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Osteosarcoma and Malignant Fibrous Histiocytoma of Bone Treatment (PDQ®): Treatment - Health Professional Information [NCI] - Staging and Site Information

Historically, the Enneking staging system for skeletal malignancies was widely used.[1] This system inferred the aggressiveness of the primary tumor by the descriptors intracompartmental or extracompartmental. The American Joint Committee on Cancer (AJCC) staging system for malignant bone tumors has updated this staging system, substituting compartmentalization with size (see Table 2).[2] The AJCC classification is as follows:

Table 2. Definitions of TNM Stage I through Stage IVa

StageTumor GradeTumor Size
a Reprinted with permission from AJCC: Bone. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 281-90.
b Skip metastases: discontinuous tumors in the primary bone site.
IALow<8 cm
IBLow>8 cm
IIAHigh<8 cm
IIBHigh>8 cm
IIIAny tumor grade, skip metastasesb
IVAny tumor grade, any tumor size, distant metastases

For the purposes of treatment, there are only two stages of high-grade osteosarcoma. Patients without clinically detectable metastatic disease are considered to have localized osteosarcoma. Patients in whom it is possible to detect any site of metastasis at the time of initial presentation by routine clinical studies are considered to have metastatic osteosarcoma.

For patients with confirmed osteosarcoma, in addition to plain x-rays of the primary site that include a single plane view of the entire affected extremity to assess for skip metastasis, pretreatment staging studies should include magnetic resonance imaging (MRI) and/or computed tomography (CT) scan of the primary site. Additional pretreatment staging studies should include bone scan, postero-anterior and lateral chest x-ray, and CT scan of the chest. Positron emission tomography (PET) using fluorine-18-fluorodeoxyglucose is an optional staging modality.[3]

Localized Osteosarcoma

Localized tumors are limited to the bone of origin. Patients with skip lesions confined to the bone which includes the primary tumor should be considered to have localized disease if the skip lesions can be included in the planned surgical resection.[4] Approximately one-half of the tumors arise in the femur; of these, 80% are in the distal femur. Other primary sites in descending order of frequency are the proximal tibia, proximal humerus, pelvis, jaw, fibula, and ribs.[5] Compared with osteosarcoma of the appendicular skeleton, osteosarcoma of the head and neck is more likely to be low grade [6] and to arise in older patients.

Metastatic Osteosarcoma

Radiologic evidence of metastatic tumor deposits in the lungs, other bones, or other distant sites is found in approximately 20% of patients at diagnosis, with 85% to 90% of metastatic disease presenting in the lungs. The second most common site of metastasis is another bone.[7] Metastasis to other bones may be solitary or multiple. The syndrome of multifocal osteosarcoma refers to a presentation with multiple foci of osteosarcoma without a clear primary tumor, often with symmetrical metaphyseal involvement. Multifocal osteosarcoma has an extremely grave prognosis.[5]

References:

  1. Enneking WF: A system of staging musculoskeletal neoplasms. Clin Orthop Relat Res (204): 9-24, 1986.
  2. Edge SB, Byrd DR, Compton CC, et al., eds.: Bone. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 281-90.
  3. Meyer JS, Nadel HR, Marina N, et al.: Imaging guidelines for children with Ewing sarcoma and osteosarcoma: a report from the Children's Oncology Group Bone Tumor Committee. Pediatr Blood Cancer 51 (2): 163-70, 2008.
  4. Kager L, Zoubek A, Kastner U, et al.: Skip metastases in osteosarcoma: experience of the Cooperative Osteosarcoma Study Group. J Clin Oncol 24 (10): 1535-41, 2006.
  5. Longhi A, Fabbri N, Donati D, et al.: Neoadjuvant chemotherapy for patients with synchronous multifocal osteosarcoma: results in eleven cases. J Chemother 13 (3): 324-30, 2001.
  6. Patel SG, Meyers P, Huvos AG, et al.: Improved outcomes in patients with osteogenic sarcoma of the head and neck. Cancer 95 (7): 1495-503, 2002.
  7. Harris MB, Gieser P, Goorin AM, et al.: Treatment of metastatic osteosarcoma at diagnosis: a Pediatric Oncology Group Study. J Clin Oncol 16 (11): 3641-8, 1998.
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Last Updated: February 25, 2014
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