Sarcoma

Staging

After sarcoma is diagnosed, your doctor stages the disease to determine the extent of the cancer, including where it is located and whether it has spread. This information will help your doctor recommend the most effective treatment plan.

As part of the staging process, you will likely have a number of tests and procedures. Your doctor may perform a physical examination and history and may order imaging studies, blood tests and a biopsy of the tumor and nearby lymph nodes. When examining the biopsy sample, the pathologist (a doctor who specializes in diagnosing diseases by looking at the tissue under a microscope) takes into account the number of cells that are actively dividing and how closely the cancer resembles normal tissue. The pathologist will be able to determine how fast the tumor may be growing, if the cancer is close to the surface of the skin (superficial) or deep in the body, and whether it has spread to lymph nodes or to other parts of your body. Lymph nodes are bean-shaped cells found in small collections throughout the body. They store special cells that can trap cancer cells or bacteria traveling through the body via the lymphatic system.

Your surgeon may decide to present your case at a multidisciplinary sarcoma tumor board. A tumor board is a meeting of a group of physicians who are members of the health care team involved with the treatment of sarcoma. The board will include the surgeon, medical oncologist, radiation oncologist, pathologist, radiologist, tumor registrar and other allied health personnel. This team will discuss and evaluate your case in great detail and arrive at decisions best suited to you personally.

Staging Soft Tissue Sarcomas

Soft tissue sarcomas are given a stage and grade depending on which part of the body is involved. Doctors typically use the American Joint Committee on Cancer (AJCC) TNM staging system to classify some soft tissue sarcomas, including all soft tissues of the head and neck, trunk and extremities, abdomen and thoracic organs, and the retroperitoneum (the space behind the lining of the abdomen).

The TNM system considers the size and location of the tumor (T), whether cancer cells are found in nearby lymph nodes (N) and whether the cancer has metastasized (M), or spread, to other parts of the body. The most common sites of spread are the lungs or other bones. Numbers after T, N and M provide more details for each of these factors.

The grade (G) of your cancer is associated with how rapidly the sarcoma will grow and spread, as well as with your prognosis (predicted outcome). The pathologist will examine sarcoma cells through a microscope and then assign a number to the grade according to how different these cells are from normal tissue cells, how many tumor cells are dividing and how much of the tumor has cells that are dying.

Grades are listed from low to high as GX (the grade cannot be assessed), grade 1 (G1), grade 2 (G2) and grade 3 (G3). Cells that appear healthy are called well-differentiated (denoted by a lower grade). Low-grade tumor cells look more like normal cells and are less likely to grow and spread quickly, whereas high-grade tumor cells (poorly differentiated cells) look more abnormal and tend to grow and spread faster. In general, the more differentiated the tumor, the better the prognosis.

To assign a stage, the information your doctor has gathered about the tumor, lymph nodes, metastasis and grade is combined in a process called stage grouping. The stage is described by Roman numerals from I to IV and the letters A or B.

Currently, stage groupings exist for soft tissue sarcomas of the trunk and extremities and the retroperitoneum. More data must be collected before stage groupings are defined for soft tissue sarcomas of the head and neck and the abdomen and thoracic visceral organs.

The classification and grading (along with stage groupings, when available) of soft tissue sarcomas guide doctors in determining the most appropriate treatment plan for soft tissue sarcomas of the head and neck, abdomen and thoracic visceral organs, trunk and extremities and the retroperitoneum (see tables below). Other factors, such as the location of the sarcoma, also influence treatment planning and prognosis.

Staging Bone Sarcomas

To stage bone sarcomas, doctors use many of the same imaging tests and similar physical examinations used for staging soft tissue sarcomas. The first step is to determine if the bone sarcoma is localized (seen only in the bone it started in and possibly the tissues next to the bone, such as muscle, tendon or fat) or has spread to other parts of the body. Doctors then typically use one of two preferred staging systems.

  • The AJCC TNM staging system is generally used to stage bone sarcomas. As noted earlier, this system considers the size and location of the tumor (T), whether cancer cells are found in nearby lymph nodes (N) and whether the cancer has metastasized (M) to other parts of the body. It also includes a grading system that consists of three grades.
  • The Musculoskeletal Tumor Society (MSTS) staging system, also known as the Enneking system, is based on the grade (G) of the tumor, the extent of the main (primary) tumor (T) and whether the tumor has metastasized (M) to nearby lymph nodes or other organs.

As with soft tissue sarcomas, the grade of a bone sarcoma reflects how likely it is to grow and spread, based on how it looks under the microscope. Bone sarcomas are either low grade (G1) or high grade (G2). Low-grade tumor cells look more like normal cells and are less likely to grow and spread quickly, whereas high-grade tumor cells look more abnormal and tend to grow and spread faster.

In the MSTS system, the extent of the primary tumor is classified as either intracompartmental (T1), meaning it has basically remained within the bone, or extracompartmental (T2), meaning it has extended beyond the bone into nearby structures.

Bone sarcomas that have not spread to the lymph nodes or other organs are considered M0, and those that have spread are considered M1.

These factors are combined to give an overall stage, represented by Roman numerals I, II and III. Stages I and II are further divided into A for intracompartmental tumors or B for extracompartmental tumors.

After staging, you may consider getting a second opinion from a doctor who specializes in treating the type of sarcoma you have, especially if it was difficult for your physician to stage the disease. A second opinion will confirm the diagnosis and treatment plan or add new information to consider.

