Synovial Sarcoma in Children, Adolescents, and Young Adults: A Report From the Children's Oncology Group ARST0332 Study

Comparative analysis of bone and soft tissue vs. visceral synovial sarcoma: Demographic, clinical, and survival outcomes; a retrospective population-based study

BACKGROUND

Synovial sarcoma (SS) is typically diagnoses in young adults and usually appears in the extremities and soft tissues. However, it can sometimes arise in visceral organs. This study examines the differences in patient demographics, clinical features, and survival rates between soft tissue and visceral synovial sarcoma.

METHODS

We analyzed data from the Surveillance, Epidemiology, and End Results (SEER) database spanning 2000-2018. ANOVA (analysis of variance) was used to identify significant factors for multivariate analysis. Cox regression modeling was used to determine independent risk factors for survival.

RESULTS

Of the 2,776 SS patients included, the median age was 39.0 years, predominating male (53.0 %) and white (81.3 %). Bone and soft tissue sarcomas were more common, accounting for 86.4 % of cases (p-value<0.001), while the rest were diagnosed as visceral sarcomas. Visceral SS patients were typically older (p-value<0.001), male (56.8 %), and white (84.8 %). They also presented more frequently with distant metastasis (HR 3.8, 95 % CI, 2.4-6.1), had larger tumors on average (HR for tumors >10 cm: 2.9, 95 % CI, 2.0-4.1), and were less likely to undergo surgery (HR 0.4, 95 % CI, 0.3-0.6). Despite receiving multimodal treatments, including surgery, radiation, and/or chemotherapy, visceral SS patients exhibited poorer overall survival compared to their bone and soft tissue SS counterparts (p-value<0.001).

CONCLUSION

Visceral SS often presents in older patients with advanced-stage and larger tumor size as compared to bone and soft tissue SS, which likely contributes to poorer survival. Advanced age, regional spread, and larger tumor size were all found to worsen outcomes, while surgery and radiation were found to be protective factors.

The SS18-SSX fusion oncoprotein: Friend and foe in targeted therapy for synovial sarcoma

Synovial sarcoma is a high-grade soft tissue malignancy characterized by a unique fusion gene known as SS18-SSX. The SS18-SSX fusion protein acts as an oncogenic driver of synovial sarcoma, and it has thus been commonly accepted that disruption of SS18-SSX function represents a therapeutic means of treating synovial sarcoma, but emerging evidence suggests that upon depletion of SS18-SSX, an anti-apoptotic signal surprisingly arises to protect synovial sarcoma cell survival. In this article, we discuss the controversial roles of SS18-SSX's transcriptional activity in synovial sarcoma biology and outline a synergistic strategy for overcoming the resistance of synovial sarcoma cells to SS18-SSX targeted therapeutics.

A comprehensive overview of liquid biopsy applications in pediatric solid tumors

Liquid biopsies are emerging as an alternative source for pediatric cancer biomarkers with potential applications during all stages of patient care, from diagnosis to long-term follow-up. While developments within this field are reported, these mainly focus on dedicated items such as a specific liquid biopsy matrix, analyte, and/or single tumor type. To the best of our knowledge, a comprehensive overview is lacking. Here, we review the current state of liquid biopsy research for the most common non-central nervous system pediatric solid tumors. These include neuroblastoma, renal tumors, germ cell tumors, osteosarcoma, Ewing sarcoma, rhabdomyosarcoma and other soft tissue sarcomas, and liver tumors. Within this selection, we discuss the most important or recent studies involving liquid biopsy-based biomarkers, anticipated clinical applications, and the current challenges for success. Furthermore, we provide an overview of liquid biopsy-based biomarker publication output for each tumor type based on a comprehensive literature search between 1989 and 2023. Per study identified, we list the relevant liquid biopsy-based biomarkers, matrices (e.g., peripheral blood, bone marrow, or cerebrospinal fluid), analytes (e.g., circulating cell-free and tumor DNA, microRNAs, and circulating tumor cells), methods (e.g., digital droplet PCR and next-generation sequencing), the involved pediatric patient cohort, and proposed applications. As such, we identified 344 unique publications. Taken together, while the liquid biopsy field in pediatric oncology is still behind adult oncology, potentially relevant publications have increased over the last decade. Importantly, steps towards clinical implementation are rapidly gaining ground, notably through validation of liquid biopsy-based biomarkers in pediatric clinical trials.

