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Blog, Soft Tissue Sarcoma

Soft Tissue Sarcoma-Staging, Grading, and Risk Stratification


Soft tissue sarcoma staging systems are used to describe the severity of cancer, based on the size, extent of invasion, and the spread of disease to different body parts. Staging helps to determine disease prognosis and treatment strategy.

1.STS of the Trunk, Extremities (limbs), and Retroperitoneum:

TNM is the most commonly used system for staging STSs of the trunk, extremities (limbs), and retroperitoneum by the medical community. “T” stands for “Tumor Size”, “N” for “Lymph Nodes”, and “M” for “Metastasis”. Numbers and/or letters after T (1, 2, 3, and 4), N (0 and 1), and M (0 and 1) provide more details about each of these factors.

Additionally, STS of the trunk, extremities (limbs), and retroperitoneum is graded to assess the aggressiveness of the disease. A three-tiered French Federation of Cancer Centers Sarcoma Group (FNCLCC) grade system is the most commonly used system to grade the STS. In this system, the grade of a tumor is determined with the help of 3 parameters: differentiation (appearance of cell morphology under the microscope), mitotic activity (rate of cancerous cell division), and extent of necrosis (extent of dead tissue present in the tumor mass). Each parameter is scored as follows: differentiation (1–3), mitotic activity (1–3), and necrosis (0–2), where a higher score indicates abnormal cells morphology, high rate of cell division, and presence of high amount of dead tissue, respectively. The scores are added to assign the grade to a tumor, where G1 = a score of 2 or 3; G2 = a score of 4 or 5; and G3 = a score of 6 to 8.

Once T, N, and M categories and the overall grade of a tumor are determined through different diagnostic techniques, this information is combined to assign an overall stage (from 0 to IV) to the disease. Following table describes the characteristics of different stages assigned to the STS of the trunk, extremities (limbs), and retroperitoneum:

Stage TNM & Grade Score Stage Description
Trunk & Extremities Retroperitoneum
IA T1 N0 M0 G1/X The primary tumor is </=5 cm in size. No spread to nearby lymph nodes or distant body parts. The assigned grade is G1 or grade could not be assigned or is unknown. The primary tumor is </=5 cm in size. No spread to nearby lymph nodes or distant body parts. The assigned grade is G1 or grade could not be assigned or is unknown.
IB T2-4 N0 M0 G1/X The primary tumor size may range from >5 cm to >15 cm. No spread to nearby lymph nodes or distant body parts. The assigned grade is G1 or grade could not be assigned or is unknown. The primary tumor size may range from >5 cm to >15 cm. No spread to nearby lymph nodes or distant body parts. The assigned grade is G1 or grade could not be assigned or is unknown.
II T1 N0 M0 G2-3 The primary tumor is </=5 cm in size. No spread to nearby lymph nodes or distant body parts. The assigned grade is G2 or G3. The primary tumor is </=5 cm in size. No spread to nearby lymph nodes or distant body parts. The assigned grade is G2 or G3.
IIIA T2 N0 M0 G2-3 The primary tumor is >5 cm but </=10 cm in size. No spread to nearby lymph nodes or distant body parts. The assigned grade is G2 or G3. The primary tumor is >5 cm but </=10 cm in size. No spread to nearby lymph nodes or distant body parts. The assigned grade is G2 or G3.
IIIB T3-4 N0 M0 G2-3 The primary tumor size may range from >10 cm to >15 cm. No spread to nearby lymph nodes or distant body parts. The assigned grade is G2 or G3. The primary tumor size may range from >10 cm to >15 cm. No spread to nearby lymph nodes or distant body parts. The assigned grade is G2 or G3.
Any T N1 M0 Any G N/A The primary tumor of any size. The disease has spread to nearby lymph nodes. No spread to distant body parts. The assigned grade may have any value.
IV Any T N1 M0 Any G The primary tumor of any size. The disease has spread to nearby lymph nodes. No spread to distant body parts. The assigned grade may have any value. N/A
Any T Any N M1 Any G The primary tumor of any size that might or might not have spread to nearby lymph nodes. The disease has spread to distant body parts, such as the lungs. The assigned grade may have any value. The primary tumor of any size that might or might not have spread to nearby lymph nodes. The disease has spread to distant body parts, such as the liver or lungs. The assigned grade may have any value.

