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I. CLASSIFICATION AND APPROACH TO TREATMENT
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A. Types of soft-tissue sarcomasThe soft-tissue sarcomas are a group of diseases characterized by neoplastic proliferation of tissue of mesenchymal origin. Thus, they differ from the more common carcinomas, which arise from epithelial tissue. Sarcomas can arise in any area of the body and from any origin; however, they most commonly arise in the soft tissue of the extremities, trunk, retroperitoneum, or head and neck area. There are more than 50 different types of sarcomas, classified according to lines of differentiation toward normal tissue. For example, rhabdomyosarcoma shows evidence of skeletal muscle fibers with cross-striations, liposarcoma shows fat production, and angiosarcoma shows vessel formation, and there are several types within each of these groups. Precise characterization of the types of sarcoma is often impossible, and these tumors are called unclassified sarcomas. All of the primary bone sarcomas may arise in soft tissue, leading to such diagnoses as extraskeletal osteosarcoma, extraskeletal Ewing sarcoma, and extraskeletal chondrosarcoma. A common diagnosis in the recent past was malignant fibrous histiocytoma (MFH). This tumor is characterized by a mixture of spindle (or fibrous) cells and round (or histiocytic) cells arranged in a storiform pattern with frequent areas of pleomorphic appearance and frequent giant cells. There is no evidence of differentiation toward any particular tissue type. Many tumors previously called pleomorphic fibrosarcoma, pleomorphic rhabdomyosarcoma, and so forth were classified as MFH. As immunohistochemistry and molecular diagnostic techniques have improved, many of the tumors previously classified as MFH have been reclassified as pleomorphic something else. Furthermore, there are strong opponents of the term MFH because there is no evidence that the tumors have either fibrous or histiocytic origin, and pleomorphic tumors previously classified as MFH are frequently now referred to as unclassified high-grade pleomorphic sarcomas.
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B. MetastasesMetastatic spread of all sarcomas tends to be through the blood rather than through the lymphatic system. The lungs are by far the most frequent site of metastatic disease. Local sites of metastasis by direct invasion are the second most common area of involvement, followed by bone and liver. (Liver metastases are common with intra-abdominal sarcomas, especially gastrointestinal stromal tumors [GISTs]; however, metastases to soft tissue are common with myxoid liposarcomas.) Central nervous system (CNS) metastases are extraordinarily rare except in alveolar soft-part sarcoma.
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C. StagingStaging of sarcomas is complex and demands an expert sarcoma pathologist. Tumors have been staged according to two systems: the American Joint Committee on Cancer (AJCC) staging system and the Musculoskeletal Tumor Society staging system. The new International Union Against Cancer (UICC)/AJCC staging system, with international acceptance, takes portions from each of the older systems and more appropriately identifies patients at increased risk of metastatic disease. Further revisions to this system are still under way, and a final, widely accepted system is still not universally accepted. As current and older publications still refer to the older systems, however, all will be included.
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1. The old AJCC staging system
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a. Tumor grade. The primary determinant of stage is tumor grade. Grade 1 tumors are stage I; grade 2 tumors are stage II; and grade 3 tumors are stage III. Any tumor with lymph node metastases is automatically stage III. Any tumor with gross invasion of bone, major vessel, or major nerve is stage IV.
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b. Stage. Further divisions of stages I to III into A and B are based on tumor size.
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A: Tumor smaller than 5 cm
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B: Tumor size 5 cm or larger.
In stage III, lymph node metastases are classified as IIIC. In stage IV, local invasion is called IVA, and IVB represents distant metastases. -
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2. The Musculoskeletal Tumor Society staging system. The Musculoskeletal Tumor Society stages sarcomas according to grade and compartmental localization. The Roman numeral reflects the tumor grade.The letter reflects compartmental localization. Compartments are defined by fascial planes.