Treatment at relapse for synovial sarcoma of children and adolescents: A multi-institutional European retrospective analysis

PURPOSE

Though the prognosis for pediatric patients with localised synovial sarcoma (SS) is generally good, the chances of being cured after relapse are limited. This study describes a retrospective multi-institutional series of relapsing SS patients treated at six selected European referral centers for pediatric sarcoma.

PATIENTS AND METHODS

The study included 41 patients <21 years with relapsing SS, treated between 2002 and 2022. The analysis included patient's characteristics at first diagnosis, first-line treatments, clinical findings at relapse, and second-line treatment modalities.

RESULTS

The first relapse occurred within 3-132 months (median 18 months) after first diagnosis and was local in 34%, metastatic in 54%, and both in 12%. Treatment at first relapse included surgery in 56% of cases, radiotherapy in 34%, and systemic therapy in 88%. In all, 36 patients received second-line medical treatment, that was chemotherapy in 32 cases (with 10 different regimens) and targeted therapy in four. No patient was included in an early-phase clinical trial as second-line therapy-line therapy. Overall response rate was 42%. Median event-free survival (EFS) was 12 months, postrelapse 5-year EFS was 15.8%. Median overall survival (OS) was 30 months, postrelapse 5-year OS was 22.2%. At the Cox's multivariable regression analysis, OS was significantly associated with time and type of relapse.

CONCLUSION

Pediatric patients with relapsed SS have a poor prognosis and generally receive an individualized approach, due to the lack of a uniform standardized approach. New comprehensive strategies are needed to improve the knowledge on the biologic landscape of SS and develop tailored prospective clinical trials.

Synovial sarcoma: the misdiagnosed sarcoma

Synovial sarcoma is a rare and highly malignant soft tissue sarcoma. The inconspicuous and diversity of its early symptoms make it a highly misdiagnosed disease. The management of synovial sarcomas is challenging as they are rare and have a poor prognosis. Early and correct diagnosis and treatment are critical for clinical outcomes. Misdiagnosis or delayed diagnosis can have devastating consequences for the patient. The detection of SS18 gene rearrangement is considered a powerful tool in establishing the diagnosis of synovial sarcomas. Biopsies and testing for gene rearrangements are recommended for all patients in whom SS cannot be excluded. Surgery is the mainstay of treatment for synovial sarcomas. Neoadjuvant/adjuvant radiotherapy is recommended for patients with big tumors (>5 cm) or positive resection margins, and neoadjuvant/adjuvant chemotherapy is recommended for patients with high-risk tumors or advanced diseases. This article reviews synovial sarcomas from the perspectives of clinical and radiological presentation, histological and cytogenetic analysis, differential diagnosis, treatment, and prognosis.

Outcomes After Preoperative Chemoradiation With or Without Pazopanib in Non-Rhabdomyosarcoma Soft Tissue Sarcoma: A Report From Children's Oncology Group and NRG Oncology

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.ARST1321 was a phase II study designed to compare the near complete pathologic response rate after preoperative chemoradiation with/without pazopanib in children and adults with intermediate-/high-risk chemotherapy-sensitive body wall/extremity non-Rhabdomyosarcoma Soft Tissue Sarcoma (ClinicalTrials.gov identifier: NCT02180867). Enrollment was stopped early following a predetermined interim analysis that found the rate of near complete pathologic response to be significantly greater with the addition of pazopanib. As a planned secondary aim of the study, the outcome data for this cohort were analyzed. Eight-five eligible patients were randomly assigned to receive (regimen A) or not receive (regimen B) pazopanib in combination with ifosfamide and doxorubicin + preoperative radiotherapy followed by primary resection at week 13 and then further chemotherapy at week 25. As of December 31, 2021, at a median survivor follow-up of 3.3 years (range, 0.1-5.8 years), the 3-year event-free survival for all patients in the intent-to-treat analysis was 52.5% (95% CI, 34.8 to 70.2) for regimen A and 50.6% (95% CI, 32 to 69.2) for regimen B (P = .8677, log-rank test); the 3-year overall survival was 75.7% (95% CI, 59.7 to 91.7) for regimen A and 65.4% (95% CI, 48.1 to 82.7) for regimen B (P = .1919, log-rank test). Although the rate of near complete pathologic response was significantly greater with the addition of pazopanib, outcomes were not statistically significantly different between the two regimens.

