Staging With Illustrations

Staging is a way of describing a 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 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.

TX: The primary tumor cannot be evaluated.

T0: There is no cancer in the esophagus.

Tis: Refers to carcinoma (cancer) in situ. Carcinoma in situ is very early cancer, where cancer cells are found only in one small area and have not spread at all. Cancer cells are in only the top lining of the esophagus without any spread into the lining.

T1: There is a tumor in the lamina propria and submucosa (the two inside layers of the esophagus). Cancer cells have spread into the lining of the esophagus.

T2: The tumor is in the muscularis propria (the third layer of the esophagus). Cancer cells have spread into but not through the muscle wall of the esophagus.

T3: The tumor is in the adventitia (the outer layer of the esophagus). Cancer cells have spread through the entire muscle wall of the esophagus into surrounding tissue.

T4: The tumor has spread outside the esophagus into areas around it. Cancer cells have spread to structures surrounding the esophagus, including the aorta (large blood vessel coming from the heart), windpipe, and diaphragm.

Node. The “N” in the TNM staging system stands for lymph nodes, the tiny, bean-shaped organs that help fight infection. In esophageal cancer, lymph nodes near the esophagus and in the chest are called regional lymph nodes. Lymph nodes in other parts of the body are called distant lymph nodes.

NX: The lymph nodes cannot be evaluated.

N0: The cancer was not found in the lymph nodes.

N1: The cancer has spread to the lymph nodes within the chest, near the tumor.

Distant metastasis. The "M" in the TNM system indicates whether the cancer has spread to other parts of the body. In esophageal cancer, metastasis is described depending on what part of the esophagus the cancer started in: the lower thoracic esophagus (closest to the stomach), middle or midthoracic esophagus, or upper thoracic esophagus (closest to the neck).

MX: Metastasis cannot be evaluated.

M0: The disease has not metastasized.

M1: There is metastasis to another part of the body.

Tumors of the lower thoracic esophagus

M1a: The cancer has spread to the celiac nodes (the lymph nodes in the abdomen).

M1b: The cancer has spread to other parts of the body.

Tumors of the midthoracic esophagus

M1a: This term is not used.

M1b: The cancer has spread to distant lymph nodes or other parts of the body.

Tumors of the upper thoracic esophagus

M1a: The cancer has spread to the cervical nodes (the lymph nodes in the neck).

M1b: The cancer has spread to other parts of the body.

Grading

Tumor grade. Grade may also be used to describe the tumor, using the letter “G,” in addition to the TNM system. Grade is determined based on how similar the tumor cells are to normal cells when viewed under a microscope. Normal tissue usually has different types of cells grouped together (also called differentiated tissue). Tissue that is cancerous usually is made up of cells that look more like each other. In general, the more differentiated the tissue, the better the prognosis.

G1: The tissue looks more like normal cells (well differentiated).

G2: The cells are somewhat more abnormal (somewhat differentiated).

G3: The tumor cells look very much abnormal and barely resemble normal cells (poorly differentiated).

G4: The cancer cells look almost alike and do not look like normal cells (not differentiated).

Cancer stage grouping

Doctors assign the stage of the cancer by combining the T, N, and M classifications.

Stage I:This is the same as T1 cancer, in which the cancer is located in only the two inside layers of the esophagus. (T1, N0, M0)

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Stage IIA: Cancer is in either of the two outer layers of the esophagus. (T2 or T3, N0, M0)

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Stage IIB: Cancer is in the inner layers of the esophagus and has spread to some lymph nodes near the tumor. (T1 or T2, N1, M0)

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Stage III: Cancer is in the outside layer of the esophagus or in the tissues near the esophagus. Cancer is also in the lymph nodes, either near the tumor or somewhere else in the body. (T3 or T4, N1, M0)

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Stage IV: Cancer has spread to other parts of the body. (Any T, Any N, M1)

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Stage IVA: Cancer has spread to the lymph nodes in the abdomen or neck. (Any T, Any N, M1a)

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Stage IVB: Cancer has spread to other parts of the body besides the lymph nodes. (Any T, Any N, M1b)

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Recurrent: Recurrent cancer is cancer that comes back after treatment. It may come back in the esophagus or in another part of the body.

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.