Sarcoma: Types & Stages

Sarcoma: Types & Stages

There are many types of soft tissue tumors, and not all of them are cancerous. When the term sarcoma is part of the name of a disease, it means the tumor is malignant (cancer). Some soft tissue tumors behave in way in between a cancer and a non­cancer. These are called intermediate.

There are about 50 different types of soft tissue sarcomas (not all are listed here), such as:

  • Adult fibrosarcoma
  • Alveolar soft­part sarcoma
  • Angiosarcoma (includes hemangiosarcoma and lympangiosarcoma)
  • Clear cell sarcoma
  • Desmoplastic small round cell tumor
  • Epithelioid sarcoma
  • Fibromyxoid sarcoma, low­grade
  • Gastrointestinal stromal tumor (GIST): this is a type of sarcoma that develops in the digestive tract. It is covered in a separate document, Gastrointestinal Stromal Tumor (GIST).
  • Kaposi sarcoma: this is a type of sarcoma that develops from the cells lining lymph or blood vessels. It is covered in a separate document, Kaposi Sarcoma
  • Liposarcoma (includes dedifferentiated, myxoid, and pleomorphic liposarcomas)
  • Leiomyosarcoma
  • Malignant mesenchymoma
  • Malignant peripheral nerve sheath tumors (includes neurofibrosarcomas, neurogenic sarcomas, and malignant schwannomas)
  • Myxofibrosarcoma, low­grade
  • Rhabdomyosarcoma: this is the most common type of soft tissue sarcoma seen in children and is discussed in the separate document Rhabdomyosarcoma.
  • Synovial sarcoma
  • Undifferentiated pleomorphic sarcoma (previously known as malignant fibrous histiocytoma or MFH)

Many of these types are discussed in more detail later in this section. There are many other types of tumors called soft tissue sarcomas, but these are all quite rare.

Intermediate soft­tissue tumors include:

  • Dermatofibrosarcoma protuberans
  • Fibromatosis (also known as desmoid tumor, musculoaponeurotic fibromatosis, and aggressive fibromatosis
  • Hemangioendothelioma
  • Infantile fibrosarcoma
  • Solitary fibrous tumor

Grade (G)

The grade is a sign of how likely it is the cancer will spread. Previously, the grade of a sarcoma was only based on how normal the cells looked under the microscope (called differentiation). This was not very helpful, and under a new system (known as the French or FNCLCC system), grade is based on 3 factors:

  • Differentiation: Cancer cells are given a score of 1 to 3, with 1 being assigned when they look similar to normal cells and 3 being used when the cancer cells look very abnormal. Certain types of sarcoma are given a higher score automatically.
  • Mitotic count: How many cancer cells are seen dividing under the microscope; given a score from 1 to 3 (a lower score means fewer cells were seen dividing)
  • Tumor necrosis: How much of the tumor is made up of dying tissue; given a score from 0 to 2 (a lower score means there was less dying tissue present).

The scores for each factor are added to determine the grade for the cancer. Higher­grade cancers tend to grow and spread faster than lower­grade cancers.

GX: The grade cannot be assessed (because of incomplete information).

Grade 1 (G1): Total score of 2 or 3

Grade 2 (G2): Total score of 4 or 5

Grade 3(G3): Total score of 6 or higher Tumor (T)

T1: The sarcoma is 5 cm (2 inches) or less across

  • T1a:The tumor is superficial (near the surface of the body).
  • T1b: The tumor is deep in the limb or abdomen.

T2: The sarcoma is greater than 5 cm (2 inches) across.

  • T2a:The tumor is superficial (near the surface of the body).
  • T2b:The tumor is deep in the limb or abdomen.

Lymph nodes (N)

N0: The sarcoma has not spread to nearby lymph nodes.

N1: The sarcoma has spread to nearby lymph nodes.

Metastasis (M)

M0: No distant metastases (spread) of sarcoma are found.

M1: The sarcoma has spread to distant organs or tissues (such as the lungs).

Stage grouping for soft tissue sarcomas

To assign a stage, information about the tumor, its grade, lymph nodes, and metastasis is combined by a process called stage grouping. The stage is described by Roman numerals from I to IV and the letters A or B. The stage is useful in selecting treatment, but other factors, such as where the sarcoma is located, also influence treatment planning and outlook.

Stage IA

T1, N0, M0, G1 or GX: The tumor is not larger than 5 cm (2 inches) across (T1). It has not spread to lymph nodes (N0) or more distant sites (M0). The cancer is grade 1 (or the grade cannot be assessed).

Stage IB

T2, N0, M0, G1 or GX: The tumor is larger than 5 cm (2 inches) across (T2). It has not spread to lymph nodes (N0) or more distant sites (M0). The cancer is grade 1 (or the grade cannot be assessed).

Stage IIA

T1, N0, M0, G2 or G3: The tumor is not larger than 5 cm (2 inches) across (T1). It has not spread to lymph nodes (N0) or more distant sites (M0). The cancer is grade 2 or 3.

Stage IIB

T2, N0, M0, G2: The tumor is larger than 5 cm (2 inches) across (T2). It has not spread to lymph nodes (N0) or more distant sites (M0). The cancer is grade 2.

Stage III

Either

T2, N0, M0, G3: It is larger than 5 cm (2 inches) across (T2). It has not spread to lymph nodes (N0) or more distant sites (M0). The cancer is grade 3.

OR

Any T, N1, M0, any G: The cancer can be any size (any T) and any grade (any G). It has spread to nearby lymph nodes (N1). It has not spread to distant sites (M0).

Stage IV

Any T, Any N, M1, any G: The cancer can be any size (any T) and grade (any G). It has spread to lymph nodes near the tumor (N1) and/or to distant sites (M1).