Soft Tissue Sarcoma of the Head & Neck

Classification Definition
Tumor (T)
TX Primary tumor cannot be assessed.
T1 Tumor 2 cm (almost 1 inch) or less.
T2 Tumor more than 2 cm but not more than 4 cm (about 1 ½ inches).
T3 Tumor more than 4 cm.
T4
  T4a


  T4b
Tumor with invasion of adjoining structures.
Tumor with orbital invasion, skull base/dural invasion, invasion of central compartment viscera, involvement of facial skeleton or invasion of pterygoid muscles.
Tumor with brain parenchymal invasion, carotid artery encasement, prevertebral muscle invasion, or central nervous system involvement via perineural spread.
Node (N)
N0 No regional lymph node metastases or unknown lymph node status.
N1 Regional lymph node metastasis.
Metastasis (M)
M0 No distant metastasis.
M1 Distant metastasis.

 

Grade (G) Definition
GX Grade cannot be assessed.
G1 Total differentiation, mitotic count and necrosis score of 2 or 3.
G2 Total differentiation, mitotic count and necrosis score of 4 or 5.
G3 Total differentiation, mitotic count and necrosis score of 6, 7 or 8.

 

Soft Tissue Sarcoma of the Abdominal and Thoracic Visceral Organs

Classification Definition
Tumor (T)
TX Primary tumor cannot be assessed.
T1 Organ confined.
T2
  T2a
  T2b
Tumor extension into tissue beyond organ.
Invades serosa or visceral peritoneum.
Extension beyond serosa (mesentery).
T3 Invades another organ.
T4
  T4a
  T4b
  T4c
Multifocal involvement (tumors at more than 1 site).
Multifocal (2 sites).
Multifocal (3-5 sites).
Multifocal (more than 5 sites).
Node (N)
N0 No lymph node involvement or unknown lymph node status.
N1 Lymph node involvement present.
Metastasis (M)
M0 No metastasis.
M1 Metastases present.

 

Grade (G) Definition
GX Grade cannot be assessed.
G1 Total differentiation, mitotic count and necrosis score of 2 or 3.
G2 Total differentiation, mitotic count and necrosis score of 4 or 5.
G3 Total differentiation, mitotic count and necrosis score of 6, 7 or 8.

 

Soft Tissue Sarcoma of the Trunk & Extremities

Classification Definition
Tumor (T)
TX Primary tumor cannot be assessed.
T0 No evidence of primary tumor.
T1 Tumor 5 cm (almost 2 inches) or less in greatest dimension.
T2 Tumor more than 5 cm and less than or equal to 10 cm (almost 4 inches) in greatest dimension.
T3 Tumor more than 10 cm and less than or equal to 15 cm (approximately 6 inches) in greatest dimension.
T4 Tumor more than 10 cm and less than or equal to 15 cm (approximately 6 inches) in greatest dimension.
Node (N)
N0 No regional lymph node metastasis or unknown lymph node status.
N1 Regional lymph node metastasis.
Metastasis (M)
M0 No distant metastasis.
M1 Distant metastasis.

 

Grade (G) Definition
GX Grade cannot be assessed.
G1 Total differentiation, mitotic count and necrosis score of 2 or 3.
G2 Total differentiation, mitotic count and necrosis score of 4 or 5.
G3 Total differentiation, mitotic count and necrosis score of 6, 7 or 8.

 

Stage T N M G
IA T1 N0 M0 GX, G1
IB T2, T3, T4 N0 M0 GX, G1
II T1 N0 M0 G2, G3
IIIA T2 N0 M0 G2, G3
IIIB T3, T4 N0 M0 G2, G3
IV
Any T
Any T
N1
Any N
M0
M1
Any G
Any G

 

Soft Tissue Sarcoma of the Retroperitoneum

Classification Definition
Tumor (T)
TX Primary tumor cannot be assessed.
T0 No evidence of primary tumor.
T1 Tumor 5 cm (almost 2 inches) or less in greatest dimension.
T2 Tumor more than 5 cm and less than or equal to 10 cm (almost 4 inches) in greatest dimension.
T3 Tumor more than 10 cm and less than or equal to 15 cm (approximately 6 inches) in greatest dimension.
T4 Tumor more than 15 cm in greatest dimension.
Node (N)
N0 No regional lymph node metastasis or unknown lymph node status.
N1 Regional lymph node metastasis.
Metastasis (M)
M0 No distant metastasis.
M1 Distant metastasis.

 

Grade (G) Definition
GX Grade cannot be assessed.
G1 Total differentiation, mitotic count and necrosis score of 2 or 3.
G2 Total differentiation, mitotic count and necrosis score of 4 or 5.
G3 Total differentiation, mitotic count and necrosis score of 6, 7 or 8.

 

Stage T N M G
IA T1 N0 M0 GX, G1
IB T2, T3, T4 N0 M0 GX, G1
II T1 N0 M0 G2, G3
IIIA T2 N0 M0 G2, G3
IIIB
T3, T4
Any T
N0
N1
M0
M0
G2, G3
Any G
IV Any T Any N M1 Any G

Used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original and primary source for this information is the AJCC Cancer Staging Manual, Eighth Edition (2017) published by Springer Science+Business Media.

Additional Resources

 

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