Fusion transcripts as liquid biopsy markers in alveolar rhabdomyosarcoma and synovial sarcoma: A report of the Cooperative Weichteilsarkom Studiengruppe (CWS).

BACKGROUND: The possible application of gene fusion transcripts as tumor-specific noninvasive liquid biopsy biomarkers was investigated in blood plasma from patients with alveolar rhabdomyosarcoma (ARMS) and synovial sarcoma (SS). METHODS: Patients entered in the CWS Soft-Tissue Sarcoma Registry (SoTiSaR) with tumors positive for fusion genes and available blood/plasma samples were included in our analysis. Cell-free exosomal RNA was extracted and used to detect PAX-FOXO1 or SYT-SSX fusion transcripts by reverse transcription quantitative PCR (RT-qPCR). RESULTS: The analysis included 112 ethylene diamine tetraacetic acid blood samples from 80 patients (65 with ARMS, 15 with SS; 34 with localized, 46 with metastatic disease). For patients with metastatic ARMS, 62% (n = 18) of initial liquid biopsies were positive, and 16 (89%) of them showed initial bone marrow (BM) metastases. For all patients with primary localized ARMS, liquid biopsy was negative at diagnosis. Of the 48 plasma samples collected during therapy and follow-up, five were positive. None of the liquid biopsies from patients with SS were positive. CONCLUSIONS: This liquid biopsy assay based on the detection of fusion transcripts in cell-free RNA from blood exosomes is suitable for analysis of patients with ARMS. Results showed good correlation with the initial tumor status; liquid biopsy was positive in 94% of patients with metastatic ARMS and initial BM involvement, whereas biopsies from all patients with localized tumors were negative. Prospective validation and optimization of the assay, as well as its application for other markers in diagnostics and monitoring of soft-tissue sarcoma, are ongoing.

Dermatofibrosarcoma protuberans in children and adolescents: Primary and Relapsed disease-Experience of the Cooperative Weichteilsarkomstudiengruppe (CWS).

BACKGROUND: Dermatofibrosarcoma protuberans (DFSP) is a rare low-grade tumor. Little is known about best treatment of primary and relapsed disease (RD). METHODS: Treatment and outcome of 40 patients with DFSP prospectively registered within the CWS-96 and -2002P trials and the registry SoTiSaR (1996-2016) were analysed. RESULTS: Median age was 8 years (range, 0.64-17.77). Fluorescence in situ hybridization analysis to detect COL1A1-PDGFB fusion genes was positive in 86% (12/14) of evaluated patients. Primary resection was performed in all patients. Patients had IRS group I (n = 28), II (n = 9), and III (n = 2); not available (n = 1). To achieve complete remission (CR), a secondary resection was performed in 18 patients resulting in microscopically complete (R0, n = 34/40) and microscopically incomplete (R1, n = 5/40) resection. All patients achieved CR. The 5-year event-free survival (EFS) and overall survival was 86% (±12; CI, 95%) and 100% (±0; CI, 95%), respectively. R0 resection/IRS I was significantly favorable for the 5-year EFS. Local relapse occurred after a median time of 1.1 years (range, 0.04-5.1) in 15% (6/40) after CR. All patients with RD underwent resection and achieved CR. Three patients had fibrosarcomatous DFSP, two were alive after R0 resection. CONCLUSION: Complete surgical resection is mandatory to prevent relapse of DFSP.

Localized synovial sarcoma of the foot or ankle: A series of 32 Cooperative Weichteilsarkom Study Group patients.

BACKGROUND: Synovial sarcoma of the foot/ankle is rare. Mutilating surgery is often discussed. METHODS: Patients registered from 1981 to 2013 were analyzed. Cooperative Weichteilsarkom Studiengruppe (CWS) protocols recommend chemotherapy for all synovial sarcoma patients. RESULTS: Thirty-two of 330 patients with localized synovial sarcoma had their tumor at the foot/ankle. Eleven of thirty-two tumors were >5 cm. Twenty were T1, 11 T2, and one TX, respectively. Eight (25%) patients underwent primary complete resection with free margins (Intergroup Rhabdomyosarcoma Study [IRS] I), 12 of 32 (38%) primary complete resection with positive margins (IRS II), and 12 of 32 (38%) had macroscopic residuals (IRS III). The best surgical result at any time was R0 in 19, R1 in 10 and R2 in one patient, and missing in two. Mutilation was documented in 14 of 32 (44%). Radiotherapy was conducted in 20 patients. All patients achieved a first complete remission. Five-year-event-free survival and overall survival rates were 80% and 86%, respectively. Four patients suffered local and four other metastatic recurrences. IRS and the best surgical result at any time did not correlate with survival. There was no prognostic difference between R0- and R1-resection. CONCLUSION: Survival expectancies for patients with localized synovial sarcomas of the foot/ankle compare favorably to that of those with other affected sites. DISCUSSION: Further studies are needed to set the limits of minimally required aggressiveness of local therapies.

