I. STAGING
Bone tumors are staged according to American Joint Committee on Cancer (AJCC) criteria as well as the criteria of the Musculoskeletal Tumor Society.
A. The AJCC staging system
The stage is determined by tumor grade, tumor size, and presence and sites of metastases. There are four tumor grades:
Grade 1: Well differentiated—low grade
Grade 2: Moderately differentiated—low grade
Grade 3: Poorly differentiated—high grade
Grade 4: Undifferentiated—high grade.
Ewing sarcoma is classified as G4.
Tumor size is divided at less than or equal to 8 cm. Tumor size determines A and B, substages of stages I and II, and stage III:
T1 = ≤8 cm
T2 = >8 cm
T3 = Discontinuous tumors in the primary bone site.
Metastatic status is subdivided by presence and location of metastases:
M0 = No distant metastases
M1 = Distant metastases
M1a = Lung
M1b = Other distant sites, including lymph nodes.
The AJCC stage grouping is as follows:
Stage IA
G1-2
T1
N0
M0
Stage IA
G1-2
T2
N0
M0
Stage IIA
G3-4
T1
N0
M0
Stage IIB
G1-2
T2
N0
M0
Stage III
Any G
T3
N0
M0
Stage IVA
Any G
Any T
N0
M1a
Stage IVB
Any G
Any T
Any N
M1b (includes N1)
B. 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:
Stage I: Low grade
Stage II: High grade
Stage III: Any-grade tumor with distant metastasis.
The companion letter reflects tumor compartmentalization.
Stage A: Confined to bone
Stage B: Extending into adjacent soft tissue.
C. Evaluation of staging
Thus, a stage IA tumor is a low-grade tumor confined to bone, and a stage IB tumor is a low-grade tumor extending into soft tissue, and so forth. Patients are evaluated and followed according to the plan in Table 17.1.
II. EWING SARCOMA
A. General considerations and aims of therapy
1. Tumor characteristics. Ewing sarcoma is a highly malignant, small, round-cell tumor of bone. Together with other members of the Ewing Family of Tumors (EFT), most notably primitive neuroectodermal tumor, Ewing sarcoma is characterized by a specific t(11;22) chromosome translocation that results most commonly in the EWS-FLI-1 gene rearrangement. It is now believed that all members of the EFT should be considered as the same tumor. It occurs most commonly in the second decade of life, and 90% of patients are younger than 30 years. There is a slight male predominance. The most common locations are the pelvis or the diaphysis of long tubular bones of the extremities. Often, systemic symptoms of fever and leukocytosis suggest infection. Radiographically, the predominant feature is osteolysis, although sclerosis does occur. Frequently, the periosteal reaction has the so-called onion skin pattern with layering of subperiosteal new bone, frequently with spicules radiating out from the cortex. Prognosis, until the era of modern chemotherapy, was extremely poor, with a 5-year survival rate lower than 10% and almost half of patients dying within 1 year of diagnosis. Because Ewing sarcoma is a high-grade tumor and, by definition, is almost always accompanied by a soft-tissue mass, it usually is staged as AJCC stage IIB or IV depending on the demonstration of metastatic disease in lung (IVA), bone (IVB), or both. Bone metastases confer a markedly worse prognosis.
TABLE 17.1 Primary Bone Sarcoma Evaluation
Tests*
Before Therapy
On Initial Treatment
Preoperative
On Subsequent Treatment
Follow-Up
History and physical examination
X
Before each treatment
X
Before each treatment
Year 1: every 2 months Years 2 and 3: every 3-4 months Year 4: every 4 months Year 5: every 6 months Then yearly
CBC, differential, and platelet counts†
X
Twice weekly
X
Twice weekly
Yearly
Chemistry profile†
X
Before each treatment
X
Before each treatment
Year 1: every 4-6 months Then yearly
Calculated creatinine clearance
X
For methotrexate
—
For methotrexate
—
Electrolytes, mg†
X
Before each treatment
X
Before each treatment
—
Urinalysis
If ifosfamide is given
As indicated by symptoms
X
Before each treatment
—
PT, APTT, fibrinogen
X
Before each IA treatment and every day while on IA treatment
X
—
—
Plain films of primary tumor
X
Every two cycles
X
Every 3 months
Year 1: every 4-6 months Then yearly
CT of primary tumor
X
After two to four cycles
X
—
At end of treatment for head and neck or pelvic primaries
MRI of primary tumor
—
For surgical planning only
—
—
Bone scan
X
PET-CT‡
X
After two to four cycles
If needed to assess response
—
—
Chest radiograph
X
Before each treatment
X
Before each treatment
Year 1: every 2 months Years 2 and 3: every 3-4 months Year 4: every 4 months Year 5: every 6 months Then yearly
Chest CT
X
If chest radiograph is equivocal, to assess response, or for surgical planning
—
If chest radiograph is equivocal, to assess response, or for surgical planning
If chest radiograph is equivocal or for surgical planning
Angiogram
—
Before each preoperative treatment
—
—
—
Bone marrow
Only for small cell tumors with metastases
—
—
—
—
ECG
If cardiac history
—
If cardiac history
—
—
Cardiac scan
If cardiac history
—
If doxorubicin dose exceeds standard limits for schedule
—
—
Central venous catheter
X
—
—
—
—
Bone tumor conference
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Bone Sarcomas
Bone Sarcomas
Robert S. Benjamin
There are four major sarcomas of bone, each differing somewhat in clinical behavior, chemotherapy responsiveness, and prognosis. All present as painful bony lesions, and all metastasize preferentially to lung and then to other bones. The prognosis of untreated sarcomas of the bone is inversely proportional to their chemotherapy responsiveness. The sarcomas are considered in order of greatest to least chemotherapeutic responsiveness: Ewing sarcoma, osteosarcoma, malignant fibrous histiocytoma of bone, and chondrosarcoma.
Response to treatment is evaluated according to the usual criteria used for solid tumors and identical to that reported in Chapter 16 for soft-tissue sarcomas. It is often difficult to assess the response of primary bone tumors to chemotherapy prior to surgery, and the response on positron emission tomography-computed tomography correlates best with pathologic tumor destruction. Magnetic resonance imaging can be very misleading. Complete resection and examination of the total specimen often are required to determine response to therapy in a primary or even a metastatic lesion and to confirm complete remission.