Synovial Sarcoma in the Extremity: Diversity of Imaging Features for Diagnosis and Prognosis

Synovial sarcomas are rare and highly aggressive soft-tissue sarcomas, primarily affecting adolescents and young adults aged 15-40 years. These tumors typically arise in the deep soft tissues, often near the large joints of the extremities. While the radiological features of these tumors are not definitely indicative, the presence of calcification in a soft-tissue mass (occurring in 30% of cases), adjacent to a joint, strongly suggests the diagnosis. Cross-sectional imaging characteristics play a crucial role in diagnosing synovial sarcomas. They often reveal significant characteristics such as multilobulation and pronounced heterogeneity (forming the "triple sign"), in addition to features like hemorrhage and fluid-fluid levels with septa (resulting in the "bowl of grapes" appearance). Nevertheless, the existence of non-aggressive features, such as gradual growth (with an average time to diagnosis of 2-4 years) and small size (initially measuring < 5 cm) with well-defined margins, can lead to an initial misclassification as a benign lesion. Larger size, older age, and higher tumor grade have been established as adverse predictive indicators for both local disease recurrence and the occurrence of metastasis. Recently, the prognostic importance of CT and MRI characteristics for synovial sarcomas was elucidated. These include factors like the absence of calcification, the presence of cystic components, hemorrhage, the bowl of grape sign, the triple sign, and intercompartmental extension. Wide surgical excision remains the established approach for definitive treatment. Gaining insight into and identifying the diverse range of presentations of synovial sarcomas, which correlate with the prognosis, might be helpful in achieving the optimal patient management.

Synovial sarcoma: characteristics, challenges, and evolving therapeutic strategies

Synovial sarcoma (SS) is a rare and aggressive disease that accounts for 5%-10% of all soft tissue sarcomas. Although it can occur at any age, it typically affects younger adults and children, with a peak incidence in the fourth decade of life. In >95% of cases, the oncogenic driver is a translocation between chromosomes X and 18 that leads to the formation of the SS18::SSX fusion oncogenes. Early and accurate diagnosis is often a challenge; optimal outcomes are achieved by referral to a specialist center for diagnosis and management by a multidisciplinary team as soon as SS is suspected. Surgery with or without radiotherapy and/or chemotherapy can be effective in localized disease, especially in children. However, the prognosis in the advanced stages is poor, with treatment strategies that have relied heavily on traditional cytotoxic chemotherapies. Therefore, there is an unmet need for novel effective management strategies for advanced disease. An improved understanding of disease pathology and its molecular basis has paved the way for novel targeted agents and immunotherapies that are being investigated in clinical trials. This review provides an overview of the epidemiology and characteristics of SS in children and adults, as well as the patient journey from diagnosis to treatment. Current and future management strategies, focusing particularly on the potential of immunotherapies to improve clinical outcomes, are also summarized.

Localized Synovial Sarcoma: A Population-Based Analysis of Treatment Patterns and Survival