Inflammatory myofibroblastic tumors-A retrospective analysis of the Cooperative Weichteilsarkom Studiengruppe.

BACKGROUND: Inflammatory myofibroblastic tumors (IMTs) are a rare subgroup of soft tissue tumors. The outcome of patients with IMT has been reported as favorable when the tumor is completely resected. If surgical resection is not possible, systemic therapy has to be considered. However, the best systemic treatment and response rates are currently unclear. METHODS: Thirty-eight patients under the age of 21, who were registered between 2000 and 2014 with a primary diagnosis of IMT, were analyzed. RESULTS: IMT was typically localized intra-abdominally or in the pelvis. In 20 patients, the tumor was resected without further therapy; 17 patients were in complete remission at last evaluation and two patients were in partial remission. Eighteen patients received systemic therapy, 15 of whom had macroscopically incomplete resection. Systemic therapy most commonly consisted of regimens with dactinomycin, ifosfamide or cyclophosphamide, and vincristine, with or without doxorubicin, and it seemed to reduce tumor extension in individual cases. Five-year event-free survival was 74 ± 14% and 5-year overall survival was 91 ± 10% for all patients. The patients who died due to the disease were those with incomplete resection (n = 3). CONCLUSIONS: Surgery without further systemic therapy was a feasible and acceptable therapeutic option for every second patient with IMT. Standard chemotherapy for pediatric soft tissue sarcoma produced favorable results in individual cases and was able to shrink the tumor enough to enable resection. Superior efficacy of new targeted therapies such as anaplastic lymphoma kinase-inhibitors compared to standard chemotherapy has to be proven in the future.

Importance of whole-body imaging with complete coverage of hands and feet in alveolar rhabdomyosarcoma staging.

BACKGROUND: Alveolar rhabdomyosarcoma commonly arises in the extremities and is characterized by aggressive biology and high frequency of metastases. Whole-body imaging is increasingly employed in pediatric oncology but not recommended as standard in the staging of soft-tissue sarcomas. OBJECTIVE: After observing patients with a large symptomatic alveolar rhabdomyosarcoma lesion and a smaller silent lesion in the more distal part of an extremity we sought to estimate the frequency of this constellation. MATERIALS AND METHODS: We retrospectively evaluated the data of prospectively registered paediatric patients (age <21 years) with alveolar rhabdomyosarcoma in the SoTiSaR (Soft Tissue Sarcoma Registry) of the Cooperative Weichteilsarkom Studiengruppe (CWS) 09/2011-04/2015 with regard to whole-body imaging. RESULTS: Seventy-five patients were eligible. Images of 57 patients had been submitted for reference consultation, including 80 whole-body examinations in 36 patients. Among them were 5 patients (14%, 95% confidence interval 3-25%) who had been diagnosed because of a symptomatic lesion while an additional silent lesion in the distal part of an extremity had remained unnoticed and had only been detected by later whole-body imaging. It is noteworthy that in 42 (53%) of all 80 whole-body examinations, the hands and feet had been only partially covered or completely excluded. CONCLUSION: In alveolar rhabdomyosarcoma silent lesions can be overlooked when the distal parts of the limbs are not thoroughly examined and not completely covered by imaging. Missing them influences treatment decisions and prognosis. Our results should be considered when evaluating the potential role of whole-body imaging in rhabdomyosarcoma.

Tumour volume reduction after neoadjuvant chemotherapy impacts outcome in localised embryonal rhabdomyosarcoma.

