Staging is the process of finding out how far the cancer has spread. The stage of a cancer is one of the most important factors in selecting treatment options.

Depending on the results of your physical exam and biopsy, the doctor may order certain imaging tests, such as a chest x-ray, mammograms, bone scans, computed tomography (CT) scans, magnetic resonance imaging (MRI) scans, and/or positron emission tomography (PET) scans (see below). Blood tests may also be done to evaluate your overall health and to help detect whether the cancer has spread to certain organs.

Imaging tests to look for breast cancer spread

Once breast cancer is diagnosed, one or more of the following tests may be done.

Chest x-ray

This test may be done to see whether the breast cancer has spread to the lungs.

Mammogram

If they haven't been done already, more extensive mammograms may be done to get more thorough views of the breasts.

Bone scan

A bone scan can help show if a cancer has metastasized (spread) to the bones. It can be more useful than standard x-rays because it can view all of the bones of the body at the same time.

For this test, a small amount of low-level radioactive material is injected into a vein (intravenously, or IV). The substance settles in areas of bone changes 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 changes appear as "hot spots" on your skeleton -- that is, they attract the radioactivity. These areas may suggest the presence of metastatic cancer, but arthritis or other bone diseases can also cause the same pattern. To distinguish 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.

Computed tomography (CT) scan

The CT scan is an x-ray test that produces detailed cross-sectional images of your body. Instead of taking one picture, like a regular x-ray, a CT scanner takes many pictures as it rotates around you while you lie on a table. A computer then combines these pictures into images of slices of the part of your body being studied. In people with breast cancer, this test is most often used to look at the chest and/or abdomen to see if the cancer has spread to other organs.

Prior to the CT scan, you may be asked to drink a contrast solution and/or receive an IV (intravenous) line through which a contrast dye is injected. This helps better outline structures in your body.

The contrast may cause some flushing (a feeling of warmth, especially in the face). Some people are allergic and get hives. Rarely, more serious reactions like trouble breathing or low blood pressure can occur. Be sure to tell the doctor if you have ever had a reaction to any contrast material used for x-rays.

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.

In recent years, spiral CT (also known as helical CT) has become available in many medical centers. This type of CT scan uses a faster machine. The scanner part of the machine rotates around the body continuously, allowing doctors to collect the images much more quickly than with standard CT. This lowers the chance of "blurred" images occurring as a result of breathing motion. It also lowers the dose of radiation received during the test. The biggest advantage may be that the "slices" it images are thinner, which yields more detailed pictures and allows doctors to look at suspicious areas from different angles.

CT guided needle biopsy: CT scans can also be used to precisely guide a biopsy needle into a suspected area of cancer spread. For this procedure, you remain on the CT scanning table while a radiologist advances a biopsy needle through the skin and toward the location of the mass. CT scans are repeated until the doctors are sure that the needle is within the mass. A fine needle biopsy sample (tiny fragment of tissue) or a core needle biopsy sample (a thin cylinder of tissue about ½-inch long and less than 1/8-inch in diameter) is then removed and sent to be looked at under a microscope.

Magnetic resonance imaging (MRI) scan

MRI scans can be used to look for cancer spread in various parts of the body, just like CT scans. MRI scans are particularly helpful in looking at the brain and spinal cord.

MRI scans use radio waves and strong magnets instead of x-rays. The energy from the radio waves is absorbed 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. A contrast material called gadolinium is often injected into a vein before the scan to better see details.

MRI scans are a little more uncomfortable than CT scans. First, they take longer -- often up to an hour. Second, you have to lie inside a narrow tube, which is confining and can upset people with claustrophobia (a fear of enclosed spaces). Newer, "open" MRI machines can sometimes help with this if needed. The machine also makes buzzing and clicking noises that you may find disturbing. Some centers provide headphones with music to block this out.

Ultrasound

Ultrasound uses sound waves and their echoes to produce a picture of internal organs or masses. A small microphone-like instrument called a transducer emits sound waves and picks up the echoes as they bounce off body tissues. The echoes are converted by a computer into a black and white image that is displayed on a computer screen. This test is painless and does not expose you to radiation.

Abdominal ultrasound can be used to look for tumors in your liver or other abdominal organs. When you have an abdominal ultrasound exam, you simply lie on a table and a technician moves the transducer over the skin overlying the part of your body being examined. Usually, the skin is first lubricated with gel.