Purpose: Synovial sarcoma (SS) is a rare, high-grade soft tissue tumor that requires multidisciplinary and multimodal care with surgery, radiotherapy, and chemotherapy. We examined the impact of sociodemographic and clinical factors on treatment patterns and survival in localized SS patients. Methods: Adolescents and young adults (AYAs, 15-39 years) and older adults ("adults," ≥40 years) diagnosed with localized SS from 2000 to 2018 were identified in the California Cancer Registry. Multivariable logistic regression identified clinical and sociodemographic factors associated with receipt of chemotherapy and/or radiotherapy. Cox proportional hazards regression identified factors associated with overall survival (OS). Results are reported as odds ratios (ORs) and hazard ratios (HRs), respectively, with 95% confidence intervals (CIs). Results: More AYAs (n = 346) than adults (n = 272) received chemotherapy (47.7% vs. 36.4%) and radiotherapy (62.1% vs. 58.1%). Age at diagnosis, tumor size, treatment at National Cancer Institute-Children's Oncology Group (NCI-COG)-designated facilities, insurance status, and neighborhood socioeconomic status (SES) influenced treatment patterns. Among AYAs, treatment at NCI-COG-designated facilities was associated with receiving chemotherapy (OR 2.74, CI 1.48-5.07) and low SES was associated with worse OS (HR 2.28, 1.09-4.77). In adults, high SES was associated with receiving chemoradiotherapy (OR 3.20, CI 1.40-7.31), whereas public insurance was associated with decreased odds of chemoradiotherapy (OR 0.44, CI 0.20-0.95). With regard to treatment, absence of radiotherapy (HR 1.94, CI 1.18-3.20) was associated with worse OS in adults. Conclusion: In localized SS, both clinical and sociodemographic factors influenced treatment patterns. Further research should investigate how SES-related factors produce treatment disparities and identify interventions to improve treatment equity and outcomes.

Relapsed Synovial Sarcoma: Treatment Options

OPINION STATEMENT

Synovial sarcoma (SS) is a fusion-driven subtype of sarcoma that is a more chemo-sensitive subtype of soft tissue sarcoma. While chemotherapy options are currently standard of care, our fundamental understanding of the biology of SS is driving new therapies. We will review the current standard of care, as well as the current therapies showing promise in a clinical trial. It is our hope that by encouraging participation in clinical trials, the fundamental therapies available for SS will change the current treatment paradigm.

Localised Synovial Sarcoma in Adolescents and Young Adults Versus Adults - Is There a Difference in Outcome?

AIMS

Synovial sarcomas are a rare subgroup of soft-tissue sarcoma arising in adolescents and young adults (AYA) and in adult patients. The objective of our analysis was to investigate the outcomes and potential differences of AYA versus adult patients with initially localised disease.

MATERIALS AND METHODS

In total, 51 patients (25 AYA and 26 adult) were identified and evaluated in this retrospective single centre analysis. Baseline characteristics, treatment and outcome were assessed.

RESULTS

The predominant subtype in both groups was monophasic synovial sarcoma (17 AYA and 21 adult) and the most common site was the extremities (14 and 19 patients) with deep tumour location in both groups (33 and 24 patients). More AYA patients had tumours >5 cm (13/25 patients) when compared with adults (10/26 patients, P = n.s.). Primary wide resection was carried out in 15 AYAs and in 18 adults. Postoperative radiation therapy was the only statistical difference between AYA (n = 19) and adult patients (n = 12; P = 0.029). Nineteen and 17 patients, respectively, received adjuvant chemotherapy with no evidence of disease after six cycles. Nine and 11 patients relapsed after initial therapy and the most common metastatic site was the lung (eight versus nine patients). Five-year overall survival rates were 85% and 75%. Female gender, tumour size ≤5 cm and absence of progressive disease showed a significant association with overall survival in AYA patients (P = 0.013, P = 0.04 and P < 0.001), whereas non-extremity tumours and progression after initial therapy were significant for worse overall survival in adult patients (P = 0.012 and P < 0.001). No difference in overall survival between AYA and adult patients was observed (P = 0.899).

CONCLUSIONS

AYA and adult patients showed no significant difference in terms of overall survival. Male gender, tumour size >5 cm and progressive disease were prognostic markers for worse outcome, whereas tumour location (non-extremity) and progression after initial therapy were markers for worse outcome in adult patients.

Current clinical perspective of urological oncology in the adolescent and young adult generation

Among adolescents and young adults, hematological tumors are the most common malignancies in younger patients; however, solid tumors also increase with advancing age. The pathogenesis of some of these tumors differs from that of tumors which develop in children, or middle-aged and older adults, and special care should be taken in their treatment and management. A treatment plan that takes into consideration future fertility is necessary for testicular tumors, and an educational campaign to encourage early detection is also essential. The treatment of adolescents with advanced testicular tumors should resemble therapeutic approaches for young adults and not a pediatric regimen. Adrenal tumors often develop as part of familiar hereditary syndrome. Therefore, taking the personal and family history is very important, and genetic counseling should be also recommended. In renal tumors, the incidence of translocation renal cell carcinomas is higher. Complete resection is the only promising method for long-term prognosis because of no established treatment for translocation renal cell carcinomas with distant metastasis. Bladder tumors are often detected by symptoms of gross hematuria and are found at a relatively early stage. Along with renal tumors, oncological evaluation including cystoscopy is also considered essential for gross hematuria. Wilms tumors and rhabdomyosarcomas could be managed in accordance with pediatric protocols to improve the treatment outcomes. The dedicated cancer survivorship care for adolescents and young adults could be also indispensable to conquer cancer and maintain a better quality of life.

