Staging is the process of finding out how much cancer there is in the body and where it is located. Doctors use this information to plan treatment and to help find out a person’s outlook (prognosis). Cancers with the same stage usually have similar outlooks and are often treated the same way. The cancer stage is also a way for doctors to describe the extent of the cancer when they communicate with each other about a person’s case.

Doctors need to know the amount and location of cancer in the body to make sure a person gets the proper treatment for his or her specific cancer. For example, the treatment for early stage breast cancer may be surgery and radiation, while a more advanced stage of breast cancer may require treatment with chemotherapy. Doctors also use the stage to help predict the course a cancer is likely to take.

For most cancers, the stage is based on 3 main factors:

• the original (primary) tumor's size and whether or not the tumor has grown into other nearby areas
• whether or not the cancer has spread to the nearby lymph nodes
• whether or not the cancer has spread to distant areas of the body

Some cancers of the blood, such as leukemias, are not staged in this way because they are assumed to be in all parts of the body. Cancers in or around the brain are not staged using the TNM system, since these cancers can interfere with vital functions of the brain and body before they even begin to spread.

Doctors gather different types of information about a cancer to determine its stage. Depending on where the cancer is located, the physical exam may give some clue as to the extent of the cancer. Imaging tests such as x-rays, CT scans, and MRI scans may also provide information about where a cancer may be located in the body. Removing tumors or pieces of tumors and looking at them under the microscope (biopsy) often confirms the diagnosis of cancer, but it can also help stage the cancer. Samples can be removed either during surgery or during less invasive biopsy procedures. (The different techniques used to remove and examine samples are described in our Surgery document.)

There are different types of staging.

Clinical staging is an estimate how much cancer there is based on the results of the physical exam, imaging tests (x-rays, CT scans, etc.) and sometimes biopsies of affected areas. For certain cancers the results of other tests, such as blood tests, are also used in staging.

Pathologic staging can only be done on patients who have had surgery to remove or explore the extent of the cancer. It combines the results of clinical staging (physical exam, imaging tests, etc.) with the results from the surgery. In some cases, the pathologic stage may be different from the clinical stage (for example, if the surgery shows the cancer has spread more than it was thought to have spread before surgery.)

Restaging is sometimes used to determine the extent of the disease if a cancer recurs (comes back) after treatment. This is done to help decide what the best treatment option would be at this time. This type of staging is not common, as discussed in the section "A Cancer's Stage Does Not Change."

At one time there were many different systems used to stage cancers, and sometimes different systems were used to stage the same type of cancer. Although some of the better ones are still used, many of these systems did not give doctors very useful information.

The American Joint Committee on Cancer (AJCC) developed the TNM classification system as a tool for doctors to stage different types of cancer based on certain standard criteria. It has replaced many of the older staging systems. In the TNM system, each cancer is assigned a T, N, and M category.

The T category describes the original (primary) tumor. The tumor size is usually measured in centimeters (2 and 1/2 centimeters is about 1 inch) or millimeters (10 millimeters = 1 centimeter.)

• TX means the tumor can't be measured or evaluated.
• T0 means there is no evidence of primary tumor (the primary tumor cannot be found).
• Tis means the cancer is in situ (the tumor has not started growing into the structures around it).
• The numbers T1–T4 describe the tumor size and/or level of invasion into nearby structures. The higher the T number, the larger the tumor and/or the further it has grown into nearby structures.

The N category describes whether or not the cancer has reached nearby lymph nodes.

• NX means the nearby lymph nodes can't be measured or evaluated.
• N0 means nearby lymph nodes do not contain cancer.
• The numbers N1–N3 describe the size, location, and/or the number of lymph nodes involved. The higher the N number, the more lymph nodes are involved.

The M category tells whether there are distant metastases (spread of cancer to other parts of body).

• MX means metastasis can't be measured or evaluated.
• M0 means that no distant metastases were found.
• M1 means that distant metastases were found (the cancer had spread to distant organs or tissues.)

Each cancer type has its own version of this classification system, so letters and numbers don't always mean the same thing for every kind of cancer. For example, for some cancers, classifications may have subcategories, such as T3a and T3b, while others may not have an N3 category.

Once the T, N, and M have been learned, they are combined, and an overall "stage" of I, II, III, or IV is assigned. (Sometimes these stages are subdivided as well, using letters such as IIIA and IIIB.)

For example, a T1, N0, M0 breast cancer would mean that the primary breast tumor is less than 2 cm across (T1), does not have lymph node involvement (N0), and has not spread to distant parts of the body (M0). This would make it a stage I cancer.

A T2, N1, M0 breast cancer would mean that the cancer is more than 2 cm but less than 5 cm across (T2), has reached only the lymph nodes in the underarm area (N1), and has not spread to distant parts of the body. This would make it a stage IIB cancer.

Stage I cancers are the least advanced and often have a better prognosis (outlook for survival). Higher stage cancers are often more advanced but in many cases can still be treated successfully.

Staging systems other than the TNM system are often used for Hodgkin disease and other lymphomas, and some childhood cancers. The International Federation of Gynecologists and Obstetricians (FIGO) has a staging system for cancers of the female reproductive organs. The TNM stages closely match the FIGO stages, which makes it fairly easy to convert stages between these 2 systems.

