The stage describes the extent of the cancer in the body. It is based on whether the cancer is invasive or non-invasive, the size of the tumor, how many lymph nodes are involved, and if it has spread to other parts of the body. The stage of a cancer is one of the most important factors in determining prognosis and treatment options.

Staging is the process of finding out how widespread a cancer is when it is diagnosed. Depending on the results of your physical exam and biopsy, your doctor may want you to have certain imaging tests such as a chest x-ray, mammograms of both breasts, bone scans, computed tomography (CT) scans, magnetic resonance imaging (MRI), and/or positron emission tomography (PET) scans (see below). Blood tests may also be done to evaluate your overall health and help find out if the cancer has spread to certain organs.

Imaging tests that 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 your lungs.

Mammogram

If they haven't been done already, more extensive mammograms may be done to get more thorough views of the breasts. This is to check for any other abnormal areas that could be cancer as well. This test is described in the section "How is breast cancer diagnosed?"

Bone scan

A bone scan can help show whether a cancer has spread (metastasized) to your bones. It can be more useful than standard x-rays because it can show 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 women 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.

Before any pictures are taken, you may be asked to drink 1 to 2 pints of a liquid called oral contrast. This helps outline the intestine so that certain areas are not mistaken for tumors. You may also receive an IV (intravenous) line through which a different kind of contrast dye (IV contrast) is injected. This helps better outline structures in your body.

The injection might 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. Medicine can be given to prevent and treat allergic reactions. 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.

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

This test is described in the sections "Can breast cancer be found early?" and "How is breast cancer diagnosed?" as an imaging test of the breast. It may be used to examine the breast with cancer, to look for other tumors. It may also be used to look at the opposite breast, to be sure that it does not contain any tumors. It is not yet clear how helpful this is in planning surgery in someone known to have breast cancer.

MRI scans are also used to look for cancer that has spread to 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 very 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 noise out.

Ultrasound

This test is described in the section "How is breast cancer diagnosed?" as an imaging test of the breast. But ultrasound can also be used to look for cancer that has spread to some other parts of the body.

Ultrasound tests use sound waves and their echoes to produce a picture of internal organs or masses. A small microphone-like instrument called a transducer sends out 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 shown 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

For a PET scan, glucose (a form of sugar) that contains a radioactive atom is injected into the bloodstream. 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.

A PET scan 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 do 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.

So far, most studies show it isn't very helpful in most cases of breast cancer, although it may be used when the cancer is known to have spread.

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 nearby 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).

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

Additional letters or numbers appear after T, N, and M to give 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 mean 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):

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

Lymph node staging for breast cancer has changed over time as technology has evolved. Earlier methods were useful in finding large deposits of cancer cells in the lymph nodes, but could miss microscopic areas of cancer spread. Over time, newer methods have made it possible to find smaller and smaller deposits of cancer cells. Experts haven't been sure what to do with the new information. Do tiny deposits of cancer cells affect outlook the same way that larger deposits do? How much cancer in the lymph node is needed to see a change in outlook or treatment?

These questions are still being studied, but for now, a deposit of cancer cells must contain at least 200 cells or be at least 0.2 mm across (less than 1/100 of an inch) for it to change the N stage. An area of cancer spread that is smaller than 0.2 mm (or less than 200 cells) doesn't change the stage, but is recorded with abbreviations that reflect the way the cancer spread was detected. The abbreviation "i+" means that cancer cells were only seen when a special stain, called immunohistochemistry, was used. The abbreviation "mol+" is used if the cancer could only be found using a technique called PCR. These very tiny areas are sometimes called isolated tumor cells. If the area of cancer spread is at least 0.2 mm (or 200 cells), but still not larger than 2 mm, it is called a micrometastasis (one mm is about the size of the width of a grain of rice). Micrometastases are counted only if there aren't any larger areas of cancer spread. Areas of cancer spread larger than 2 mm are known to affect outlook and do change the N stage. These larger areas are sometimes called macrometastases, but may just be called metastases.

