The stage (extent) of a cancer is one of the most important factors in choosing treatment options and predicting a patient's outlook. If your prostate biopsy confirms that you have cancer, more tests may be done to find out how far it has spread within the prostate, to nearby tissues, or to other parts of the body. This process is called staging.

Your doctor will use your digital rectal exam (DRE) results, prostate-specific antigen (PSA) level, and Gleason score to figure out how likely it is that your cancer has spread outside of the prostate. This information is used to decide which other tests (if any) need to be done before deciding on a treatment. Men with a normal DRE result, a low PSA, and a low Gleason score may not need any other tests because the chance that the cancer has spread is so low.

Medical history and physical exam

The physical exam, especially the digital rectal exam (DRE), is an important part of prostate cancer staging. By doing a DRE your doctor can sometimes tell whether the cancer is only on one side of the prostate, whether it is present on both sides, or whether it is likely to have spread beyond the prostate gland to nearby tissues. The DRE is always used together with the PSA blood test for early detection of prostate cancer and is discussed in the section, "Can prostate cancer be found early?" Your doctor may also examine other areas of your body to see whether the cancer has spread.

Your doctor will also ask you about symptoms such as urinary problems or bone pain, which could suggest that the cancer may have spread to your bones.

Imaging tests used for prostate cancer staging

Not all men with prostate cancer need to have imaging tests, but for those who do, the following tests are sometimes used.

Radionuclide bone scan

When prostate cancer spreads to distant sites, it often goes to the bones first. (Even when prostate cancer spreads to the bone, it is still called prostate cancer, not bone cancer.) A bone scan can help show whether cancer has reached the bones.

For this test, a small amount of low-level radioactive material is injected into a vein (intravenously, or IV). The substance settles in damaged bone tissue throughout the entire skeleton over the course of a couple of hours. You then lie on a table for about 30 minutes while a special camera detects the radioactivity and creates a picture of your skeleton.

Areas of bone damage appear as "hot spots" on your skeleton -- that is, they attract the radioactivity. Hot spots may suggest the presence of metastatic cancer, but arthritis or other bone diseases can also cause the same pattern. To tell the difference between these conditions, your cancer care team may use other imaging tests such as simple x-rays or CT or MRI scans to get a better look at the areas that light up, or they may even take biopsy samples of the bone.

The injection is the only uncomfortable part of the scanning procedure. The radioactive material is passed out of the body in the urine over the next few days. The amount of radioactivity used is very low, so it carries very little risk to you or others. But you still may want to ask your doctor if you should take any special precautions after having this test.

Computed tomography (CT)

The CT scan (also known as a CAT scan) is a special kind of x-ray that gives detailed, cross-sectional images of your body. Instead of taking one picture, like a standard x-ray, a CT scanner takes many pictures of the part of your body being studied as it rotates around you. A computer then combines these pictures into images of slices of the part of your body being studied.

Before the first set of pictures is taken you may be asked to drink 1 or 2 pints of "oral contrast." This helps outline the intestine so that it looks different from any tumors. You may also receive an IV (intravenous) line through which a different kind of contrast is injected. This helps better outline structures in your body. You will also need to drink enough liquid to have a full bladder. This will keep the bowel away from the area of the prostate gland.

The IV contrast can cause your body to feel flushed (a feeling of warmth with some redness of the skin). A few people are allergic and get hives. Rarely, more serious reactions, like trouble breathing or low blood pressure, can occur. Medication can be given to prevent and treat allergic reactions, so be sure to tell your doctor if you have ever had a reaction to any contrast material used for x-rays. It is also important to let your doctor know about any other allergies.

CT scans take longer than regular x-rays. You need to lie still on a table while they are being done. During the test, the table moves in and out of the scanner, a ring-shaped machine that completely surrounds the table. You might feel a bit confined by the ring you have to lie in while the pictures are being taken.

