Background To assess the outcomes of pediatric patients with Undifferentiated Embryonal Sarcoma of the Liver (UESL) and treatment including at least surgery and systemic chemotherapy. Methods This study included patients aged up to 21 years with a pathological diagnosis of UESL prospectively enrolled from 1995 to 2016 in three european trials focusing on the effects of surgical margins, preoperative chemotherapy, use of radiotherapy (RT) and chemotherapy. Results Out of 65 patients with a median age at diagnosis of 8.7 years (0.6-20.8), 15 had T2 tumors, and 1 had lymph node spread, 14 were Intergroup Rhabdomyosarcoma Study (IRS) I, 9 IRSII, 38 IRSIII, and 4 IRSIV. Twenty-eight upfront surgeries resulted in 5 operative spillages and 11 infiltrated surgical margins, whereas 37 delayed surgeries resulted in no spillages (P= 0.0119) and 3 infiltrated margins (P=0.0238). All patients received chemotherapy, including anthracyclines in 47. Radiotherapy was administered in 15 patients. With a median follow-up of 78.6 months, 5 year overall and event free survivals (EFS) were 90.1% (95%CI 79.2-95.5) and 89.1% (95%CI 78.4-94.6), respectively. Two out 4 local relapses had previous infiltrated margins and 2 out of 3 patients with metastatic relapses received reduced doses of alkylating agents. Infiltrated margins (P=0.1607), T2 stage (P=0.3870), use of RT (P= 0.8731), and anthracycline-based chemotherapy (P= 0.1181) were not correlated with EFS. Conclusions Neoadjuvant chemotherapy for pediatric patients with UESL increases the probability of complete surgical resection. The role of anthracyclines and radiotherapy for localized disease remains unclear. The use of alkylating agents is recommended.

BACKGROUND: Rhabdomyosarcoma (RMS) is an aggressive malignancy, and 20% of children present with metastases at diagnosis. Patients presenting with disseminated disease very occasionally have no clear evidence of a primary tumor mass. Since these patients have rarely been investigated, we report on a series of patients with RMS and unknown primary tumor site registered in the MTS 2008 protocol (October 2008 - December 2016) coordinated by the European pediatric Soft tissue sarcoma Study Group. METHODS: Patients were administered 9 cycles of induction chemotherapy, and 48 weeks of maintenance chemotherapy. Surgery and/or radiotherapy was planned after the first assessment of tumor response, and implemented after six cycles of chemotherapy. If feasible, radiotherapy to all sites of metastasis was recommended. RESULTS: We identified 10 patients with RMS and unknown primary site, most of them adolescents (median age 15.8 years, range 4.6-20.4). Nine had fusion-positive alveolar RMS. Multiple organ involvement was identified in 7 patients, 2 only had bone marrow disease, and 1 only had leptomeningeal dissemination. All patients were given chemotherapy, 4 were irradiated, and none had surgery. Three patients underwent allogeneic bone marrow transplantation. At the time of this analysis, only 2 patients are alive in complete remission: 1 had received radiotherapy; and 1 had a bone marrow transplant. CONCLUSIONS: RMS with unknown primary tumor occurs mainly in adolescents and is typically fusion-positive alveolar. Radiotherapy may be important, but survival is poor and patients should be offered enrollment in investigational trials.

Background: Postoperative hypocalcemia is a frequent complication after thyroid surgery. Hypoparathyroidism may develop as transient (TtHP), with normalization within six months from surgery, or permanent (PtHP) if the patient requires replacement therapy. The present study analyzes rates and factors associated with the development of TtHP or PtHP following thyroid surgery in a pediatric population. Procedure: A retrospective multicenter study analyzing 363 patients was carried out. We recorded gender, age, tumor size, type of surgery, lymph node dissection, histology. Calcium levels were acquired daily for 72 hours after discharge. Subsequent sample collection was customized on the patient’s hypocalcemia severity. Results: We analyzed 363 patients aged ≤18 years (mean age 14.2 years) who underwent thyroid surgery clustered into age groups (≤15 or >15). Patients mean follow-up was 5.8 years (1-11yrs). At histology 310 (85%) were papillary carcinoma, 32 (9%) were follicular carcinoma, 6 (2%) presented diffuse sclerosing variant of papillary thyroid carcinoma whilst 15 (4%) had familial medullary carcinoma. TtHP developed in 36 (9,9%), PtHP in 20 (5.5%) cases. TtHP was more frequent in younger patients (p=0,009). Both PtHP and TtHP were increased in case of larger tumors (≥2 cm) (p=0,001). All TtHP and PtHP were in TT group. PtHP rate was increased if lymph node dissection was carried out (p<0.001). Conclusions: The risk of hypoparathyroidism is related to younger age, tumor size, TT and lymph node dissection therefore surgeons should tailor surgery as much as possible to avert such complication.

