ON THIS PAGE: You will learn about how doctors describe a tumor’s growth or spread, as well as the way the sarcoma cells look when viewed under a microscope. This is called the stage and grade. Use the menu to see other pages.
Staging is a way of describing where the tumor is located, if or where it has spread, and whether it is affecting other parts of the body. Doctors use diagnostic tests to find out a sarcoma'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 it can help predict a patient's prognosis, which is the chance of recovery. There are different stage descriptions for different types of cancer.
Sarcomas that begin in organs are not assigned stage groupings. However, they are evaluated using the TNM system described below.
TNM staging system
One tool that doctors use to describe sarcoma is the TNM system. Doctors use the results from diagnostic tests and scans to answer these questions:
Tumor (T): How large is the primary tumor? Where is it located?
Node (N): Has the tumor spread to the lymph nodes? If so, where and how many?
Metastasis (M): Has the cancer spread to other parts of the body? If so, where and how much?
Grade (G): How different are the cancer cells from surrounding healthy cells?
Using the TNM system, the "T" plus a number (1 to 4) and letter (a, b, or c) is used to describe the size and location of the tumor. Tumor size is often measured in centimeters (cm). A centimeter is roughly equal to the width of a standard pen or pencil.
Tumor stage may also be divided into smaller groups that help describe the tumor in even more detail. Specific tumor information is listed below.
TX: The primary tumor cannot be evaluated.
T1: The tumor is confined only to the organ where it started.
T2: The tumor has spread into the tissue outside of the organ.
T2a: The tumor has grown into the membrane that covers organs, called the serosa, or the lining of the organs in the abdomen, called the visceral peritoneum.
T2b: The tumor has grown beyond the serosa.
T3: The tumor has spread to another organ.
T4: The tumor is found in more than 1 place in a particular organ or specific part of the body, called multifocal involvement.
T4a: The tumor involves 2 places in a single organ.
T4b: The tumor involves 3 to 5 places in a single organ.
T4c: The tumor involves more than 5 places in a single organ.
The “N” in the TNM staging system stands for lymph nodes. These tiny, bean-shaped organs help fight infection. Each type of tumor drains into nearby lymph nodes, called regional lymph nodes. Sarcoma rarely spreads to the lymph nodes and often they are not removed at the time of surgery.
N0 (N plus zero): The cancer has not spread to the regional lymph nodes, or it is unknown if lymph nodes are involved.
N1: The cancer has spread to the regional lymph nodes.
The "M" in the TNM system describes whether the cancer has spread to other parts of the body, called distant metastasis.
M0 (M plus zero): The cancer has not metastasized.
M1: There is metastasis to another part or parts of the body.
As described above, doctors also describe this type of cancer by its grade (G). The grade describes how much cancer cells look like healthy cells when viewed under a microscope.
The doctor compares the cancerous tissue with healthy tissue. Healthy tissue usually contains many different types of cells grouped together. If the cancer looks similar to healthy tissue and has different cell groupings, it is called “differentiated” or a “low-grade tumor.” If the cancerous tissue looks very different from healthy tissue, it is called “poorly differentiated” or a “high-grade tumor.” The cancer’s grade may help the doctor predict how quickly the cancer will spread. In general, the lower the tumor’s grade, the better the prognosis.
There are 4 grades for sarcoma: GX (the grade cannot be evaluated), G1, G2, and G3. The grades are determined based on the factors below:
Differentiation: How different the cancer cells are from normal tissue cells.
Mitotic count: How many tumor cells are dividing.
Tumor necrosis: How much of the tumor has cells that are dying.
The lower the combined score for these 3 factors, the lower the grade. A lower grade means that the tumor is less aggressive and that a patient’s prognosis is better. This is the recommended grading system from the French Federation of Cancer Centers Sarcoma Group (French Fédération Nationale des Centres de Lutte Contre le Cancer or FNCLCC), but other systems may also be used. For instance, some doctors grade sarcomas as either “low grade” or “high grade,” particularly if the tumor has been treated before surgery.
Used with permission of the American College of Surgeons, Chicago, Illinois. The original and primary source for this information is the AJCC Cancer Staging Manual, Eighth Edition (2017), published by Springer International Publishing.
Information about the cancer’s stage will help the doctor recommend a specific treatment plan. The next section in this guide is Types of Treatment. Use the menu to choose a different section to read in this guide.