 

Stage grouping for STS in the abdomen, thoracic visceral organs, and Head & neck region require further data collection and has not been established yet.

2.Gastrointestinal Stromal Tumors (GISTs):

TNM is the most commonly used system for staging GISTs by the medical community. “T” stands for “Tumor Size”, “N” for “Lymph Nodes”, and “M” for “Metastasis”. Numbers and/or letters after T (1, 2, 3, and 4), N (0 and 1), and M (0 and 1) provide more details about each of these factors.

Additionally, GIST is graded to assess the aggressiveness of the disease. The grading of GIST is based on the mitotic activity (the rate of cancerous cell division). The grade is assigned as Low or High, where Low grade means low rate of cell division. A higher grade indicates more aggressive disease and more chances of disease recurrence after treatment.

Once T, N, and M categories and the overall grade of a tumor are determined through different diagnostic techniques. This information is combined to assign an overall stage (from 0 to IV) to the disease. Following table describes the characteristics of different stages assigned to GIST of the stomach/omentum (a layer of fatty tissue covering the abdominal organs), small intestine, esophagus, colon, rectum, or peritoneum:

Stage TNM & Grade Stage Description
Stomach/Omentum Small Intestine, Esophagus, Colon, Rectum, or Peritoneum
IA T1-2 N0 M0 Low The primary tumor is </=5 cm in size. No spread to nearby lymph nodes or distant body parts. The assigned grade is Low. N/A
IB T3 N0 M0 Low The primary tumor size is >5 cm but </=10 cm. No spread to nearby lymph nodes or distant body parts. The assigned grade is Low. N/A
I T1-2 N0 M0 Low N/A The primary tumor is </=5 cm in size. No spread to nearby lymph nodes or distant body parts. The assigned grade is Low.
II T3 N0 M0 Low N/A The primary tumor size is >5 cm but </=10 cm. No spread to nearby lymph nodes or distant body parts. The assigned grade is Low.
T1-2 N0 M0 High The primary tumor is </=5 cm in size. No spread to nearby lymph nodes or distant body parts. The assigned grade is High. N/A
T4 N0 M0 Low The primary tumor size is >10 cm. No spread to nearby lymph nodes or distant body parts. The assigned grade is Low. N/A
IIIA T1 N0 M0 High N/A The primary tumor is </=2 cm in size. No spread to nearby lymph nodes or distant body parts. The assigned grade is High.
  T4 N0 M0 Low N/A The primary tumor size is >10 cm. No spread to nearby lymph nodes or distant body parts. The assigned grade is Low.
  T3 N0 M0 High The primary tumor is >5 cm but </=10 cm in size. No spread to nearby lymph nodes or distant body parts. The assigned grade is High. N/A
IIIB T4 N0 M0 High The primary tumor size is >10 cm. No spread to nearby lymph nodes or distant body parts. The assigned grade is High. N/A
T2-4 N0 M0 High N/A The primary tumor size may range from >2 cm to >10 cm. No spread to nearby lymph nodes or distant body parts. The assigned grade is High.
IV Any T N1 M0 Any G The primary tumor of any size. The disease has spread to nearby lymph nodes. No spread to distant body parts. The assigned grade may have any value. The primary tumor of any size. The disease has spread to nearby lymph nodes. No spread to distant body parts. The assigned grade may have any value.
Any T Any N M1 Any G The primary tumor of any size that might or might not have spread to nearby lymph nodes. The disease has spread to distant body parts, such as the liver. The assigned grade may have any value. The primary tumor of any size that might or might not have spread to nearby lymph nodes. The disease has spread to distant body parts, such as the liver. The assigned grade may have any value.

 

3.Rhabdomyosarcoma (RMS):

Sarcoma Committee of the Children’s Oncology Group prescribed system is mostly used for assigning a stage, clinical group, and risk group to RMS.

Staging: TNM system is used for assigning a stage to RMS. “T” stands for “Tumor Size” and invasiveness, “N” for “Lymph Nodes”, and “M” for “Metastasis”. Numbers and/or letters after T (1, 1a, 1b, 2, 2a, and 2b), N (0 and 1), and M (0 and 1) provide more details about each of these factors.

