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Journal of Clinical Oncology, Vol 24, No 12 (April 20), 2006: pp. 1958-1959 © 2006 American Society of Clinical Oncology. DOI: 10.1200/JCO.2005.05.4957
Childhood Nonrhabdomyosarcoma Soft Tissue Sarcomas Are Not Adult-Type TumorsDepartment of Hematology-Oncology, St Jude Children's Research Hospital, and Department of Pediatrics, University of Tennessee College of Medicine, Memphis, TN
Department of Pediatrics, Hospital for Sick Children, Toronto, Ontario To the Editor: In the June 20, 2005, issue of the Journal of Clinical Oncology, the article by Ferrari et al1 and the accompanying Editorial by Baker2 suggest that childhood soft tissue sarcomas other than rhabdomyosarcoma be called adult-type soft tissue sarcomas rather than nonrhabdomyosarcoma soft tissue sarcomas (NRSTS).3,4 Although rhabdomyosarcoma is the most common soft tissue sarcoma (STS) in childhood, the soft tissue tumors other than rhabdomyosarcoma collectively account for more than half of STSs in children. Perhaps because children with these tumors are often treated as adults with the same diseases, the term adult-type soft tissue sarcoma has evolved to describe these pediatric tumors. However, this terminology fails to reflect important epidemiologic differences between pediatric and adult STS that have therapeutic implications. The distribution of STS differs significantly between children and adults. We reviewed data from 1993 through 2002 in the Surveillance, Epidemiology and End Results database, a population-based registry covering approximately 14% of the US population, to identify the 10 most common subtypes of STS in children and in adults (Table 1). Only five of 10 entities were common to both children and adults. Even among the 10 histologic subtypes most common in both populations, the proportion of affected patients often markedly differs. Leiomyosarcoma, for example, accounts for 13.7% of STS in adults but only 1.8% of STS in children. Kaposi sarcoma, leiomyosarcoma, and malignant fibrous histiocytoma account collectively for approximately 51% of STS in adults, whereas those subtypes make up only 7.4% of pediatric STS. Nor are differences in the distribution of STS restricted to the most common entities. The proportion of adults with endometrial stromal sarcoma is 24.5 times greater than the proportion of children with the same disease, whereas angiomatoid fibrous histiocytoma is proportionally 24.1 times greater in children as in adults. Also proportionally more common in children are embryonal sarcoma (72.2 times), clear cell sarcoma of the kidney (25.3 times), mesenchymal chondrosarcoma (8.9 times), desmoplastic small round cell tumor (7.2 times), alveolar soft part sarcoma (7 times), and clear cell sarcoma arising outside of the kidney (6 times). In addition, certain entities, such as infantile fibrosarcoma, are unique to pediatric populations.
Recently published data on STS in adults and children also support a different distribution of STS in pediatric and adult populations. In the largest published series of pediatric patients with NRSTS, synovial sarcoma and malignant peripheral nerve sheath tumor were consistently among the top three diagnoses.1,3-7 It is more difficult to find series of unselected adults with STS, but liposarcoma, malignant fibrous histiocytoma, and leiomyosarcoma are routinely among the top five, in large series of adults with extremity and retroperitoneal primary tumors.8-10 Some may question the importance of the precise terminology used to describe childhood soft tissue sarcomas other than rhabdomyosarcoma. We argue, however, that the terminology should accurately reflect the epidemiologic characteristics of these neoplasms, rather than categorizing them as adult-type tumors in children. Although considerable similarities likely exist, prospective data about prognostic factors, therapeutic responsiveness, and outcomes in pediatric patients are presently limited. Certain relatively chemosensitive subtypes (eg, synovial sarcoma) account for a significantly higher proportion of STS in pediatric populations, and such differences must be taken into account in defining a therapeutic strategy. Data about the biology of these tumors in childhood are also lacking; therefore, it is unclear whether they are biologically identical in pediatric and adult populations. Because growth and development are important factors in children, treatment considerations in childhood differ from those in adults. For these reasons, although Baker reports that medical oncologists "giggle snidely at the phrase," we believe that the term NRSTS is the most accurate and appropriate descriptor for this group of diseases in childhood, and we suggest that most thoughtful medical oncologists would agree. It is hoped that someday STS will no longer be considered a single disease entity, and that such awkward terminology will no longer be necessary. The forthcoming pediatric NRSTS clinical trials of the Children's Oncology Group and the European Pediatric Soft Tissue Sarcoma Study Group are an encouraging sign. These studies will certainly provide valuable new information about childhood NRSTS and will hopefully give rise to future histology-specific trials. Authors' Disclosures of Potential Conflicts of Interest The authors indicated no potential conflicts of interest.
ACKNOWLEDGMENTS The authors gratefully acknowledge Lynn Ries, MS, for her assistance with Surveillance, Epidemiology and End Results data retrieval and analysis. REFERENCES
1. Ferrari A, Casanova M, Collini P, et al: Adult-type soft tissue sarcomas in pediatric-age patients: Experience at the Istituto Nazionale Tumori in Milan. J Clin Oncol 23:4021-4030, 2005 2. Baker LH: Medical and pediatric oncology, not adult and pediatric oncology. J Clin Oncol 23:4003-4005, 2005 3. Spunt SL, Hill DA, Motosue AM, et al: Clinical features and outcome of initially unresected nonmetastatic pediatric nonrhabdomyosarcoma soft tissue sarcoma. J Clin Oncol 20:3225-3235, 2002 4. Spunt SL, Poquette CA, Hurt YS, et al: Prognostic factors for children and adolescents with surgically resected nonrhabdomyosarcoma soft tissue sarcoma: An analysis of 121 patients treated at St Jude Children's Research Hospital. J Clin Oncol 17:3697-3705, 1999 5. Pappo AS, Rao BN, Jenkins JJ, et al: Metastatic nonrhabdomyosarcomatous soft-tissue sarcomas in children and adolescents: The St. Jude Children's Research Hospital experience. Med Pediatr Oncol 33:76-82, 1999[CrossRef][Medline] 6. Pratt CB, Maurer HM, Gieser P, et al: Treatment of unresectable or metastatic pediatric soft tissue sarcomas with surgery, irradiation, and chemotherapy: A Pediatric Oncology Group study. Med Pediatr Oncol 30:201-209, 1998[CrossRef][Medline] 7. Pratt CB, Pappo AS, Gieser P, et al: Role of adjuvant chemotherapy in the treatment of surgically resected pediatric nonrhabdomyosarcomatous soft tissue sarcomas: A Pediatric Oncology Group Study. J Clin Oncol 17:1219, 1999 8. Pisters PW, Leung DH, Woodruff J, et al: Analysis of prognostic factors in 1,041 patients with localized soft tissue sarcomas of the extremities. J Clin Oncol 14:1679-1689, 1996 9. Pisters PW, Patel SR, Prieto VG, et al: Phase I trial of preoperative doxorubicin-based concurrent chemoradiation and surgical resection for localized extremity and body wall soft tissue sarcomas. J Clin Oncol 22:3375-3380, 2004 10. Wendtner CM, Abdel-Rahman S, Krych M, et al: Response to neoadjuvant chemotherapy combined with regional hyperthermia predicts long-term survival for adult patients with retroperitoneal and visceral high-risk soft tissue sarcomas. J Clin Oncol 20:3156-3164, 2002
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Copyright © 2006 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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