This test can help 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 or structures in your pelvis. On the other hand, CT scans rarely provide useful information about newly diagnosed prostate cancers that are likely to be confined to the prostate based on other findings (DRE result, PSA level, and Gleason score). CT scans are not as useful as magnetic resonance imaging (MRI) for looking at the prostate gland itself.

Magnetic resonance imaging (MRI)

MRI scans use radio waves and strong magnets instead of x-rays. The energy from the radio waves is absorbed by the body and then released in a pattern formed by the type of body tissue and by certain diseases. A computer translates the pattern into a very detailed image of parts of the body. This produces cross-sectional slices of the body like a CT scanner, but it can also show slices (views) from several angles. As with a CT scan, a contrast material might be injected, but this is done less often.

MRI scans can be very helpful in looking at prostate cancer. They can produce a very clear picture of the prostate and show whether the cancer has spread outside the prostate into the seminal vesicles or the bladder. This information can be very important for your doctors in planning your treatment. But like CT scans, they may not provide useful information about newly diagnosed prostate cancers that are likely to be localized (confined to the prostate) based on other factors.

MRI scans take longer than CT scans -- often up to an hour. During the scan, you need to lie still inside a narrow tube, which is confining and can upset people who don't like enclosed spaces. The machine also makes clicking and buzzing noises. Some places provide headphones with music to block this out. To improve the accuracy of the MRI, many doctors will place a probe, called an endorectal coil, inside your rectum. This must stay in place for 30 to 45 minutes and can be uncomfortable.

ProstaScint^TM scan

Like the bone scan, the ProstaScint scan uses an injection of low-level radioactive material to find cancer that has spread beyond the prostate. Both tests look for areas of the body where the radioactive material collects, but they work in different ways.

While the radioactive material used for the bone scan is attracted to bone, the material for the ProstaScint scan is attracted to prostate cells in the body. It is attached to a monoclonal antibody, a type of man-made protein that recognizes and sticks to a particular substance. In this case, the antibody sticks to prostate-specific membrane antigen (PSMA), a substance found at high levels in normal and cancerous prostate cells.

After the material is injected, you will be asked to lie on a table while a special camera creates an image of the body. This is usually done about half an hour after the injection and again 3 to 5 days later.

The advantage of this test is that it can find prostate cancer cells in lymph nodes and other soft (non-bone) organs. Because the antibody only sticks to prostate cancer cells, other cancers or benign problems should not cause abnormal results. But the test is not always accurate, and the results can sometimes be confusing.

Most doctors do not recommend this test for men who have just been diagnosed with prostate cancer. But it may be useful after treatment if your blood PSA level begins to rise and other tests are not able to find the exact location of your cancer. Doctors may not order this test if they believe it will not be helpful for a given patient.

Lymph node biopsy

In a lymph node biopsy, one or more lymph nodes are removed to see if they contain cancer cells. This procedure, also called a lymph node dissection or lymphadenectomy, is sometimes done to find out whether the cancer has spread from the prostate to nearby lymph nodes. If cancer cells are found in a lymph node, surgery is not likely to cure the cancer, so other treatment options are considered. Lymph node biopsies are rarely done unless your doctor is concerned that the cancer has spread. There are several ways to biopsy lymph nodes.

Surgical biopsy

The surgeon may remove lymph nodes through an incision in the lower part of your abdomen. This is often done in the same operation as the radical prostatectomy. (See the section, "How is prostate cancer treated?" for information about radical prostatectomy.)

If the surgeon has a reason to suspect that the cancer may have spread (such as a PSA level over 20 or a Gleason score over 7), he or she may remove some lymph nodes before attempting to remove the prostate gland. A pathologist then looks at the nodes while you are still under anesthesia to help the surgeon decide whether to continue with the radical prostatectomy. This is called a frozen section exam because the tissue sample is frozen before thin slices are taken to check under a microscope. If the nodes contain cancer, the operation is usually stopped (and the prostate is left in place). This is because removing the prostate would be unlikely to cure the cancer, and it could still result in serious complications or side effects.