Additionally, the sites of RMS are grouped into favorable (F) and unfavorable (UF) based on the prognosis of disease at different sites. Favorable sites include Orbit (eyeball); head and neck area except the para-meningeal area (nasal passages and nearby sinuses, middle ear, and the uppermost part of the pharynx); genitourinary tract except the kidney, bladder, and prostate; and the biliary duct. All other sites are considered as unfavorable.

Once T, N, and M categories and the site of a tumor are determined through different diagnostic techniques, this information is combined to assign an overall stage (from 0 to IV) to the disease. Following table describes the characteristics of different stages assigned to RMS:

Stage Site & TNM Stage Description

 

I F; Any T, Any N, M0 The primary tumor is present at a favorable site, which may be of any size. It may or may not have invaded into a nearby tissue and/or spread to nearby lymph nodes, but has not spread to distant body parts.
II UF; T1a-2a N0 M0 The primary tumor is present at an unfavorable site, which is </=5 cm in size. It may or may not have invaded into a nearby tissue, but has not spread to nearby lymph nodes. No spread to distant body parts.
III UF; T1a-2a N1 M0 The primary tumor is present at an unfavorable site, which is </=5 cm in size. It may or may not have invaded into a nearby tissue, but has spread to nearby lymph nodes. No spread to distant body parts.
UF; T1b-2b N0 M0 The primary tumor is present at an unfavorable site, which is >5 cm in size. It may or may not have invaded into a nearby tissue and/or spread to nearby lymph nodes. No spread to distant body parts.
IV Any site; Any T Any N M1 The primary tumor is present at a favorable or an unfavorable site. It may be of any size. It may or may not have invaded into a nearby tissue and/or spread to nearby lymph nodes. It has spread to distant body parts, like the lungs, liver, bones, or bone marrow.

 

Clinical Grouping: Based on the extent of the disease and the extent of primary surgical/biopsy excision, RMS is assigned a clinical group as described in the following table:

Clinical Group Description
I A localized tumor that has been completely removed by surgery/biopsy with negative/clear margins and no sign of lymph node involvement (no cancer left behind).
II A localized tumor that has been completely removed by surgery/biopsy with a microscopic positive margin and/or sign of lymph node involvement (minor cancer left behind).
III A localized tumor that was not completely removed by surgery/biopsy with a positive margin. Sign of lymph node involvement may be present but no sign of disease spread to distant body parts.
IV The diagnosis has revealed the spread of disease to distant body parts or presence of cancer cells in the cerebral spinal fluid, pleural, or peritoneal fluids.

 

Risk Stratification: Based on the overall stage, clinical group, and type of RMS (embryonal or alveolar), a risk group is assigned to the disease. Risk group helps in selecting appropriate treatment for the disease. Following table describes the characteristics of the disease according to different risk groups:

Risk Group Description
Low risk Embryonal RMS; TNM stage 1; and Clinical groups I, II, or III

OR

Embryonal RMS; TNM stage 2 or 3; and Clinical groups I or II

Intermediate risk Embryonal RMS; TNM stage 2 or 3; and Clinical group III

OR

Alveolar RMS; TNM stage 1, 2, or 3; and Clinical groups I, II, or III

High-risk Embryonal/Alveolar RMS; TNM stage 4; and Clinical group IV

 

4.Kaposi sarcoma (KS):

No universally accepted staging system for KS is available. The AIDS Clinical Trials Group (ACTG) described risk group stratification system for Epidemic/AIDS-related KS is the most widely used grading system. This system divides Epidemic/AIDS-related KS into 2 risk groups (i.e. Good and Poor) based on the extent of disease, status of the immune system, and presence of systemic illness. Following table describes the characteristics of the 2 risk groups:

Good (Low) Risk Poor (High) Risk
Localized disease

CD4 cell count >/=150 cells/mm^3

No systemic illness present (No opportunistic infections, No B symptoms, Karnofsky performance status score >/=70)

Widespread disease

CD4 cell count <150 cells/mm^3

Systemic illness present (History of opportunistic infection, B symptoms, Karnofsky performance status score <70, or HIV-related illness, such as neurological disease or lymphoma)

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