Staging is a way of describing 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 of the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient’s prognosis (chance of recovery). There are different stage descriptions for different types of cancer.
One tool that doctors use to describe the stage is the TNM system. 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 are five stages: stage 0 (zero) and stages I through IV (one through four). The stage provides a common way of describing the cancer, so doctors can work together to plan the best treatments.
TNM is an abbreviation for tumor (T), node (N), and metastasis (M). Doctors look at these three factors to determine the stage of cancer:
- How large is the primary tumor and where is it located? (Tumor, T)
- Has the tumor spread to the lymph nodes? (Node, N)
- Has the cancer metastasized to other parts of the body? (Metastasis, M)
Tumor. Using the TNM system, the "T" plus a letter or number (0 to 4) is used to describe the size and location of the tumor. Some stages are also divided into smaller groups that help describe the tumor in even more detail. Specific tumor stage information is listed below.
Larynx
TX: Indicates the primary tumor cannot be evaluated.
T0: No evidence of a tumor is found.
Tis: Describes a stage called carcinoma (cancer) in situ. This is a very early cancer where cancer cells are found only in one layer of tissue.
When describing a later stage tumor, doctors divide the larynx into three regions: the glottis, the supraglottis, and the subglottis.
Glottis tumor of the lung
T1: Describes a tumor that is limited to the vocal folds, but it does not affect movement of the folds.
T1a: Describes a tumor in just the right or left vocal fold.
T1b: Describes a tumor in both vocal folds.
T2: Describes a tumor that has spread to the supraglottis and/or the subglottis. T2 also describes a tumor that affects the movement of the vocal fold, without paralyzing the fold.
T3: Describes a tumor that is limited to the larynx and paralyzes at least one of the vocal folds.
T4a: The tumor has spread to the thyroid cartilage and/or the tissue beyond the larynx.
T4b: The tumor has spread to the chest area and encases the arteries.
Supraglottis tumor of the larynx
T1: Describes a tumor located in a single area above the vocal folds that doesn’t affect movement of the vocal folds.
T2: Describes a tumor that started in the supraglottis, but has spread to the mucus membranes that line other areas, such as the base of the tongue.
T3: Describes a tumor that is limited to the larynx with vocal fold involvement and/or has spread to surrounding tissue.
T4a: The tumor has spread through the thyroid cartilage and/or the tissue beyond the larynx.
T4b: The tumor has spread to the chest area and encases the arteries.
Subglottis tumor of the larynx
T1: Describes a tumor that is limited to the subglottis.
T2: Describes a tumor that has spread to the vocal folds and may or may not affect movement of the folds.
T3: Describes a tumor that is limited to the larynx and affects the vocal folds.
T4a: The tumor has spread to the cricoid or thyroid cartilage and/or the tissue beyond the larynx.
T4b: The tumor has spread to the chest area and encases the arteries.
Hypopharynx
T1: Describes a small tumor, not larger than 2 centimeters (cm), that is limited to a single site in the lower throat.
T2: Describes a tumor that involves more than one site in the lower throat, but does not touch the voice box; or, a tumor that measures larger than 2 cm, but not larger than 4 cm.
T3: Describes a tumor that is larger than 4 cm or a tumor that has spread to the larynx.
T4a: Describes a tumor that has spread into nearby structures, such as the thyroid, the arteries that carry blood to the brain, or the esophagus.
T4b: The tumor has spread to the prevertebral fascia (space in front of the spinal cord), encases the arteries, or involves mediastinal (chest-area) structures.
Node. The “N” in the TNM staging system stands for lymph nodes, the tiny, bean-shaped organs that help fight infection. Lymph nodes near the head and neck are called regional lymph nodes. Lymph nodes in other parts of the body are called distant lymph nodes. Since there are many nodes in the head and neck area, careful assessment of lymph nodes is an important part of staging.
NX: Indicates that the regional lymph nodes cannot be evaluated.
N0: There is no evidence of cancer in the regional nodes.
N1: Indicates that cancer has spread to a single node on the same side as the primary tumor and the cancer found in the node is 3 cm or smaller.
N2: Describes any of the following conditions:
N2a: Cancer has spread to a single lymph node on the same side as the primary tumor, and is larger than 3 cm, but not larger than 6 cm.
N2b: Cancer has spread to more than one lymph node on the same side as the primary tumor, and none measure larger than 6 cm.
N2c: Cancer has spread to more than one lymph node on either side of the body, and none measure larger than 6 cm.
N3: Indicates that the cancer found in the lymph nodes is larger than 6 cm.
Distant metastasis. The "M" in the TNM system indicates whether the cancer has spread to other parts of the body.
MX: Indicates that distant metastasis cannot be evaluated.
M0: Indicates that the cancer has not spread to other parts of the body.
M1: Describes cancer that has spread to other parts of the body.
Cancer stage grouping
Doctors assign the stage of the cancer by combining the T, N, and M classifications.
Stage 0: Describes a carcinoma in situ (Tis), with no spread to lymph nodes (N0) or distant metastasis (M0).
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Stage I: Describes a small tumor (T1), with no spread to lymph nodes (N0) and no distant metastasis (M0).
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Stage II: Describes a tumor with some spread to nearby areas (T2), but has not spread to lymph nodes (N0) or to distant parts of the body (M0).
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Stage III: Describes any larger tumor (T3), with no spread to regional lymph nodes (N0) or metastasis (M0), or a smaller tumor (T1, T2) that has spread to regional lymph nodes (N1) but has no sign of distant metastasis (M0).
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Stage IVA: Describes any invasive tumor (T4a), with either no lymph node involvement (N0) or spread to only a single same-sided lymph node (N1), but no metastasis (M0). It is also used for any tumor (any T) with more significant spread to the lymph nodes (N2), but no metastasis (M0).
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Stage IVB: Describes any cancer (any T) with extensive spread to lymph nodes (T3), but no metastasis (M0).
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Stage IVC: Indicates there is evidence of distant spread (any T, any N, M1).
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Tumor grade. Doctors also describe a primary tumor by its grade, which is determined by using a microscope to examine tissue from a tumor. The doctor compares the tumor tissue with normal tissue. Normal tissue contains many different types of cells grouped together, which is called differentiated. Tissue from tumors usually has cells that look more alike, called poorly differentiated. Generally, the more differentiated the tissue, the better the prognosis.
GX: Indicates the grade cannot be evaluated.
G1: Indicates the cells look more like normal tissue (well differentiated).
G2: The cells are only moderately differentiated.
G3: The cells don’t resemble normal tissue (poorly differentiated).
Recurrent: Recurrent cancer is cancer that comes back after treatment.
Used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original source for this material is the AJCC Cancer Staging Manual, Sixth Edition (2002) published by Springer-Verlag New York, www.springer-ny.com.
Last Updated: November 04, 2008