Positron emission tomography (PET) scan

PET scans involve injecting glucose (a form of sugar) that contains a radioactive atom into the blood. Because cancer cells in the body are growing rapidly, they absorb large amounts of the radioactive sugar. After about an hour, a special camera is used to create a picture of areas of radioactivity in the body.

PET is useful when your doctor thinks the cancer may have spread but doesn't know where. The picture is not finely detailed like a CT or MRI scan, but it provides helpful information about your whole body. Some newer machines are able to perform both a PET and CT scan at the same time (PET/CT scan). This allows the radiologist to compare areas of higher radioactivity on the PET with the appearance of that area on the CT.

This test can be used along with a mammogram, especially when looking for cancer in axillary lymph nodes. So far, most studies show it isn't very sensitive in finding small deposits of cancer in lymph nodes, although it can find big ones.

The American Joint Committee on Cancer (AJCC) TNM system

A staging system is a standardized way for the cancer care team to summarize information about how far a cancer has spread. The most common system used to describe the stages of breast cancer is the American Joint Committee on Cancer (AJCC) TNM system.

The stage of a breast cancer can be based either on the results of physical exam, biopsy, and imaging tests (called the clinical stage), or on the results of these tests plus the results of surgery (called the pathologic stage). The staging described here is the pathologic stage, which includes the findings after surgery, when the pathologist has looked at the breast mass and removed lymph nodes. Pathologic staging is likely to be more accurate than clinical staging, as it allows the doctor to get a firsthand impression of the extent of the cancer.

The TNM staging system classifies cancers based on their T, N, and M stages:

• T stands for tumor (its size and how far it has spread within the breast and to nearby organs).

• N stands for spread to lymph nodes (bean-shaped collections of immune system cells that help fight infections and cancers).

• M is for metastasis (spread to distant organs).

Additional letters or numbers appear after T, N, and M to provide more details about the tumor, lymph nodes, and metastasis:

• The letter T followed by a number from 0 to 4 describes the tumor's size and spread to the skin or to the chest wall under the breast. Higher T numbers indicate a larger tumor and/or wider spread to tissues near the breast.

• The letter N followed by a number from 0 to 3 indicates whether the cancer has spread to lymph nodes near the breast and, if so, how many lymph nodes are affected.

• The letter M followed by a 0 or 1 indicates whether the cancer has spread to distant organs -- for example, the lungs or bones.

Breast cancer T, N, and M categories

Primary tumor (T):

TX: Primary tumor cannot be assessed.
T0: No evidence of primary tumor.
Tis: Carcinoma in situ (DCIS or Paget disease of the nipple with no associated tumor mass)
T1: Tumor is 2 cm (3/4 of an inch) or less across.
T2: Tumor is more than 2 cm but not more than 5 cm (2 inches) across.
T3: Tumor is more than 5 cm across.
T4: Tumor of any size growing into the chest wall or skin.

Nearby lymph nodes (N) (based on looking at them under a microscope):

• Cancer has spread to 10 or more axillary lymph nodes.
• Cancer has spread to the lymph nodes under the clavicle (collar bone).
• Cancer has spread to the lymph nodes above the clavicle.
• Cancer involves axillary lymph nodes and has enlarged the internal mammary lymph nodes.
• Cancer involves 4 or more axillary lymph nodes, and tiny amounts of cancer are found in internal mammary lymph nodes on sentinel lymph node biopsy.

Metastasis (M):

MX: Presence of distant spread (metastasis) cannot be assessed.
M0: No distant spread.
M1: Spread to distant organs is present. (The most common sites are bone, lung, brain, and liver.)

Breast cancer stage grouping

Once the T, N, and M categories have been determined, this information is combined in a process called stage grouping. Cancers with similar stages tend to have a similar outlook and thus are often treated in a similar way. Stage is expressed in Roman numerals from stage I (the least advanced stage) to stage IV (the most advanced stage). Non-invasive cancer is listed as stage 0.

Stage 0: Tis, N0, M0: This is ductal carcinoma in situ (DCIS), the earliest form of breast cancer. In DCIS, cancer cells are still within a duct and have not invaded deeper into the surrounding fatty breast tissue. Paget disease of the nipple (without an underlying tumor mass) is also stage 0. In all cases the cancer has not spread to lymph nodes or distant sites.

