Purpose: To identify risk factors associated with outcome in children with metastatic rhabdomyosarcoma in a large cohort of patients Patients and Methods: Pooled data were obtained from 788 patients treated in nine studies performed by European and American cooperative groups. Clinical factors, including age, histology, site of primary, and site(s) and number of sites of metastatic disease, were correlated with event-free survival (EFS) and overall survival (OS). Results: Seven hundred eighty-eight patients were eligible for analysis. The 3-year OS and EFS were 34% (SE, 1.7) and 27% (SE, 1.6), respectively. By univariate analysis, 3-year EFS was significantly and adversely influenced by age, alveolar histology, location of primary tumor in unfavorable site (defined as extremity and “other” sites), presence of three or more sites of metastatic disease, and the presence of bone or bone marrow involvement. By multivariate analysis, EFS was strongly correlated to all factors except histology. Relative risks were 1.6 for age younger than 1 year or at least 10 years, 1.4 for unfavorable site of primary tumor, 1.4 for bone or bone marrow involvement, 1.4 for three or more metastatic sites. EFS was 50% for patients without any of these four adverse factors and was respectively 42%, 18%, 12%, and 5% in patients with one, two, three, or four factors (P < .0001). Conclusion: This analysis identified subsets of patients with metastatic rhabdomyosaroma with different outcomes to current therapy and offers a strategy to define patient candidates for experimental approaches to treatment.

Purpose: To assess the value of chemotherapy and radiotherapy in children with malignant peripheral nerve sheath tumors (MPNSTs) and to identify risk factors associated with outcome. Patients and Methods: A total of 167 untreated eligible patients enrolled onto the Italian and German studies between 1975 and 1998 entered this analysis. Seventeen percent of patients had neurofibromatosis type 1 (NF1). Chemotherapy was administered to 74% of patients; radiotherapy was administered to 38% of patients. Results: With a median follow-up of 7 years, 5-year overall survival (OS) and progression-free survival (PFS) were 51% and 37%, respectively. The 5-year OS and PFS by Intergroup Rhabdomyosarcoma Study (IRS) groupings were as follows: group I, 82% and 61%; group II, 62% and 37%; group III, 32% and 27%; group IV, 26% and 21%, respectively. Univariate analysis identified IRS groups, size, invasiveness, primary site, age, and presence of NF1 as prognostic factors; multivariate analysis identified absence of NF1, tumor invasiveness T1, IRS groups I to II and extremity of primary site as independent favorable factors for OS. A trend was observed toward a benefit from radiotherapy after initial gross resection. The overall response rate to primary chemotherapy, including minor responses, in group III patients was 45%. Conclusion: MPNST is an aggressive tumor for which complete surgical resection is the mainstay of successful treatment. Postoperative radiotherapy may have a role in improving local control in patients with minimal residual tumor. The reported responses to primary chemotherapy suggest that it may be effective in patients with tumor considered unresectable at diagnosis.

Sclerosing rhabdomyosarcoma (ScRMS) and spindle cell rhabdomyosarcoma (SRMS) have been recently reclassified as a stand-alone pathologic entity, separate from embryonal RMS. Genetically, a subset of the congenital cases display NCOA2 gene rearrangements, whereas tumors occurring in older children or adults harbor MYOD1 gene mutations with or without coexisting PIK3CA mutations. Despite these recent advances, a significant number of tumors lack known genetic alterations. In this study we sought to investigate a large group of pediatric SRMS/ScRMS, spanning a diverse clinical and pathologic spectrum, by using a combined fluorescence in situ hybridization, targeted DNA, and whole-transcriptome sequencing methodology for a more definitive molecular classification. A total of 26 SRMS and ScRMS cases were selected from the 2 participating institutions for the molecular analysis. Ten of the 11 congenital/infantile SRMS showed recurrent fusion genes: with novel VGLL2 rearrangements seen in 7 (63%), including VGLL2-CITED2 fusion in 4 and VGLL2-NCOA2 in 2 cases. Three (27%) cases harbored the previously described NCOA2 gene fusions, including TEAD1-NCOA2 in 2 and SRF-NCOA2 in 1. All fusion-positive congenital/infantile SRMS patients with available long-term follow-up were alive and well, none developing distant metastases. Among the remaining 15 SRMS patients older than 1 year, 10 (67%) showed MYOD1 L122R mutations, most of them following a fatal outcome despite an aggressive multimodality treatment. All 4 cases harboring coexisting MYOD1/PIK3CA mutations shared sclerosing morphology. All 5 fusion/mutation-negative SRMS cases presented as intra-abdominal or paratesticular lesions.

Purpose: To retrospectively analyze the clinical features and results of treatment in 56 infants with fibrosarcoma enrolled onto cooperative European protocols between 1979 and 2005 and treated with a combination of surgery and chemotherapy. Patients and Methods: We performed a retrospective case review of infants under the age of 2 years with fibrosarcoma treated between 1979 and 2005 in six European studies. Patients were staged according to the Intergroup Rhabdomyosarcoma Staging System international classification as a function of the type of initial surgery and the extent of disease and were treated with surgery and chemotherapy. Survival was calculated using the Kaplan-Meier method. Results: Primary tumor site was the limbs in 66% of patients; median tumor diameter was more than 5 cm in 63% of patients; and postoperative staging was as follows: group I, 22%; group II, 27%; group III, 47%; and group IV, 4%. Response rate to chemotherapy was 75%, and the specific response rate to vincristine-dactinomycin was 71%. Local control was obtained in 84% of patients. At the end of follow-up, 45% of survivors had been treated by surgery alone, 6% by chemotherapy alone, 46% by surgery and chemotherapy, and 2% by surgery, chemotherapy, and radiotherapy. The 5-year overall survival (OS) rate was 89%. The 5-year OS and event-free survival rates for localized patients were 89% and 81%, respectively. Conclusion: Although complete resection is rarely feasible at diagnosis, conservative surgery remains the mainstay treatment for infantile fibrosarcoma. An alkylating agent–free and anthracycline-free regimen is usually effective and should be chosen as first-line chemotherapy for inoperable tumors. Overall prognosis is good, but progression or relapse, mainly local, remains possible.