Soft-tissue sarcoma in adolescents and young adults

Soft-tissue sarcoma is a rare cancer that accounts for approximately 1% of all malignant tumors. Although they occur in various age groups, soft-tissue sarcomas account for 8% of all malignant tumors developing in adolescents and young adults, suggesting that they are not rare in this age group. This study aimed to evaluate the clinical and pathological characteristics of soft-tissue sarcoma in adolescents and young adults. According to the Bone and Soft-Tissue Tumor Registry in Japan, myxoid liposarcoma is the most common type of soft-tissue sarcoma found in adolescents and young adults; alveolar soft part sarcoma, extraskeletal Ewing sarcoma, epithelioid sarcoma, clear cell sarcoma and synovial sarcoma occur predominantly in this age group among soft-tissue sarcomas. The analysis based on this registry demonstrated that age was not a prognostic factor for poor survival of soft-tissue sarcoma, although the prognosis in adolescents and young adults was better than that in older patients in the US and Scandinavia. Adolescent and young adult patients with soft-tissue sarcoma have age-specific problems, and a multidisciplinary approach to physical, psychological, and social issues is necessary to improve the management of these young patients both during and after treatment.

Derivation and validation of a risk classification tree for patients with synovial sarcoma

BACKGROUND

Synovial sarcoma (SS) accounts for 8%-10% of all soft-tissue sarcomas. Clinical presentation and outcomes vary, yet discrete risk groups based on validated prognostic indices are not defined for the full spectrum of patients with SS.

METHODS

We performed a retrospective cohort study using data from the SEER (surveillance, epidemiology, and end results program) database of SS patients who were <70 years of age at diagnosis. We constructed a recursive partitioning model of overall survival using a training cohort of 1063 patients with variables: Age at diagnosis, sex, race, ethnicity, primary site, tumor size, tumor grade, and stage. Based on this model, we grouped patients into three risk groups and estimated 5-year overall survival for each group. We then applied these groups to a test cohort (n = 1063).

RESULTS

Our model identified three prognostic groups with significantly different overall survival: low risk (local/regional stage with either <21 years of age OR tumor <7.5 cm and female sex), intermediate-risk (local/regional stage, age ≥ 21 years with either male sex and tumor <7.5 cm OR any sex with appendicular anatomic location) and high risk (local/regional stage, age ≥ 21 years, tumor size ≥7.5 cm and non-appendicular location OR distant stage). Prognostic groups were applied to the test cohort, showing significantly different survival between groups (p < 0.0001).

CONCLUSIONS

Our analysis yields an intuitive risk-classification tree with discrete groups, which may provide useful information for researchers, patients, and clinicians. Prospective validation of this model may inform efforts at risk-stratifying treatment.

Pediatric Non-Rhabdomyosarcoma Soft Tissue Sarcomas: Standard of Care and Treatment Recommendations from the European Paediatric Soft Tissue Sarcoma Study Group (EpSSG)

