Summary
Staging is performing exams and tests to learn the extent of the cancer within the body, especially whether the disease has spread from the original site to other parts of the body. It is important to know the stage of the disease in order to plan the best treatment.
Staging systems for cancer have evolved over time. They continue to change as scientists learn more about cancer. Some staging systems cover many types of cancer; others focus on a particular type.
The TNM system is one of the most commonly used staging systems.
The doctor most familiar with your situation is in the best position to provide staging information and to answer staging questions.
TNM Staging
The TNM system is one of the most commonly used staging systems.
The TNM system is based on the following:
- The extent of the tumor (T)
- The extent of spread to the lymph nodes(N)
- The presence of metastasis (M).
A number is added to each letter to indicate the size or extent of the tumor and the extent of spread.
The National Cancer Institute provides the following examples of TNM Staging:
Primary Tumor (T) | |
TX | Primary tumor cannot be evaluated |
T0 | No evidence of primary tumor |
Tis | Carcinoma in situ (early cancer that has not spread to neighboring tissue) |
T1, T2, T3, T4 | Size and/or extent of the primary tumor |
Regional Lymph Nodes (N) | |
NX | Regional lymph nodes cannot be evaluated |
N0 | No regional lymph node involvement (no cancer found in the lymph nodes) |
N1, N2, N3 | Involvement of regional lymph nodes (number and/or extent of spread) |
Distant Metastasis (M) | |
MX | Distant metastasis cannot be evaluated |
M0 | No distant metastasis (cancer has not spread to other parts of the body) |
M1 | Distant metastasis (cancer has spread to distant parts of the body) |
For example:
- Breast cancer T3 N2 M0 refers to a large tumor that has spread outside the breast to nearby lymph nodes, but not to other parts of the body.
- Prostate cancer T2 N0 M0 means that the tumor is located only in the prostate and has not spread to the lymph nodes or any other part of the body.
For many cancers, TNM combinations correspond to one of five stages. Criteria for stages differ for different types of cancer. For example, bladder cancer T3 N0 M0 is stage III; however, colon cancer T3 N0 M0 is stage II.
Stage | Definition |
Stage 0 | Carcinoma in situ (early cancer that is present only in the layer of cells in which it began). |
Stage I, Stage II, and Stage III | Higher numbers indicate more extensive disease: greater tumor size, and/or spread of the cancer to nearby lymph nodes and/or organs adjacent to the primary tumor. |
Stage IV | The cancer has spread to another organ. |
Tests Used To Determine Staging
The types of tests used for staging depend on the type of cancer. Tests include the following:
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Common Elements Of Most Staging Systems
The common elements considered in most staging systems are:
- Location of the primary tumor (the original tumor.)
- Tumor size and number of tumors,
- Lymph node involvement (spread of cancer into lymph nodes),
- Cell type and tumor grade* (how closely the cancer cells resemble normal tissue), and
- Presence or absence of metastasis (spread of the cancer from the original location).