Stages of Cancer
Staging helps describe where a cancer is located, if or where it has spread, and whether it is affecting the other parts of the body. Doctors often use tests to determine a cancer’s stage. Staging may not be complete until all of the tests are finished. Knowing the stage helps the doctor:
- Plan treatment, including the type of surgery and whether chemotherapy or radiation therapy are needed
- Predict the chance that the cancer will come back after the original treatment
- Predict the chance of recovery
- Talk about the diagnosis in a clear, common language with the entire health care team
- Determine treatment effectiveness, and
- Compare larger populations with the same diagnosis to research new, more effective cancer treatments.
Doctors commonly use the American Joint Committee on Cancer’s (AJCC’s) TNM system to describe a cancer’s stage. Doctors use the results from tests and scans to answer these questions:
- How large is the primary tumor? Where is it located? (Tumor, T)
- Has the tumor spread to the lymph nodes? If so, where and how many? (Node, N)
- Has the cancer spread to other parts of the body? If so, where and how much? (Metastasis, M)
Listed below are the general descriptions of the TNM staging system. However, each type of cancer has a separate TNM system. Learn more specific staging information for each type of cancer.
- Tumor (T). The letter “T” plus a number (0 to 4) describes the size and location of the tumor, including how much the tumor has grown into nearby tissues. A larger tumor or one that has grown more deeply into the surrounding tissue receives a higher number. For some types of cancer, lowercase letters, such as “a,” “b,” or “m” (for multiple), are added to the “T” stage category to provide more detail.
- Node (N). The letter “N” plus a number (0 to 3) describes whether cancer has been found in the lymph nodes. It may also describe how many of the lymph nodes contain cancer. Lymph nodes are tiny, bean-shaped organs that help fight infection. Regional lymph nodes are located closest to where the cancer began. Distant lymph nodes are located in other parts of the body. Most often, the more lymph nodes with cancer, the larger the number assigned. However, for some tumors, the location of the lymph nodes with cancer may determine the “N” stage category.
- Metastasis (M). The letter “M” indicates whether the cancer has metastasized, or spread, to other parts of the body. If the cancer has not spread, it is labeled M0. If the cancer has spread, it is considered M1.
Cancer stage grouping
Doctors combine the T,N,M results to determine the stage of cancer for each person. Most cancers have four stages: stages I (one) to IV (four). Some cancers also have a stage 0 (zero).
- Stage 0. This stage describes cancer in situ, which means “in place.” Stage 0 cancers are still located in the place they started and have not spread to nearby tissues. This stage of cancer is often highly curable, usually by removing the entire tumor with surgery.
- Stage I. This stage is usually a small cancer or tumor that has not grown deeply into nearby tissues. It also has not spread to the lymph nodes or other parts of the body. It is often called early-stage cancer.
- Stage II and III. These stages indicate larger cancers or tumors that have grown more deeply into nearby tissue. They may have also spread to lymph nodes but not to other parts of the body.
- Stage IV. This stage means that the cancer has spread to other organs or parts of the body. It may also be called advanced or metastatic cancer.
In addition to the TNM staging system, your doctor may use other information to help determine the chance of recovery and decide on the best available treatment. This may include:
- Grade. The grade describes how much cancer cells look like healthy cells under a microscope. It also helps predict how quickly the cancer will spread. A tumor with cells that look more like healthy cells is called well-differentiated or low-grade. A tumor with cells that look less like healthy cells is described as poorly differentiated, undifferentiated, or high-grade. Different types of cancer have different methods to assign a cancer grade.
- Tumor markers. Tumor markers are substances found at higher than normal levels in the blood, urine, or body tissues of some people with cancer. Doctors and researchers have been discovering tumor markers for many types of cancer that can help determine the best treatment. For some cancers, certain tumor markers may be more helpful than stage in predicting how well a specific treatment will work or the chance that the cancer will spread. Learn more about testing for tumor markers.
- Tumor genetics. Many genes in cancer cells may help predict if the cancer will spread or what treatment(s) will work. Recent research studies have found ways to determine the genes involved in many types of cancer. In the future, this information may also help doctors target treatment to each person’s cancer.
Other Staging Systems
The TNM system is mainly used to describe cancers that form solid tumors, such as breast, colon, and lung cancers. However, doctors use other staging systems to classify other types of cancer, such as:
- Central nervous system tumors (brain tumors). Because cancerous brain tumors do not normally spread outside the brain and spinal cord, only the “T” description of the TNM system applies. Currently, no single staging system exists for central nervous system tumors.
- Childhood cancers. The AJCC does not include childhood cancers in its staging system. Doctors stage most childhood cancers separately according to other staging systems that are often specific to the cancer type.
- Cancers of the blood. The TNM system does not describe leukemia, lymphoma, or multiple myeloma since they usually do not form solid tumors. Each blood cancer has a unique staging system.
The stage of a cancer does not change over time. If the cancer comes back or spreads to another part of the body, it has the same stage as the first diagnosis. The more recent information about the size and spread of the cancer is added to the stage.
Sometimes, a doctor might restage a cancer to determine how well a treatment is working or to get more information about a cancer that has come back after treatment. This process uses the same staging system described above. Usually some of the same tests that were done when the cancer was first diagnosed will be repeated. After this, the doctor may assign the cancer a new stage. The doctor then adds a lowercase “r” before the new stage to show that it is different from that of the first diagnosis. However, this is not common.