Pancreatoblastoma (PBL) is a rare malignant epithelial neoplasm affecting typically young children. Signs related to advanced upper-abdominal tumor accompanied by elevated serum α-fetoprotein levels in a young child suggest PBL, however histopathological examination is required for diagnosis. The mainstay of treatment is a complete surgical resection. Inoperable and/or metastatic PBL may become amenable to complete, delayed surgery after neo-adjuvant chemotherapy. This manuscript presents the internationally consensus recommendations for the diagnosis and treatment of children with PBL, established by the European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT) within the EU-funded PARTNER (Paediatric Rare Tumors Network – European Registry) project.

As part of the European Union-funded project designated PARTN-ER, the European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT) is continuously developing consensus recommendations in order to harmonize standard care for very rare solid tumors of children and adolescents. This paper presents the internationally recognized recommendations for the diagnosis and treatment of sex cord stromal tumors (SCST). The clinical approach to sex cord stromal tumors of the testis (TSCST) and ovary (OSCST) depends on histological differentiation and tumor stage. Virtually all TSCSTs present as localized non-metastatic tumors, with excellent prognosis after complete resection. In contrast, the prognosis of OSCSTs may be adversely affected by tumor spillage during surgery or presence of metastases. In these cases, cisplatin-based chemotherapy is recommended. Of note, some SCSTs may develop in the context of tumor predisposition syndromes e.g. DICER-1, so that specific follow-up is indicated. SCSTs should be diagnosed and treated according to standardized recommendations that include reference pathology, genetic testing for tumor predisposition syndromes in selected cases, and stratified adjuvant chemotherapy in patients with unfavorable risk profile. To ensure high quality of diagnosis and therapy, patients should be enrolled into prospective registries.

BACKGROUND: Irinotecan is a drug active against pediatric sarcomas with a toxicity profile that theoretically allows for its association with more myelotoxic drugs. We examined the feasibility of a dose-density strategy integrating irinotecan in standard chemotherapy regimens for patients with high-risk sarcomas. METHODS: Between November 2013 and January 2020, 23 patients < 21 years old with metastatic (11 children) or recurrent (12 children) sarcomas were treated with 9 IrIVA/IrVAC cycles. All newly-diagnosed patients received IrIVA (ifosfamide 3g/m2 on days 1 and 2, vincristine 1.5 mg/m2 on day 1, actinomycin D 1.5 mg/m2 on day 1, irinotecan 20 mg/m2 for 5 consecutive days starting on day 8). Two relapsed patients received IrIVA and 10 IrVAC (cyclophosphamide 1.5 g/m2 on day 1 instead of ifosfamide). Feasibility was assessed in terms of toxicity and time to complete the treatment. RESULTS: 17 rhabdomyosarcomas, 4 Ewing sarcomas, 2 desmoplastic round cell tumors received a total of 181 cycles (range 2-10). Grade 4 neutropenia occurred in 62.4% of the cycles. 13 patients had febrile neutropenia. Diarrhea occurred in 14 cycles. The median time to complete the treatment was 195 days (range 170-231), 83.4% of cycles were administered on time or with a delay <1 week. With a median follow-up of 2.6 years (range 0.2-5.0), 12 patients are alive, 9 complete remissions, 3 with the disease. Conclusions: A dose density strategy combining irinotecan with standard chemotherapy is feasible. This approach will be investigated in the next trial coordinated by the European pediatric Soft tissue sarcoma Study Group.

Background: Treatment of children and adolescents with alveolar rhabdomyosarcoma (ARMS) and regional nodal involvement (N1) have been approached differently by North American and European cooperative groups. In order to define the better therapeutic strategy, we analyzed two studies conducted between 2005 and 2016 by the European paediatric Soft tissue sarcoma Study Group (EpSSG) and Children’s Oncology Group (COG). Methods: We retrospectively identified patients with ARMS N1 enrolled in either EpSSG RMS2005 or in COG ARST0531. Chemotherapy in RMS2005 comprised IVADo (ifosfamide, vincristine, dactinomycin, doxorubicin), IVA and maintenance (vinorelbine, cyclophosphamide); in ARST0531 it consisted on either VAC (vincristine, dactinomycin, cyclophosphamide) or VAC alternating with VI (vincristine, irinotecan). Local treatment was similar in both protocols. Results: The analysis of the clinical characteristics of 239 patients showed some differences between study groups: in RMS2005, advanced IRS Group and large tumors predominated. There were no differences in outcomes between the two groups: 5-year event-free survival (EFS), 49% (95%CI=39-59) and 44% (95%CI=30-58), and overall survival (OS), 51% (95%CI=41-61) and 53.6% (95%CI=40-68), in RMS2005 and ARST0531, respectively. In RMS2005, EFS of patients with FOXO1-positive tumors was significantly inferior to those FOXO1-negative (49.3% vs 73%, p=0.034). In contrast, in ARST0531, EFS of patients with FOXO1-positive tumors was 45% compared with 43.8% for those FOXO1-negative. Conclusions: The outcome of patients with ARMS N1 was similar using different schemas of chemotherapy. However, patients with FOXO1 fusion-negative tumors enrolled in RMS2005 showed a significantly better outcome, suggesting that this subgroup may benefit from the EpSSG strategy which included maintenance chemotherapy.

