Sarcomas are a heterogeneous group of tumors that can occur throughout the body and encompass more than 50 subtypes with distinct histologic lines of differentiation.
Approximately two-thirds of soft tissue sarcomas arise in the extremities; the remaining one-third is distributed between the retroperitoneum, trunk, abdomen, head, and neck.
Multimodality treatment, including surgical resection, radiation therapy, and, in selected cases, systemic chemotherapy, has been applied to patients with locally advanced, high-grade, extremity sarcomas.
Overall 5-year survival rate for patients with all stages of soft tissue sarcoma is 50% to 60%.
These rare tumors account for less than 1% of cancer in adults (estimated 10,000 cases per year in the United States) and represent 15% of cancers in children.
The treatment algorithm for soft tissue sarcomas depends on tumor stage, site, and histology.
Of the patients who die of sarcoma, most will succumb to metastatic disease in the lungs, which 80% of the time occurs within 2 to 3 years of the initial diagnosis.
Progress in the understanding of soft tissue sarcoma biology is crucial for the development of new treatments.
Sarcomas are a heterogeneous group of neoplasms that arise predominantly from cells of the embryonic mesoderm. While the majority of sarcomas are soft tissue sarcomas, other types of sarcoma include bone sarcomas (osteosarcoma, chondrosarcoma, and rare bone tumors like chordoma, angiosarcoma, and leiomyosarcoma of bone) and Ewing’s sarcoma/peripheral primitive neuroectodermal tumor, which can occur either in the bone or in the soft tissues. The primary focus of this chapter is soft tissue sarcomas. Most primary soft tissue sarcomas originate in an extremity (50–60%); the next most common sites are the trunk (19%), retroperitoneum (15%), and head and neck (9%). The anatomic site of a primary sarcoma influences treatment and outcome.1
Soft tissue sarcomas include more than 70 histologic subtypes (Table 36-1). Historically, the most common subtypes in adults (excluding Kaposi’s sarcoma) were malignant fibrous histiocytoma (28%), liposarcoma (15%), leiomyosarcoma (12%), synovial sarcoma (10%), and malignant peripheral nerve sheath tumor (6%).2 Today, malignant fibrous histiocytoma is classified as either leiomyosarcoma, pleomorphic undifferentiated sarcoma, myxofibrosarcoma, or dedifferentiated liposarcoma based on cellular differentiation and genetics. Embryonal/alveolar rhabdomyosarcomas are the most common soft tissue sarcomas of childhood, whereas pleomorphic rhabdomyosarcoma occurs predominantly in adults, and although it shares part of the name, it has a different biology and should not be treated as a pediatric sarcoma.
Table 36-1Relative frequency of histologic subtypes of soft tissue sarcoma ||Download (.pdf) Table 36-1 Relative frequency of histologic subtypes of soft tissue sarcoma
|HISTOLOGIC SUBTYPES ||NO. ||% |
|Liposarcoma ||188 ||15 |
|Leiomyosarcoma ||148 ||12 |
|Unclassified sarcoma ||140 ||11 |
|Synovial sarcoma ||125 ||10 |
|Malignant peripheral nerve sheath tumor ||72 ||6 |
|Rhabdomyosarcoma ||60 ||5 |
|Fibrosarcoma ||38 ||3 |
|Ewing sarcoma ||25 ||2 |
|Angiosarcoma ||25 ||2 |
|Osteosarcoma ||14 ||1 |
|Epithelioid sarcoma ||14 ||1 |