Other, older staging systems (such as the Dukes system for colorectal cancer) may still be used by some doctors. If your doctor uses another staging system, you may want to find out if the stage can be converted into the TNM system. This will often help if you want to read more about your cancer and its treatment, since TNM is more widely used.

An important point some people have trouble understanding is that the stage of a cancer does not change over time, even if the cancer progresses. A cancer that comes back or spreads is still referred to by the stage it was given when it was first diagnosed.

For example, if a woman was first diagnosed with "stage II breast cancer," but the cancer now has spread to the bones, the cancer is called "stage II breast cancer with recurrent disease in the bones" (if the cancer went away with treatment) or "stage II breast cancer with metastasis in the bones" (if the cancer never went away completely). This is not "stage IV breast cancer." A stage IV breast cancer refers to a cancer that has already spread to a distant part of the body when it is first diagnosed. A person keeps the same diagnosis stage, but more information is added to the diagnosis to explain the current disease status.

This is important to understand because survival statistics and information on treatment by stage for specific cancer types refer to the stage when the cancer was first diagnosed. The survival statistics related to stage II breast cancer that has recurred in the bones may not be the same as the survival statistics for stage IV breast cancer.

When certain cancers come back, a doctor might restage the cancer if more treatment is being planned. This often means going through the same process that was done when the cancer was first diagnosed: exams, imaging tests, biopsies, and possibly surgery to restage the cancer. If the cancer is restaged, the stage will be recorded with a lower-case "r" before the restaged designation. A restaging process that finds T2, N3, M1, for instance, would be written rT2, rN3, rM1. The stage grouping IV would be written stage rIV rather than stage IV, to distinguish it from the stage assigned at diagnosis. The original stage at diagnosis still stays the same. Restaging is not often done in cancer treatment, although it is more common in clinical trials.

Your prognosis is affected by the type of cancer you have, but it is also strongly influenced by the cancer's stage. For some cancers, another important factor that is considered along with clinical stage is tumor grade. The grade is assigned after a biopsy of the cancerous tissue has been examined. Tumor grade describes how different the cancer cells look compared to normal ones.

Grade

Tumor grade is considered when making treatment decisions and is another factor that affects prognosis for some kinds of cancer. The grade of the cancer reflects how abnormal the cancer cells look under the microscope. Grading is done by a pathologist who compares the cancer cells from the biopsy to normal cells. (A pathologist is a doctor who is specially trained in diagnosis and classification of diseases by lab tests, such as looking cells under a microscope.) Grade is important because cancers with more abnormal-looking cells tend to grow and spread more quickly. Higher grade cancers (meaning that the cancer cells look very abnormal) usually have a worse prognosis, and sometimes need different treatments.

The American Joint Committee on Cancer (AJCC) recommends the following cancer grading classifications:

• GX: Grade cannot be determined 
• G1: Well-differentiated (the cancer cells look a lot like normal cells) 
• G2: Moderately well-differentiated (cancer cells look somewhat like normal cells) 
• G3: Poorly differentiated (cancer cells don't look much like normal cells) 
• G4: Undifferentiated (the cancer cells don’t look anything like normal cells)

The lower the cancer grade the better the prognosis. G1 cancers are linked to the best outcomes. G4 is associated with the worst outcomes and the others fall in between.

There are problems with grading, though. For example, several different grade levels may be found in one tumor or the tumor grade may change with time.

There are also several grading systems for different types of cancer, such as the Gleason grades for prostate cancer or the Kernohan grades for brain tumors. Each grading system divides cancer cells into those with the most abnormal cells, the least abnormal cells, and those in between. Generally, whatever grading system is used, the lower numbers indicate less aggressive cancers while the higher numbers suggest more rapid cancer cell growth and spread.

In addition to stage and grade, your outlook is also influenced by the treatment you receive, your general health, and many other factors that your doctor will take into account.

If you are looking for details on staging or grading for a particular type of cancer, this information is contained in each of our documents on specific cancer types. You can get copies of any of these cancer site documents by calling our toll free number.

Additional Resources

More Information From Your American Cancer Society

We have selected some related information that may also be helpful to you. These materials may be ordered from our toll-free number, 1-800-ACS-2345.

A Message of Hope: Coping with Cancer in Everyday Life (also available in Spanish)

After Diagnosis: A Guide for Patients and Families (also available in Spanish)

Talking with Your Doctor (also available in Spanish)

Understanding Chemotherapy (also available in Spanish)

Understanding Radiation Therapy (also available in Spanish)

National Organizations and Web Sites*

In addition to the American Cancer Society, other sources of patient information and support include the following:

National Cancer Institute
Telephone: 1-800-4-CANCER (1-800-422-6237)
Internet Address: www.cancer.gov

*Inclusion on this list does not imply endorsement by the American Cancer Society.

Please call 1-800-ACS-2345 any time any day you have questions or need help. The American Cancer Society has information, resources, and support available on any cancer-related topic.

References

Greene FL, Page DL, Fleming ID, Fritz AG, Balch CM, Haller DG, Morrow M, eds. American Joint Committee on Cancer Staging Manual. 6th ed. New York, NY: Springer; 2002.

Yarbro CH, Frogge MH, Goodman M, Groenwald SL, eds. Cancer Nursing Principles and Practice. 5th ed. Sudbury, MA: Jones and Bartlett Publishers, Inc. 2000.

Updated: 4/05/07