a cut (incision) in the lower part of the belly (abdomen)
- Laparoscopy: where the surgeon uses a laparoscope (a long, thin tube with a small camera on the end) to remove lymph nodes through a small cut (incision)
- Fine needle aspiration (FNA): where a thin needle is placed through the skin and into lymph nodes to remove a sample of cells. This may be done if a CT or MRI scan shows that lymph nodes near the prostate seem to be swollen.
Last Medical Review: 08/27/2013
Last Revised: 02/25/2014