If the PSA is less than 20 and the Gleason score isn't high, the chance that the cancer has already spread is low. In that case, surgeons do not often request a frozen section exam and instead the lymph nodes are sent to be looked at along with the removed prostate gland. The test results are usually available 3 to 7 days after surgery.

Laparoscopic biopsy

A laparoscope is a long, slender tube with a small video camera on the end that is inserted into the abdomen to let the surgeon see inside without making a large incision. Other small incisions are made to insert long instruments to remove the lymph nodes. The surgeon removes all of the lymph nodes around the prostate gland and sends them to the pathologist. Because there are no large incisions, most people recover fully in only 1 or 2 days, and the operation leaves very small scars. This procedure is not common, but it is sometimes used when it's important to know the lymph node status and radical prostatectomy is not planned (such as for certain men who choose treatment with radiation therapy).

Fine needle aspiration (FNA)

If your lymph nodes appear enlarged on an imaging study (CT or MRI) a specially trained radiologist may take a sample of cells from an enlarged lymph node by using a technique called fine needle aspiration (FNA). To do this, the doctor uses the CT scan image to guide a long, thin needle through the skin in the lower abdomen and into an enlarged lymph node. A syringe attached to the needle allows the doctor to take a small tissue sample from the node. Before the needle is placed, your skin will be numbed with local anesthesia. You will be able to return home a few hours after the procedure. This method is not used very often.

The AJCC TNM staging system

A staging system is a standard way in which the cancer care team describes the extent to which a cancer has spread. While there are several different staging systems for prostate cancer, the most widely used system is the American Joint Committee on Cancer (AJCC) TNM System.

The TNM System describes:

• the extent of the primary tumor (T category)
• whether the cancer has spread to nearby lymph nodes (N category)
• the absence or presence of distant metastasis (M category)

The overall stage takes all 3 categories into account, along with the Gleason score (described in the section, "How is prostate cancer diagnosed?").

There are actually 2 types of staging for prostate cancer. The clinical stage is your doctor's best estimate of the extent of your disease, based on the results of the physical exam (including DRE), lab tests, prostate biopsy, and any imaging studies you have had.

If you have surgery, your doctors can also determine the pathologic stage, which is based on the surgery and examination of the removed tissue. This means that if you have surgery, the stage of your cancer might actually change afterward (if cancer was found in a place it wasn't suspected, for example). Pathologic staging is likely to be more accurate than clinical staging, as it allows your doctor to get a firsthand impression of the extent of your disease. This is one possible advantage of having surgery (radical prostatectomy) as opposed to radiation therapy or watchful waiting (expectant management).

Both types of staging use the same categories (although the T1 category is not used in pathologic staging).

T categories

There are 4 categories for describing the local extent of the prostate tumor, ranging from T1 to T4. Most of these have subcategories as well.

T1: Your doctor can't feel the tumor or see it with imaging such as transrectal ultrasound.

T1a: The cancer is found incidentally (by accident) during a transurethral resection of the prostate (often abbreviated as TURP) that was done for benign prostatic hyperplasia (BPH). Cancer is present in less than 5% of the tissue removed.

T1b: The cancer is found during a TURP but is present in more than 5% of the tissue removed.

T1c: The cancer is found by needle biopsy that was done because of an increased PSA.

T2: Your doctor can feel the cancer when a digital rectal exam (DRE) is done, but it still appears to be confined to the prostate gland.

T2a: The cancer is in one half or less of only one side (left or right) of your prostate.

T2b: The cancer is in more than half of only one side (left or right) of your prostate.

T2c: The cancer is in both sides of your prostate.

T3: The cancer has begun to grow and spread outside your prostate and may involve the seminal vesicles.

T3a: The cancer extends outside the prostate but not to the seminal vesicles.

T3b: The cancer has spread to the seminal vesicles.

T4: The cancer has grown into tissues next to your prostate (other than the seminal vesicles), such as the bladder sphincter (muscle that helps control urination), the rectum, and/or the wall of the pelvis.

N categories

N0: The cancer has not spread to any lymph nodes.

N1: The cancer has spread to one or more regional (nearby) lymph nodes in the pelvis.