This paper describes the standard of care for patients with non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) and the therapeutic recommendations developed by the European paediatric Soft tissue sarcoma Study Group (EpSSG). NRSTS form a very mixed group of mesenchymal extraskeletal malignancies. Their rarity, heterogeneity, and aggressiveness make the management of children and adolescents with these tumors complex and challenging. The overall cure rate for patients with NRSTS is around 70%, but survival depends on several prognostic variables, such as histotype and tumor grade, extent of disease and stage, tumor size, and tumor site. While surgery remains the mainstay of treatment for most of these tumors, a multimodal therapeutic approach including radiotherapy and chemotherapy is required in many cases. The EpSSG NRSTS 2005 study was the first prospective protocol tailored specifically to NRSTS. Together with the ARST0332 study developed by the North-American Soft Tissue Sarcoma Committee of the Children's Oncology Group (COG), the EpSSG NRSTS 2005 study currently represents the benchmark for these tumors, establishing risk-adapted standards of care. The EpSSG has developed common treatment recommendations for the large group of adult-type NRSTS (including synovial sarcoma), and specific treatment recommendations for other particular adult-type histologies (ie, alveolar soft-part sarcoma, clear cell sarcoma and dermatofibrosarcoma protuberans); other highly malignant tumors with a biology and clinical behavior differing from those of adult-type NRSTS (ie, rhabdoid tumors and desmoplastic small round cell tumor); and soft tissue tumors of intermediate malignancy (ie desmoid-type fibromatosis, inflammatory myofibroblastic tumors, and infantile fibrosarcoma). New effective drugs are needed for patients whose NRSTS carries the worst prognosis, ie, those with unresectable tumors, metastases at diagnosis, or relapsing disease. Progress in this area relies on our ability to develop international integrated prospective collaborations, both within existing pediatric oncology networks and, importantly, between the communities of specialists treating pediatric and adult sarcoma.

Management of Synovial Sarcoma and Myxoid Liposarcoma

Synovial sarcoma and myxoid liposarcoma are translocation-related sarcomas, with a high risk of developing distant metastasis, which often affect young patients and which are sensitive to chemo and radiotherapy. Surgery is the mainstay of therapy in localized disease. In these entities, perioperative radiotherapy is frequently administered, and chemotherapy is evaluated in patients with high-risk limb/trunk wall tumors in which an advantage in overall survival has been shown in the latest clinical trials. In the advanced setting, new strategies, such as cellular therapy are being developed in these histologic types, with promising, although still preliminary, results.

Pre-operative radiotherapy is associated with superior local relapse-free survival in advanced synovial sarcoma

PURPOSE

Optimization of local therapies in synovial sarcoma (SS) considered unresectable at diagnosis is needed. We evaluated the effects of neoadjuvant versus adjuvant radiation versus surgery only on long-term outcomes.

METHODS

Patients with macroscopic SS tumors before chemotherapy (IRS-group-III) in the trials CWS-81, CWS-86, CWS-91, CWS-96, CWS-2002-P and SoTiSaR-registry were analyzed. Local therapies were scheduled after 3 neoadjuvant chemotherapy cycles.

RESULTS

Median age of 145 patients was 14.5 years. 106 survivors had median follow-up of 7.0 years. Tumor site was 96 extremities, 19 head-neck, 16 shoulder/hip, 14 trunk. Tumors were < 3 cm in 16, 3-5 cm in 28, 5-10 cm in 55, > 10 cm in 34 patients. In a secondary resection during chemotherapy, R0-status was accomplished in 82, R1 in 30, R2 in 21 (12 missing). Radiotherapy was administered to 115 (R0 61, R1 29, R2 20, missing 5), thereof 57 before and 52 after tumor resection. 23 were treated with surgery only. For all patients, 5 year event-free (EFS) and overall survival (OS) was 68.9% ± 7.6 (95%CI) and 79.1% ± 6.9. To establish independent significance, tumor site, size, surgical results and sequencing of local therapies were analyzed in a Cox regression analysis. Variables associated with EFS and OS are site, size and sequencing of local therapies. Variables associated with local recurrence are site, surgical results and sequencing of local therapies. The only variable associated with suffering metastatic recurrence is tumor size.

CONCLUSION

Differences in sequencing of local therapy procedures are independently associated with outcomes. Best local control is achieved when tumors are irradiated pre-operatively and undergo R0 or R1 resection thereafter.

Genotyping of Circulating Free DNA Enables Monitoring of Tumor Dynamics in Synovial Sarcomas

Simple Summary

Synovial sarcomas (SS) are rare soft tissue tumors of mesenchymal origin. Following resection of the primary tumor, about one third to half of the patients suffer from recurrence. Detection of local and distant recurrence during follow-up is commonly accomplished by imaging. There are no biomarkers available for routine diagnostics. We employ a highly sensitive targeted next-generation sequencing approach to monitor tumor dynamics by genotyping of circulating free DNA (cfDNA) in SS patients. cfDNA which harbors tumor-specific mutations (circulating tumor-DNA; ctDNA) correlated with the presence of viable tumor tissue. This enables timely and non-invasive detection of tumor recurrence and monitoring of treatment response independent of the anatomic location.