Stage I: T1, N0, M0: The tumor is 2 cm (about 3/4 of an inch) or less across and has not spread to lymph nodes or distant sites.

Stage IIA: T0, N1, M0 / T1, N1, M0 / T2, N0, M0: One of the following applies:

• The tumor is 2 cm or less across (or is not found) and has spread to 1 to 3 axillary lymph nodes.

• The tumor is 2 cm or less across (or is not found) and tiny amounts of cancer are found in internal mammary lymph nodes on sentinel lymph node biopsy.

• The tumor is 2 cm or less across (or is not found), has spread to 1 to 3 axillary lymph nodes, and tiny amounts of cancer are found in internal mammary lymph nodes on sentinel lymph node biopsy.

• The tumor is larger than 2 cm across and less than 5 cm but hasn't spread to the lymph nodes.

In all cases, the cancer hasn't spread to distant sites.

Stage IIB: T2, N1, M0 / T3, N0, M0: One of the following applies:

• The tumor is larger than 2 cm and less than 5 cm across. It has spread to 1 to 3 axillary lymph nodes and/or tiny amounts of cancer are found in internal mammary lymph nodes on sentinel lymph node biopsy.

• The tumor is larger than 5 cm across but does not grow into the chest wall or skin and has not spread to lymph nodes.

The cancer hasn't spread to distant sites.

Stage IIIA: T0-2, N2, M0 / T3, N1-2, M0: One of the following applies:

• The tumor is not more than 5 cm across (or cannot be found). It has spread to 4 to 9 axillary lymph nodes, or it has enlarged the internal mammary lymph nodes.
• The tumor is larger than 5 cm across but does not grow into the chest wall or skin. It has spread to 1 to 9 axillary nodes, or to internal mammary nodes.

In all cases, the cancer hasn't spread to distant sites.

Stage IIIB: T4, N0-2, M0: The tumor has grown into the chest wall or skin, and one of the following applies:

• It has not spread to the lymph nodes.
• It has spread to 1 to 3 axillary lymph nodes and/or tiny amounts of cancer are found in internal mammary lymph nodes on sentinel lymph node biopsy.
• It has spread to 4 to 9 axillary lymph nodes, or it has enlarged the internal mammary lymph nodes.

The cancer hasn't spread to distant sites.

Stage IIIC: T0-4, N3, M0: The tumor is any size (or can't be found), and one of the following applies:

• Cancer has spread to 10 or more axillary lymph nodes.
• Cancer has spread to the lymph nodes under the clavicle (collar bone).
• Cancer has spread to the lymph nodes above the clavicle.
• Cancer involves axillary lymph nodes and has enlarged the internal mammary lymph nodes.
• Cancer involves 4 or more axillary lymph nodes, and tiny amounts of cancer are found in internal mammary lymph nodes on sentinel lymph node biopsy.

The cancer hasn't spread to distant sites.

Stage IV: T0-4, N0-3, M1: The cancer can be any size and may or may not have spread to nearby lymph nodes. It has spread to distant organs (the most common sites are the bone, liver, brain, or lung), or to lymph nodes far from the breast.

If you have any questions about the stage of your cancer and what it might mean in your case, be sure to ask your doctor.

Breast cancer survival rates by stage

The numbers below come from the National Cancer Institute's Surveillance Epidemiology and End Results (SEER) database. There are some important points to note about these numbers:

• The 5-year survival rate refers to the percentage of patients who live at least 5 years after being diagnosed with cancer. Many of these patients live much longer than 5 years after diagnosis. Five-year relative survival rates (such as the numbers below) compare the observed survival of people with cancer with that expected for people without cancer. That means that relative survival reflects the impact of cancer, but not other diseases, on survival. This is why relative survival rates are considered to be a more accurate way to describe the outlook for patients with a particular type and stage of cancer.

• While these numbers are among the most current we have available, they represent people who were first diagnosed and treated many years ago. Improvements in treatment since then mean that the survival rates for people now being diagnosed with these cancers may be higher.

• Survival statistics can sometimes be useful as a general guide, but they may not accurately represent any one person's prognosis. A number of other factors, including other tumor characteristics and a person's age and general health, can also affect outlook. Your doctor is likely to be a good source as to whether these numbers may apply to you, as he or she is familiar with the aspects of your particular situation.

Last Medical Review: 09/24/2008
Last Revised: 09/24/2008