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Stage A: Intracompartmental (i.e., confined to the same softtissue compartment as the initial tumor)
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Stage B: Extracompartmental (i.e., extending outside of the initial soft-tissue compartment into the adjacent soft-tissue compartment or bone).
A stage IA tumor is a low-grade tumor confined to its initial compartment, a stage IB tumor is a low-grade tumor extending outside the initial compartment, and so forth. -
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3. The new AJCC staging system. The stage is determined by tumor grade, tumor size, and tumor location relative to the muscular fascia. There are now four tumor grades.
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Grade 1: Well differentiated
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Grade 2: Moderately differentiated
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Grade 3: Poorly differentiated
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Grade 4: Undifferentiated.
Tumor size is now divided at less than or equal to 5 cm or more than 5 cm (in the old AJCC system, it was less than 5 cm or more than or equal to 5 cm).-
T1: ≤5 cm
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T2: >5 cm.
Tumor status is subdivided by location relative to the muscular fascia.-
Ta: Superficial to the muscular fascia
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Tb: Deep to the muscular fascia.
The AJCC stage grouping is as follows.Stage I
T1a, 1b, 2a, 2b
N0
M0
G1-2
Stage II
T1a, 1b, 2a
N0
M0
G3-4
Stage III
T2b
N0
M0
G3-4
Stage IV
Any T
N1
M0
Any G
Any T
N0
M1
Any G
The new staging system divides patients according to necessary therapy.-
Stage I patients are adequately treated by surgery alone.
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Stage II patients require adjuvant radiation therapy.
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Stage III patients require adjuvant chemotherapy.
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Stage IV patients are managed primarily with chemotherapy, with or without other modalities.
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D. EvaluationPatients are evaluated and followed according to the plan in Table 16.1.TABLE 16.1 I Soft-Tissue Sarcoma Evaluation
Tests*
Initial
During Treatment
Follow-Up (If No Evidence of Disease)
History and physical examination
X
Before each treatment
Year 1: every 2 months
Years 2 and 3: every 3 months
Year 4: every 4 months
Year 5: every 6 months
Then yearly
CBC, differential, and platelet counts†
X
Twice weekly
Yearly
Electrolytes†
X
Before each treatment
—
Chemistry profile†
X
Before each treatment
Every 4 months
Urinalysis
If giving ifosfamide
As indicated by symptoms
—
PT, APTT, fibrinogen
X
—
—
Chest radiograph
X
Before each treatment
Same as for history and physical examination
CT scan chest
If chest radiograph appears normal
To confirm chest radiograph findings (if initially abnormal) or for surgical planning
If chest radiograph becomes equivocal
MRI primary (if not intraabdominal)
X
Preoperatively
—
Ultrasound primary
—
—
Year 1: every 4 months Years 2 and 3: every 6 months
PET-CT
X
Every 2-3 cycles if preoperative therapy is given
CT of abdomen and pelvis
If myxoid liposarcoma or retroperitoneal or pelvic primary tumor
If baseline, every third cycle
If baseline:
Year 1: every 4 months
Years 2 and 3: every 6 months
ECG
If cardiac history
—
—
Cardiac nuclear scan (for ejection fraction)
If cardiac history
If doxorubicin dose is to exceed standard limits for schedule
Yearly for 2 years, then as clinically indicated
Central venous catheter
X
—
—
Bone marrow or screening MRI of spine and pelvis
If small cell tumor
—
—
Bone scan
If indicated by history
—
—
Plain film
If indicated by history
APTT, activated partial thromboplastin time; CBC, complete blood count; CT, computed tomography; ECG, electrocardiogram; MRI, magnetic resonance imaging; PET, positron emission tomography; PT, prothrombin time.
* May be ordered more frequently if patient is on a medical treatment program.† Often required more frequently if patient is on a medical treatment program.
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E. Primary treatment
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1. Surgery and radiotherapy.
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Soft-Tissue Sarcomas
Soft-Tissue Sarcomas
Robert S. Benjamin