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Key Points

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  1. Nonrhadomyosarcomas are a heterogeneous group of soft tissue tumors that comprise 4% of all childhood malignancies.

  2. Degree of surgical resection and age are important prognostic variables.

  3. NRSTSs are relatively chemo-insensitive.

  4. Synovial sarcoma and malignant peripheral nerve sheath tumors are the most common pediatric NRSTS.

  5. Surgical resection is the mainstay of successful treatment of malignant peripheral nerve sheath tumors.

  6. Radiotherapy may be indicated in the setting of positive surgical margins.

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Background and Overview

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Approximately 8% of childhood malignancies are soft tissue sarcomas. Half of these are nonrhabdomyosarcoma soft tissue sarcomas NRSTS. There are over 50 histologic types and genetic patterns are poorly understood. When surgical resection is feasible, about 60% of patients are expected to achieve long-term survival with or without radiation therapy. Patient outcome is largely based on age, the presence of metastasis at diagnosis, and size and depth of the lesion. Here we focus on the most common primary histologies and differences in presentation and surgical treatment of childhood NRSTS and other common pediatric soft tissue tumors.

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The treatment for children and adolescents with NRSTS has not previously been standardized, nor have there been any pediatric cooperative group trials as in rhabdomyosarcoma (RMS). Because there are many histological subtypes of NRSTS, standardization of treatment is difficult. The first risk-based prospective trial of NRSTS in children and adolescents is completing soon. In this trial patients with NRSTS are treated as low-, intermediate-, or high-risk based on criteria previously ascertained in a thorough review of 121 patients by Spunt. In patients with surgically resected NRSTS, univariate analysis revealed clear risk factors. Positive surgical margins (p = 0.004), tumor size greater than or equal to 5 cm (p < 0.001), invasiveness (p = 0.002), high-grade (p = 0.028), and intra-abdominal primary site (p = 0.055) had a negative impact on event free survival EFS. Multivariate analysis verified all of these risk factors except for invasiveness. Local recurrence was predicted by intra-abdominal primary site (p = 0.028), positive surgical margins (p = 0.003), and the omission of radiation therapy (0.043). As expected, the biology of the tumor, that is tumor size >5 cm, invasiveness, and high grade, predicted distant recurrences. Children and adolescents with initially unresectable NRSTS are a subgroup of pediatric NRSTS that are particularly high risk. These are large tumors, greater than 5 cm, which involve critical neurovascular structures of the extremity, trunk, abdomen, or pelvis. In these patients, the 5-year estimated overall survival and EFS were 56% and 33%, respectively and post relapse survival was poor, 19% despite multimodality therapy.

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In addition to unresectability, age is a prognostic indicator in pediatric NRSTS. Patients less than 1 year of age have an excellent prognosis whereas, the adolescents and young adults have the worse prognosis compared to younger patients or older adults. A 34-year review of patients treated at St Jude Children's Research Hospital, (SJCRH) revealed the ...

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