Pediatric oncology is justifiably proud of its long tradition of multi-institutional collaboration in clinical research. Perhaps no other field of medicine has more effectively shown what can be achieved by pooling talent and resources to study challenging diseases. Historically, most collaborative projects were limited to a single country or continent. However, more progress comes from even broader international cooperation. With rare cancers, this may be the only way to gather sufficient patient numbers to address key questions. Sharing national experiences can also lead to a deeper understanding of the advantages and risks associated with different therapeutic approaches. The first steps to increased global cooperation, however, is agreeing on a common language to describe patient cohorts and consensus standards to guide diagnosis, evaluation, and treatment. Applying these lofting goals to pediatric soft tissue sarcomas, the INternational Soft Tissue SaRcoma ConsorTium (INSTRuCT) was born.From its initial formative meeting in May 2017, INSTRuCT has patterned its structure and purpose on the successful model of the International Neuroblastoma Risk Group (INRG).1,2 The membership of INSTRuCT is composed of three large cooperative clinical trials organizations: Children’s Oncology Group (COG), Cooperative Weichteilsarkom Studiengruppe (CWS), and European paediatric Soft tissue sarcoma Study Group (EpSSG). The first goal for INSTRuCT is to develop an international risk stratification system for rhabdomyosarcoma (RMS) to replace competing systems used in Europe and North America. A common RMS risk stratification system would facilitate the comparison of clinical trial results across cooperative groups. Before generating a RMS risk stratification system, INSTRuCT agreed upon a standard RMS data dictionary, leveraging the University of Chicago’s Pediatric Cancer Data Commons expertise in data standardization.3 The compilation of COG, CWS, and EpSSG data (and data from their legacy groups) from finished studies into a single INSTRuCT dataset is nearly complete, and will include more than 7000 patients enrolled on previous RMS clinical trials. Once the RMS risk stratification project is finished, INSTRuCT will mine its dataset for answers to questions that can only be addressed with large, well-annotated clinical data. Future work will also include expanding the RMS data dictionary and adding a non-RMS soft tissue sarcoma dataset, also drawn from COG, CWS, and EpSSG clinical trials.As the multi-disciplinary members of INSTRuCT were defining their RMS data dictionary, they realized they had the opportunity to develop international consensus statements on the diagnosis, evaluation, and management of pediatric soft tissue sarcomas. Clinical trial protocols include guidelines for pathologic diagnosis, imaging staging evaluation, and local control approaches with surgery and radiation therapy varied by primary anatomic site. INSTRuCT provided the forum for international discussion and consensus building, with the goal of publishing these expert opinions for broad dissemination and use by pediatric oncologists, surgeons, radiation oncologists, radiologists, and pathologists worldwide. In this issue of Pediatric Blood & Cancer, Morris et al. publish the one of first in a series of consensus statements from INSTRuCT, focusing on the surgical management in the diagnosis and local control of RMS arising in the extremity.4 Morris et al. outline recommended biopsy approaches, the rational for routine use of regional lymph node evaluation including the role of fluorodeoxyglucose positron emission tomography, and the decision-making behind up-front versus delayed primary excision. The recommendations are guided by the principles of maximizing oncologic outcome while maintaining extremity function. Given the rarity of extremity RMS and the absence of randomized trials comparing different management strategies, Morris et al. draw upon a combination of clinical data and expert opinion in their consensus guidelines, carefully documenting the level of evidence that supports each of their recommendations. Nonetheless, these guidelines represent the current state of the art for surgical management of extremity RMS and the basis for future clinical trial recommendations. A similar consensus statement on RMS of the female genital tract has also been published in Pediatric Blood & Cancer, by Lautz et al.5 With these two consensus statements, the INSTRuCTPediatric Blood & Cancer special series is off to an excellent start, with manuscripts on the surgical management for other primary sites and the pathologic evaluation of RMS to follow soon. As INSTRuCT co-chairs, we are pleased to introduce INSTRuCT to the global pediatric oncology community and look forward to many more contributions to come.

Background The International Soft Tissue Sarcoma Consortium (INSTRuCT) was founded as an international collaboration between different pediatric soft tissue sarcoma cooperative groups (COG, EpSSG, CWS). Besides other tasks, a major goal of the INSTRuCT is to develop consensus expert opinions for best clinical treatment. This consensus paper for patients with rhabdomyosarcoma of the female genital tract (FGU-RMS) provides treatment recommendations for local treatment, long term follow up and fertility preservation. Methods Review of the current literature was combined with recommendations of the treatment protocols of the appropriate clinical trials. Additionally, opinions of international FGU-RMS experts were incorporated into recommendations. Results The prognosis of FGU-RMS is favorable with an excellent response to chemotherapy. Initial complete surgical resection is not indicated, but diagnosis should be established properly. In patients with tumors localized at the vagina or cervix demonstrating incomplete response after induction chemotherapy, local radiotherapy (brachytherapy) should be carried out. In patients with persistent tumors at the corpus uteri, hysterectomy should be performed. Fertility preservation should be considered in all patients. Conclusion For the first time, an international consensus for the treatment of FGU-RMS patients could be achieved, which will help to harmonize the treatment in different study groups.