Staging is a way of describing a cancer, such as where it is located, if or where it has spread, and if it is affecting the functions of other organs in the body. Doctors use diagnostic tests to determine the cancer’s stage, so staging may not be complete until all the tests are finished. Knowing the stage helps the doctor:

• Plan treatment
  
  
• Predict prognosis (chance of recovery)
  
  
• Interpret treatment effectiveness
  
  
• Communicate about the diagnosis in a clear, common language with the cancer treatment team
  
  
• Analyze larger populations with the same diagnosis as part of cancer research to evaluate new, more effective treatments

The staging system used by doctors is the TNM system of the American Joint Committee on Cancer (AJCC). TNM is an abbreviation for tumor (T), node (N), and metastasis (M), or cancer that has spread to other areas of the body. This system uses three criteria to judge the stage of the cancer: the tumor itself, the lymph nodes around the tumor, and if the tumor has spread to other parts of the body. The results are combined to determine the stage of cancer for each person. There is a separate TNM system for each type of cancer. Below are general descriptions of the TNM staging system. Refer to the Cancer.Net Guides to Cancer for more detailed staging descriptions that apply to each tumor type.

T: The letter "T" (local tumor growth) describes the extent of the cancer in its original location. Each cancer is described using a term T0, T1, T2, T3, or T4. The larger or more extensive the tumor, the larger the number assigned. The T number reflects a combination of the size and the extent to which the tumor invades nearby structures.

N: The letter "N" (regional lymph node) describes whether the is cancer present in the lymph nodes near the tumor, and, in some types of cancer, how many of these lymph nodes contain cancer cells. The lymph nodes are tiny, bean-shaped organs that are located throughout the body that help fight infections as part of the immune system. Each cancer may be assigned one of these terms: N0 (meaning no cancer is found in the nodes), N1, N2, or N3. In many instances, the more lymph nodes with cancer, the larger the number assigned. For other tumors, the location of the nodes that have cancer may determine the N rating.

M: The letter "M" (distant metastasis) describes if the cancer has metastasized from its original (primary) location to other distant areas of the body. Each cancer is assigned either M0 (no metastasis), or M1 (metastasis has occurred).

For some cancers, the TNM categories are broken down into smaller subsets and described using lowercase letters or subscripts. It is important to discuss with your doctor what these subcategories mean with regard to your diagnosis.

For some types of cancer, other information about the cancer is also used in defining the stage. This includes the results of blood tests and specific tests that are done on the cancer tissue itself.

Cancer stage grouping

Doctors assign the stage of cancer by combining the T, N, and M classifications. Most cancers have four stages, which are given the Roman numerals, I, II, III, or IV. Some cancers have a stage 0 (zero), which is used to describe cancer in situ, meaning that cancer has not become invasive and does not have the capacity to spread. These cancers are highly curable. Stage I generally indicates a cancer that is small, has not invaded deeply into the surrounding tissues, and has not spread either to lymph nodes or other parts of the body. This is often called early-stage cancer. Stage II and III cancers have increasing degrees of size, invasion, and spread to lymph nodes, but have not spread in amounts that can be detected to other parts of the body. Stage IV means that the cancer has spread to other organs or parts of the body, and may be referred to as advanced cancer.

In addition to the T, N, and M characteristics, there is other information about a cancer that may help your doctor determine the prognosis and define the best available treatment. In some cancers, this information is used in addition to T, N, and M to determine the stage group, and other information is used in addition to stage.

These other forms of information include:

Cancer grade. A cancer's grade describes how the cancer cells look under a microscope when compared with normal cells. The grade of a cancer can help the doctor predict how quickly the cancer will spread. In cancer that resembles healthy tissue, doctors can clearly see different types of cells grouped together (called well differentiated). In a higher-grade cancer, the cancer cells usually look less like healthy cells, or “wilder” (called poorly differentiated or undifferentiated). In general, tumors with more differentiated cells have a better prognosis. There are different methods used to assign a cancer grade for different types of cancers. For example, in prostate cancer a grading system called the Gleason Score is assigned that is very important to help determine the best treatment.

Tumor markers. Some types of cancer have characteristics that can be measured that give even more information than stage about the chance the cancer will spread, or whether specific treatments will be helpful. These are called tumor markers. One example of a tumor marker is the estrogen receptor in breast cancer. Read more about tumor markers for breast cancer. There are an increasing number of tumor markers available to help doctors determine the best treatment in many types of cancer.

Gene profiling systems. There are many genes in cancers that may help determine whether the cancer will spread or what treatment will be effective. Recent scientific advances have identified ways of providing a profile, or individual signature of a cancer, that helps doctors. These signature profiles are not available for many cancer types yet. However, many doctors think these profiles will become available in the next five to ten years for many or most cancer types. These profiles will allow treatment to be personalized to an individual’s cancer.

Other Staging Systems

The TNM system is used to describe most cancers that form solid tumors like breast, colon, and lung cancers. In addition to TNM staging, there are other staging systems used to classify additional types of cancer. Examples of these other systems include:

Central nervous system tumors (brain cancers). Because malignant (cancerous) brain tumors do not normally spread outside of the central nervous system (CNS, brain and spinal cord), only the "T" description of the TNM system applies. Currently, there is no universal staging system for central nervous system tumors.

Childhood cancers. AJCC does not include childhood cancers in its staging manual. Most childhood cancers are staged separately, according to other staging systems.

Leukemias and Lymphomas. Cancers of the blood are not described by the TNM system, since they do not form solid tumors. A leukemia is described according to subtypes and by how the cancer cells differ between types of leukemias. A lymphoma is described according to four stages that are based on the number and location of lymph nodes that contain cancer cells, whether the lymph nodes that contain cancer cells are on one or both sides of the diaphragm, and whether the cancer has spread to the bone marrow, spleen, or organs outside the lymphatic system, such as the liver, lungs, or brain.

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Last Updated: March 02, 2009