Staging

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.

There are a number of methods that are used to determine the stage of sarcoma. These systems differ somewhat, but all rely on overall stage to predict prognosis.

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 the rest 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)
  Note: Most sarcomas (except epithelioid sarcoma, some subtypes of rhabdomyosarcoma, and clear cell sarcoma) rarely spread to lymph nodes, so surgeons do not routinely test lymph nodes for most types of sarcoma.
  
  
• Has the cancer metastasized to other parts of the body? (Metastasis, M)

When staging sarcoma, two other factors are added to the TNM system: depth (D) and grade (G). This is different than staging for many other types of cancer.

Tumor. Using the TNM system, the "T" plus a number (0 to 2) and letter (a or b) 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 more detail. Specific tumor stage information is listed below.

Depth (D) helps describe the tumor (T). It is described as either superficial (the tumor is above the body's superficial tissue) or deep (the tumor is either beneath the body's superficial tissue or invades the deep tissue).

TX: The primary tumor cannot be evaluated.

T0: There is no evidence of a primary tumor.

T1:The size of the tumor is 5 centimeters (cm) or smaller.

T1a: The tumor is superficial.

T1b: The tumor is deep.

T2: The size of the tumor is larger than 5 cm.

T2a: The tumor is superficial.

T2b: The tumor is deep.

Node. The "N" in the TNM staging system stands for lymph nodes, the tiny, bean-shaped organs located all over the body that normally help fight infections and cancer as part of the body's immune system. Each type of tumor drains into lymph nodes nearby called regional lymph nodes. As noted above, lymph node involvement is unusual for soft tissue sarcoma.

NX: The regional lymph nodes cannot be evaluated.

N0: The cancer has not spread to the regional lymph nodes.

N1: The cancer has spread to the regional lymph nodes.

Metastasis. The "M" in the TNM system indicates whether the cancer has spread to other parts of the body.

MX: Metastasis cannot be evaluated.

M0: The cancer has not metastasized.

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

Histologic grade (G). Histologic grade describes how different the cancer cells are from normal tissue cells when examined under a microscope. A tumor's grade is described using the letter “G” and a number. The following is a commonly used grading system, but there are others that may alternatively be used. For instance, some doctors grade sarcomas as either “low grade” or “high grade”.

GX: The tumor grade cannot be identified.

G1: Describes cells that look more like normal tissue cells (well differentiated).

G2: The cells are somewhat different (moderately differentiated).

G3: The cells look very different from normal cells (poorly differentiated).

G4: The cells barely resemble normal cells (undifferentiated).

Cancer stage grouping

Doctors assign the stage of the cancer by combining the T, N, and M classifications. For sarcoma, stages I and II are described in smaller groups according to the tumor's depth (D).

Stage I: The tumor is low grade (G1), small, and either superficial or deep (T1a, T1b, T2a, T2b). It has not spread to lymph nodes or to other parts of the body (N0, M0).

Stage II: The tumor is high grade (G2, G3, or G4), small or superficial (T1a or T2a). It has not spread to lymph nodes or to other parts of the body (N0, M0).

Stage III: The tumor is high grade (G3 or G4), large, and deep (T2b). It has not spread to lymph nodes or to other parts of the body (N0, M0).

Stage IV: The tumor has spread to lymph nodes (N1) or other parts of the body (M1). The tumor can be any size (T1 or T2) and any grade (G1, G2, G3, or G4).

This staging system applies to all types of soft tissue sarcoma except Kaposi's sarcoma, dermatofibrosarcoma, and desmoid type of fibrosarcoma grade 1. Also excluded from this staging system is sarcoma that begins in the dura mater (the membrane lining the brain), including the brain, and in solid organs and hollow viscera, such as the bowel or bladder.

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.cancerstaging.net.