M categories

M0: The cancer has not spread beyond the regional lymph nodes.

M1: The cancer has spread beyond the regional nodes.

M1a: The cancer has spread to distant (outside of the pelvis) lymph nodes.

M1b: The cancer has spread to the bones.

M1c: The cancer has spread to other organs such as lungs, liver, or brain (with or without bone disease).

Stage groupings

Once the T, N, and M categories have been determined, this information is combined, along with the Gleason score, in a process called stage grouping. The overall stage is expressed in Roman numerals from I (the least advanced) to IV (the most advanced). This is done to help determine treatment options and the outlook for survival or cure.

Stage I : T1a, N0, M0, low Gleason score (2 to 4)

The cancer is still within the prostate and has not spread to lymph nodes or elsewhere in the body. The cancer was found during a transurethral resection, it had a low Gleason score (2 to 4), and less than 5% of the tissue was cancerous.

Stage II: T1a, N0, M0, Gleason score of 5 to 10; OR T1b-T2, N0, M0, any Gleason score

The cancer is still within the prostate and has not spread to the lymph nodes or elsewhere in the body, and one of the following applies:

• It was found during a transurethral resection, was less than 5% of the tissue removed [T1a], and has an intermediate or high Gleason score (5 or higher), 

• It was found during a transurethral resection and more than 5% of the tissue contained cancer [T1b]; or

• It was discovered because of a high PSA level, cannot be felt on digital rectal exam or seen on transrectal ultrasound, and was diagnosed by needle biopsy [T1c]; or

• It can be felt on digital rectal exam or seen on transrectal ultrasound [T2].

Stage III: T3, N0, M0, any Gleason score (2 to 10)

The cancer has begun to spread outside the prostate and may have spread to the seminal vesicles, but it has not spread to the lymph nodes or elsewhere in the body.

Stage IV: T4, N0, M0;OR any T, N1, M0;OR any T, any N, M1 (any Gleason score)

One or more of the following apply:

• The cancer has spread to tissues next to the prostate (other than the seminal vesicles), such as the bladder's external sphincter (muscle that helps control urination), rectum, and/or the wall of the pelvis (T4); and/or

• It has spread to the lymph nodes (N1); and/or

• It has spread to other, more distant sites in the body (M1).

In addition to the TNM system, other systems have been used to stage prostate cancer. The Whitmore-Jewett system, which stages prostate cancer as A, B, C, or D, was commonly used in the past, but most prostate specialists now use the TNM system. If your doctors use this system, ask them to translate it into the TNM system or to explain how their staging will determine your treatment options.

5-year relative survival rates by stage

The National Cancer Institute (NCI) maintains a large national database on survival statistics for different types of cancer. This database does not group cancers by AJCC stage, but instead groups cancers into local, regional and distant stages.

Local stage means that there is no sign that the cancer has spread outside of the prostate. This corresponds to AJCC stages I and II. Almost 9 out of 10 prostate cancers are found in this early stage. If the cancer has spread from the prostate to nearby areas, it is called regional disease. This includes cancers that are T3 or T4, and cancers that have spread to nearby lymph nodes (N1), as long as the cancer hasn't spread to distant parts of the body (M0). Distant stage includes all cancers that have spread to distant lymph nodes, bone, or other organs (M1).

5-year relative survival by stage at the time of diagnosis

The 5-year survival rate refers to the percentage of patients who live at least 5 years after their cancer is diagnosed. These rates are used to create a standard way of discussing prognosis (outlook). Of course, many of these patients live much longer than 5 years after diagnosis. Five-year relative survival rates compare the observed survival with that expected for people without the cancer. That means that relative survival only talks about deaths from the cancer in question. This is a more accurate way to describe the outlook for patients with a certain cancer. Five-year survival rates are based on patients diagnosed and first treated more than 5 years ago. Improvements in treatment since then may result in a better outlook for recently diagnosed patients.

Last Medical Review: 10/29/2008
Last Revised: 08/25/2008