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Staging is a way of describing where the cancer is located, if or where it has spread, and whether 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 judges three factors: 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.
TX: The primary tumor cannot be evaluated.
T0: No evidence of a tumor is found.
Tis: A stage called carcinoma (cancer) in situ. This is a very early cancer where cancer cells are found only in one layer of tissue.
Tumors of the paranasal sinuses are also evaluated by their exact location. (See Overview.)
Primary tumor (T) in the maxillary sinus
T1: The tumor is limited to the inside of the sinus and does not erode or invade bone.
T2: The tumor erodes or invades bone surrounding the sinuses.
T3: The tumor invades the surrounding bone, the skin of the cheek, or the other sinuses.
T4a: The tumor invades the bone surrounding the eye, the skin of the cheek, or the bones in the back of the throat.
T4b: The tumor invades any of the following: the back of the eye, the brain area, or the bones of the skull, other than those behind the nose or the back of the head.
Primary tumor (T) in the nasal cavity and ethmoid sinus
T1: The tumor is limited to the inside of the sinus with no involvement with the bone.
T2: The tumor extends into the nasal cavity.
T3: The tumor extends into the maxillary sinus or to the bone surrounding the eye.
T4a: The tumor has spread throughout the facial bones or into the base of the skull.
T4b: The tumor invades any of the following: the back of the eye, the brain area, or the back of the head.
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: The regional lymph nodes cannot be evaluated.
N0: There is no evidence of cancer in the regional lymph nodes.
N1: The cancer has spread to a single lymph node on the same side as the primary tumor, and the cancer found is 3 centimeters (cm) or smaller.
N2: This describes any of these conditions:
N2a: The cancer has spread to a single lymph node on the same side as the primary tumor, and it is larger than 3 cm but not larger than 6 cm.
N2b: The cancer has spread to more than one lymph node on the same side as the primary tumor, but none measure larger than 6 cm.
N2c: The cancer has spread to more than one lymph node on either side of the body, but none measure larger than 6 cm.
N3: The cancer is found in at least one nearby lymph node and 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: Distant metastasis cannot be evaluated.
M0: The cancer has not spread to other parts of the body.
M1: The cancer has spread to another part(s) of the body.
Cancer stage grouping
Doctors assign the stage of the cancer by combining the T, N, and M classifications.
Stage 0: This is a very early cancer (Tis) with no spread to lymph nodes (N0) or distant metastasis (M0).
Stage I: This is a noninvasive cancer (T1) with no spread to lymph nodes (N0) and no distant metastasis (M0).
Stage II: This is an invasive cancer (T2) that has not spread to lymph nodes (N0) or to distant parts of the body (M0).
Stage III: This includes invasive cancer (T3) with no spread to regional lymph nodes (N0) or metastasis (M0), as well as invasive cancer (T1, T2, T3) that has spread to regional lymph nodes (N1) but shows no sign of metastasis (M0).
Stage IVA: This is an invasive cancer (T4a) that either has no lymph node involvement (N0) or has spread to only one same-sided lymph node (N1) but with no metastasis (M0). It is also used for any cancer (any T) with more significant nodal involvement (N2) but with no metastasis (M0).
Stage IVB: This is an invasive cancer (any T) that has spread to lymph nodes (any N) but has no metastasis (M0). It is also used for any cancer (any T) that is found in lymph nodes and is larger than 6 cm (N3) but has no metastasis (M0).
Stage IVC: This refers to any tumor (any T, any N) when there is evidence of distant spread (M1).
Tumor grade. Doctors also describe a primary tumor by its grade (G), 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 lower the grade), the better the prognosis.
GX: The grade cannot be evaluated.
G1: 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. If there is a recurrence, the cancer may need to be staged again (called re-staging) using the system above.
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, Seventh Edition (2010) published by Springer-Verlag New York, www.cancerstaging.net.