Metastasis (M):

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. Lobular carcinoma in situ (LCIS) is sometimes also classified as stage 0 breast cancer, but most oncologists believe it is not a true breast cancer. In LCIS, abnormal cells grow within the lobules or milk-producing glands, but they do not penetrate through the wall of these lobules. 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 IA: 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 IB: T0 or T1, N1mi, M0: The tumor is 2 cm or less across (or is not found) with micrometastases in 1 to 3 axillary lymph nodes (the cancer in the lymph nodes is greater than 0.2mm across and/or more than 200 cells but is not larger than 2 mm). The cancer has not spread to distant sites.

Stage IIA: T0 or T1, N1 (but not N1mi), M0 / T2, N0, M0: One of the following applies:

• The tumor is 2 cm or less across (or is not found) (T1 or T0) and has spread to 1 to 3 axillary lymph nodes, with the cancer in the lymph nodes larger than 2 mm across (N1a).

• The tumor is 2 cm or less across (or is not found) (T1 or T0) and tiny amounts of cancer are found in internal mammary lymph nodes on sentinel lymph node biopsy (N1b).

• The tumor is 2 cm or less across (or is not found) (T1 or T0) and has spread to 1 to 3 lymph nodes under the arm and to internal mammary lymph nodes (found on sentinel lymph node biopsy) (N1c).

• The tumor is larger than 2 cm across and less than 5 cm (T2) but hasn't spread to the lymph nodes (N0).

The cancer hasn't spread to distant sites (M0).

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 (T2, N1).

• 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 (T3, N0).

The cancer hasn't spread to distant sites (M0).

Stage IIIA: T0 to T2, N2, M0 / T3, N1 or N2, 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 (T0 to T2, N2).

• 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 (T3, N1 or N2).

The cancer hasn't spread to distant sites (M0).

Stage IIIB: T4, N0 to N2, M0: The tumor has grown into the chest wall or skin (T4), and one of the following applies:

• It has not spread to the lymph nodes (N0).

• 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 (N1).

• It has spread to 4 to 9 axillary lymph nodes, or it has enlarged the internal mammary lymph nodes (N2).

The cancer hasn't spread to distant sites (M0).

Inflammatory breast cancer is classified as T4 and is stage IIIB unless it has spread to distant lymph nodes or organs, in which case it would be stage IV.

Stage IIIC: any T, 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 (N3).

• Cancer has spread to the lymph nodes under the clavicle (collar bone) (N3).

• Cancer has spread to the lymph nodes above the clavicle (N3).

• Cancer involves axillary lymph nodes and has enlarged the internal mammary lymph nodes (N3).

• Cancer has spread to 4 or more axillary lymph nodes, and tiny amounts of cancer are found in internal mammary lymph nodes on sentinel lymph node biopsy (N3).

The cancer hasn't spread to distant sites (M0).

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

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, and are based on women who were diagnosed with breast cancer between 1988 and 2001. 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) take into account the fact that some patients with cancer will die from other causes. They are considered to be a more accurate way to describe the outlook for patients with a particular type and stage of cancer.

• The SEER database does not divide survival rates by substages, such as IIA and IIB. The rates for these substages are likely to be close to the rate for the overall stage. For example, the survival rate for stage IIA is likely to be slightly higher than that listed for stage II, while the survival rate for stage IIB would be expected to be slightly lower. Also, staging for breast cancer changed in 2010. The survival data listed here is based on the older staging system.

• These numbers were taken from patients treated several years ago. Although they are among the most current numbers we have available, improvements in treatment since then mean that the survival rates for people now being diagnosed with these cancers may be higher.

• While survival statistics can sometimes be useful as a general guide, 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 can tell you how these numbers may apply to you, as he or she is familiar with the aspects of your particular situation.

Last Medical Review: 09/18/2009
Last Revised: 09/18/2009