BACKGROUND: Response (tumour volume reduction) to induction chemotherapy has been used to stratify secondary local and systemic treatment of Intergroup Rhabdomyosarcoma Study Group III (IRSG-III) embryonal rhabdomyosarcoma (RME) in consecutive CWS-trials. To evaluate its actual impact we studied response-related treatment and outcomes. PROCEDURE: Patients with IRSG-III RME <21 years and non-response (NR, <33% volume reduction) in five consecutive CWS-trials were analysed and compared with partial responders (PAR, ≥ 33% reduction). The NR was reviewed and sub-classified as Objective Response (OR, <0%-33% reduction) or Stable/Progressive Disease (SPD). RESULTS: Fifty-nine of 529 patients had NR (n = 34 OR, n = 25 SPD). Primary risk-factors including age, tumour size, and TN-classification did not differ between NR and PAR groups but NR had more patients with unfavourable sites comparatively (P = 0.04). There were no differences in primary risk-factors between OR and SPD. Significant factors associated with poor outcome in multivariate analysis were NR, TN-classification, age >10 years, tumour size >5 cm and therapy in older trials. After response assessment n = 24 NR continued to receive induction chemotherapy, n = 32 received other combinations and n = 3 no further chemotherapy. Forty-two non-responders were irradiated, and the tumours were completely resected in n = 20. After a median follow-up of 8 years, 34 NR are alive. Seventeen of 21 failures leading to disease-related deaths were locoregional. The five-year overall survival rate (OS) was 76 ± 4% for PAR, 79 ± 14% for OR, but only 40 ± 19% for SPD (P < 0.001). CONCLUSION: Response to induction chemotherapy appears to be an important surrogate marker of poor outcome in patients with SPD largely due to ineffective local control.

Challenges in the local treatment of large abdominal embryonal rhabdomyosarcoma.

BACKGROUND: Embryonal rhabdomyosarcoma is the most common pediatric soft tissue sarcoma. The best local treatment in large, nonmetastatic primary unresected nongenitourinary embryonal rhabdomyosarcoma of the abdomen (LARME) is however unclear. METHODS: We analyzed patients with LARME treated in four consecutive CWS trials. All diagnoses were confirmed by reference reviews. Treatment included multiagent chemotherapy and local treatment of the primary tumor with surgery and/or radiotherapy. The impact of primary debulking surgery (PDS) also was studied. RESULTS: One hundred patients <21 years with a median age of 4 years had LARME. Sixty-one of them had a tumor >10 cm in diameter at diagnosis. PDS was performed in 19 of 100 children. The outcomes of patients with PDS were similar to those of the other patients. In 36 children, the tumor was resected after induction chemotherapy; 60 RME were irradiated. The toxic effects of radiochemotherapy were not significantly increased compared with the nonirradiated patients. With a median follow-up of 10 years, the 5-year EFS and OS were 52 ± 10 and 65 ± 9 %, respectively. Significant risk factors in multivariate analysis were age >10 years; no achievement of complete remission; and inadequate secondary local treatment, defined as incomplete secondary resection or no radiation. CONCLUSIONS: Children with LARME have a fair prognosis, despite an often huge tumor size and unfavorable primary site, if the tumors can either be resected or irradiated following induction chemotherapy. PDS was only performed in a small subgroup. Radiation performed concomitantly with chemotherapy did not increase the acute toxicity significantly.

Synovial sarcoma disease characteristics and primary tumor sites differ between patient age groups: a report of the Cooperative Weichteilsarkom Studiengruppe (CWS).

BACKGROUND: Older age is associated with worse outcome in synovial sarcoma (SS) patients. Differences in disease presentation among distinct age groups, however, are currently unknown. METHODS: SS patients < 21 years registered in consecutive CWS trials over the period of 1981-2018 were evaluated. Characteristics were analyzed according to age groups using the Fisher's exact test. RESULTS: The study population included 432 SS patients. Disease characteristics differed according to age groups of children (0-12 years, n = 176), adolescents (13-16 years, n = 178), and young adults (17-21 years, n = 78). The proportion of invasive tumors (T2) was significantly higher in older patients: children 33%, adolescents 39% and young adults 54%, p = 0.009805. Similarly, the proportion of tumors > 10 cm was higher (13%, 21%, 31%; p = 0.005657) whereas conversely, the proportion of small tumors < 3 cm was lower in older patients (29%, 24%, 6%; p = 0.000104). The presence of metastases at first diagnosis was also highest in older patients (6%, 10%, 21%, p = 0.000963). Notably, the proportion of thigh tumors was higher in older patients (p = 0.04173), whereas the proportion of head-neck tumors was lower in older patients (p = 0.08896). CONCLUSIONS: The rates of large, invasive tumors and the presence of metastases are significantly associated with older patient age. Localization to the thigh is more frequent in older patients. DISCUSSION: The causes for these variations require further exploration.