Abstract

Background: Synovial sarcoma (SS) is a malignant soft tissue tumor of mesenchymal origin that frequently occurs in young adults. Translocation of the SYT gene on chromosome 18 to the SSX genes on chromosome X leads to the formation of oncogenic fusion genes, which lead to initiation and proliferation of tumor cells. The detection and quantification of circulating tumor DNA (ctDNA) can serve as a non-invasive method for diagnostics of local or distant tumor recurrence, which could improve survival rates due to early detection. Methods: We developed a subtype-specific targeted next-generation sequencing (NGS) approach specifically targeting SS t(X;18)(p11;q11), which fuses SS18 (SYT) in chromosome 18 to SSX1 or SSX2 in chromosome x, and recurrent point mutations. In addition, patient-specific panels were designed from tumor exome sequencing. Both approaches were used to quantify ctDNA in patients’ plasma. Results: The subtype-specific assay allowed detection of somatic mutations from 25/25 tumors with a mean of 1.68 targetable mutations. The minimal limit of detection was determined at a variant allele frequency of 0.05%. Analysis of 29 plasma samples from 15 tumor patients identified breakpoint ctDNA in 6 patients (sensitivity: 40%, specificity 100%). The addition of more mutations further increased assay sensitivity. Quantification of ctDNA in plasma samples (n = 11) from one patient collected over 3 years, with a patient-specific panel based on tumor exome sequencing, correlated with the clinical course, response to treatment and tumor volume. Conclusions: Targeted NGS allows for highly sensitive tumor profiling and non-invasive detection of ctDNA in SS patients, enabling non-invasive monitoring of tumor dynamics.

International Society of Paediatric Surgical Oncology (IPSO) Surgical Practice Guidelines

Most children with tumors will require one or more surgical interventions as part of the care and treatment, including making a diagnosis, obtaining adequate venous access, performing a surgical resection for solid tumors (with staging and reconstruction), performing procedures for cancer prevention and its late effects, and managing complications of treatment; all with the goal of improving survival and quality of life. It is important for surgeons to adhere to sound pediatric surgical oncology principles, as they are closely associated with improved local control and survival. Unfortunately, there is a significant disparity in survival rates in low and middle income countries, when compared to those from high income countries. The International Society of Paediatric Surgical Oncology (IPSO) is the leading organization that deals with pediatric surgical oncology worldwide. This organization allows experts in the field from around the globe to gather and address the surgical needs of children with cancer. IPSO has been invited to contribute surgical guidance as part of the World Health Organization Initiative for Childhood Cancer. One of our goals is to provide surgical guidance for different scenarios, including those experienced in High- (HICs) and Low- and Middle-Income Countries (LMICs). With this in mind, the following guidelines have been developed by authors from both HICs and LMICs. These have been further validated by experts with the aim of providing evidence-based information for surgeons who care for children with cancer. We hope that this initiative will benefit children worldwide in the best way possible. Simone Abib, IPSO President Justin T Gerstle, IPSO Education Committee Chair Chan Hon Chui, IPSO Secretary.

Synovial sarcoma of the head and neck: A review of reported cases on the clinical characteristics and treatment methods

Synovial sarcoma (SS) is a high-grade soft-tissue sarcoma that occurs predominantly in older children and young adults in their thirties. It is usually very challenging to diagnose and treat synovial sarcoma in the head and neck region. The purpose of this review is to investigate the clinical manifestations and different treatment methods in the management of primary synovial sarcoma of the head and neck. HNSS has an aggressive nature and poor prognosis. Surgical resection, radiotherapy, and chemotherapy are the primary treatment methods. Typically, surgical resection with negative margins remains the foundation of therapy, which is not very easily achieved in the head and neck due to its complex anatomical structure and the presence of many blood vessels and nerves. However, synovial sarcoma has a high recurrence rate, so aggressive management and close follow-up are warranted for the optimal outcome.