ON THIS PAGE: You will learn about how doctors describe a cancer’s growth or spread. This is called the stage. To see other pages in this guide, use the colored boxes on the right side of your screen, or click “Next” at the bottom.
Staging is a way of describing where the cancer is located, if or where it has spread, and whether it is affecting other parts of 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 and histologic grade (measure of how much a tumor looks like healthy tissue when viewed under a microscope) helps the doctor to decide what kind of treatment to recommend 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. 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)
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.
Here are more details on each part of the TNM system for NPC.
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: This 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.
T1: The tumor has not spread beyond the nasopharynx.
T2: The tumor extends into the soft tissue of the middle throat.
T3: The tumor extends into bony structure or into the area behind the nose.
T4: The tumor extends inside the head to an area of the brain or into the lower part of the throat.
Node. The “N” in the TNM staging system is for lymph nodes, the tiny, bean-shaped organs that help fight infection. Lymph nodes near where the cancer started are called regional lymph nodes. Lymph nodes in other parts of the body are called distant lymph nodes.
In people with NPC, doctors examine lymph nodes in a triangle-shaped area formed by three points: where the neck meets the shoulder, where the collarbone joins the tip of the shoulder, and where the front half of the collarbone meets the base of the neck.
NX: The regional lymph nodes cannot be evaluated.
N0: There is no evidence of cancer in the regional lymph nodes.
N1: Cancer has spread to lymph nodes above the triangular area described above. The lymph nodes are on the same side of the neck as the primary tumor, and the cancer found in the lymph nodes is 6 centimeters (cm) or smaller.
N2: Cancer has spread to lymph nodes on both sides of the neck, above the triangular area, but the cancer is 6 cm or smaller.
N3: Cancer found in lymph nodes is larger than 6 cm or is found in lymph nodes located in the triangle.
N3a: Cancer found in the lymph nodes is larger than 6 cm.
N3b: Cancer has extended to the triangle region.
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: Cancer has not spread to other parts of the body.
M1: Cancer 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: A carcinoma in situ (Tis) with no spread to lymph nodes (N0) or distant metastasis (M0).
Stage IIA: A tumor that has extended beyond the nasopharynx (T2) but has not spread to lymph nodes (N0) or to distant parts of the body (M0).
Stage III: This describes a noninvasive and invasive tumor (T1 or T2) that have spread to lymph nodes (N1 or N2) but have not metastasized (M0), or it describes a larger tumor (T3) with or without nodal involvement (N0, N1, or N2) and no metastasis (M0).
Stage IVA: This describes any invasive tumor (T4) 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 cancer (any T) with more significant nodal involvement (N2) but no metastasis (M0).
Recurrent: Recurrent cancer is cancer that has come back after treatment. If there is a recurrence, the cancer may need to be staged again (called re-staging) using the system above.
Histologic grade (G). Doctors also describe a primary tumor by its grade, which is determined by using a microscope to examine tissue from a tumor (called a histologic examination). The doctor compares the tumor tissue with healthy tissue and assigns a histologic grade based on how similar they look. Healthy tissue contains many different types of cells grouped together, which is described as being differentiated. Tissue from a tumor usually has cells that look more alike, which is described as being poorly differentiated. Generally, the lower the grade, the better the prognosis. A tumor's grade is described using the letter "G" and a number.
GX: The grade cannot be evaluated.
G1: The tumor sample looks more like healthy tissue (well differentiated).
G2: The cells in the tumor are only moderately differentiated.
G3: The cells in the tumor don’t resemble those found in healthy tissue (poorly differentiated).
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 .
Information about the cancer’s stage and grade will help the doctor recommend a treatment plan. Choose “Next” (below, right) to continue reading about treatment options for NPC. Or, use the colored boxes located on the right side of your screen to visit any section.