Review Article - Pediatric rhabdomyosarcomas and nonrhabdomyosarcoma soft tissue sarcoma

Tumors arising from the soft tissues are uncommon in children, accounting for about 6% of all childhood malignancies. More than half (53%) of these originate from the striated muscles and are called rhabdomyosarcomas (RMS) the remaining are nonrhabdomyosarcoma soft tissue sarcomas (NRSTS). Almost two-thirds of RMS cases are diagnosed in children < 6 years of age. They can arise at varied locations like the head and neck region, genitourinary tract, extremities, trunk and retroperitoneum. Pathologically RMS is now classified as superior, intermediate and poor outcome histologies. For stratification of treatment and also comparison of results the RMS are now staged both by the clinical grouping and the TNM staging systems. The ultimate outcome depends on the site, extent of disease and histology. Currently, approximately 70% of the patients survive for 5 years or more and are probably cured. This is credited to the use of multi-modal, risk-adapted therapy, refinements in tumor grouping and better supportive care which has emerged out of cooperative studies like Intergroup Rhabdomyosarcoma Study (IRS) and the International Society of Pediatric Oncology studies (SIOP). The treatment involves chemotherapy, radiotherapy and organ/function preserving surgery. The gold standard chemotherapy is still vincristine, actinomycin D and cyclophosphamide (VAC) regime with high doses of intensity bone marrow rescue with colony stimulating factors. The NRSTS are rare and of heterogenous histologies and so it has been difficult to arrive at a treatment strategy for these. What is definitely understood is that these are usually immature and poorly differentiated tumors that respond poorly to chemotherapy and so surgical resection forms the mainstay of treatment with adjuvant radiotherapy and chemotherapy to prevent local recurrences. In all likelihood, the molecular analysis of RMS will further refine current classification schemes and knowledge of genetic features of the tumors will significantly improve the ability of investigators to identify patients at lower or higher risk of treatment failures, thus paving the way for advances in risk-based therapy.