Embryonal and alveolar rhabdomyosarcoma in adolescents/young adults, adults and older adults: a population-based cohort study.

BACKGROUND: The clinical characteristics, outcomes, and prognostic factors of adult embryonal rhabdomyosarcomas (ERMS) and alveolar rhabdomyosarcomas (ARMS), particularly the differences among adolescents/young adults (AYA), adults, and older adults, remain unclear. We assessed the clinicopathological features and survival outcomes of adult patients with ERMS and ARMS in Japan and to compare these features among AYA, adult, and older adult patients. METHODS: We retrospectively analyzed data from the Bone and Soft Tissue Tumor Registry of Japan and enrolled patients aged ≥15 years with ERMS and ARMS. Disease-specific overall survival (DOS) was estimated using the Kaplan-Meier method, and a Cox regression model was used to identify prognostic factors. RESULTS: Among 184 patients with ERMS and ARMS (median age, 27 years; interquartile range, 18-49 years), a high rate of distant and regional nodal metastases was initially observed in 65 (35%) and 66 (36%) cases, respectively. Older age and distant metastasis at first presentation were statistically poor prognostic factors, and histological subtype and site of tumor origin were not associated with DOS. In patients with localized ERMS and ARMS, older age and nodal metastasis were poor prognostic factors; the 5-year DOS rates of patients with and without nodal metastasis were 23% and 72%, respectively. CONCLUSIONS: Older patients with rhabdomyosarcoma had a dismal prognosis, and distant metastasis was a poor prognostic factor. The prognostic factors differed between adult and pediatric patients with rhabdomyosarcoma; biological analyses, such as genome analysis of adult rhabdomyosarcoma and clinical trials with pediatric oncologists, are needed to improve the prognosis of adult rhabdomyosarcoma.

Prognostic Factors in Pediatric Alveolar Rhabdomyosarcoma: SEER Analysis of 277 Cases.

Alveolar rhabdomyosarcoma (ARMS) is a rare but highly aggressive cancer predominantly affecting children and adolescents. This study explores prognostic factors for pediatric and adolescent ARMS, using the Surveillance, Epidemiology, and End Results (SEER) database. Leveraging SEER data (2000-2019), we analyzed 277 cases. Employing Kaplan-Meier survival analysis and Cox proportional hazards models, we identified significant prognostic factors. Gender distribution was nearly equal (56.0% boys, 44.0% girls), with the majority (70.8%) from the white ethnic group. Primary tumors were predominantly in extremities (37.2%). Distant metastases significantly increased mortality risk (hazard ratio [HR], 3.13; 95% CI: 2.14-4.58) and regional lymph node involvement raised mortality risk (HR, 1.36; 95% CI: 0.96-1.92). Chemotherapy-only treatment had higher mortality risk than chemoradiotherapy (HR, 1.16; 95% CI: 0.97-2.67). Conclusively, our study identifies distant metastases, regional lymph node involvement, and treatment modality as crucial predictors of overall survival in pediatric ARMS.

Genomic Classification and Clinical Outcome in Rhabdomyosarcoma: A Report From an International Consortium.

PURPOSE: Rhabdomyosarcoma is the most common soft tissue sarcoma of childhood. Despite aggressive therapy, the 5-year survival rate for patients with metastatic or recurrent disease remains poor, and beyond PAX-FOXO1 fusion status, no genomic markers are available for risk stratification. We present an international consortium study designed to determine the incidence of driver mutations and their association with clinical outcome. PATIENTS AND METHODS: Tumor samples collected from patients enrolled on Children's Oncology Group trials (1998-2017) and UK patients enrolled on malignant mesenchymal tumor and RMS2005 (1995-2016) trials were subjected to custom-capture sequencing. Mutations, indels, gene deletions, and amplifications were identified, and survival analysis was performed. RESULTS: DNA from 641 patients was suitable for analyses. A median of one mutation was found per tumor. In FOXO1 fusion-negative cases, mutation of any RAS pathway member was found in > 50% of cases, and 21% had no putative driver mutation identified. BCOR (15%), NF1 (15%), and TP53 (13%) mutations were found at a higher incidence than previously reported and TP53 mutations were associated with worse outcomes in both fusion-negative and FOXO1 fusion-positive cases. Interestingly, mutations in RAS isoforms predominated in infants < 1 year (64% of cases). Mutation of MYOD1 was associated with histologic patterns beyond those previously described, older age, head and neck primary site, and a dismal survival. Finally, we provide a searchable companion database (ClinOmics), containing all genomic variants, and clinical annotation including survival data. CONCLUSION: This is the largest genomic characterization of clinically annotated rhabdomyosarcoma tumors to date and provides prognostic genetic features that refine risk stratification and will be incorporated into prospective trials.

Disease Control and Patterns of Failure After Proton Beam Therapy for Rhabdomyosarcoma.

PURPOSE: Pediatric patients with rhabdomyosarcoma (RMS) are treated with multimodal therapy, often with radiation therapy (RT) as part of local therapy. We report on the efficacy and patterns of failure after proton beam therapy (PBT) for RMS. METHODS AND MATERIALS: Between January 2006 and February 2017, patients with RMS were enrolled in a prospective institutional review board-approved registry protocol for pediatric patients undergoing PBT. Demographics, clinical characteristics, and treatment related outcomes were reviewed. RESULTS: Ninety-four RMS patients were treated with a combination of chemotherapy (CT) and PBT. The majority of patients had head and neck (49%) and genitourinary (30%) primaries. Median tumor size was 4.1 cm (range, 1.0-16.5 cm); 33 patients (35%) had primary tumors >5 cm. Median cyclophosphamide equivalent dose was 14.4 g/m2 (range, 0-30.8 g/m2). Median time from CT initiation to RT initiation was 13 weeks (range, 1-58 weeks). With median follow-up of 4 years, 4-year overall survival (OS) was 71%, and 4-year progression-free survival (PFS) was 63%. Thirty patients (32%) experienced relapse (13% with local failure [LF]). Four-year local control (LC) was 85% overall; 4-year LC rates were 100% for low-risk, 85% for intermediate-risk, and 55% for high-risk patients (P = .02). Tumor size predicted LC (P = .007), with 7% versus 33% LF rate by tumor size (≤5 cm vs >5 cm). Delayed RT delivery (≥13 weeks from initiation of CT) predicted worse LC (P = .01). Increased tumor size predicted both inferior PFS (P = .02) and OS (P = .01). Delayed RT delivery predicted both inferior PFS (P = .04) and OS (P = .03). CONCLUSIONS: PBT provides LC comparable to prior studies using photon RT. Inferior LC, PFS, and OS rates were observed for patients with larger tumors and those treated with delayed RT. This finding supports ongoing prospective efforts to dose-escalate treatment of tumors >5 cm; however, these data call into question the optimal timing of local therapy, particularly for patients treated with reduced-dose cyclophosphamide.

Alveolar rhabdomyosarcoma with regional nodal involvement: Results of a combined analysis from two cooperative groups.

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 a 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 ifosfamide + vincristine + dactinomycin + doxorubicin (IVADo), IVA and maintenance (vinorelbine, cyclophosphamide); in ARST0531, it consisted of either vincristine + dactinomycin + cyclophosphamide (VAC) or VAC alternating with vincristine + irinotecan (VI). 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 Intergroup Rhabdomyosarcoma Study Group (IRS) and large tumors predominated. There were no differences in outcomes between the two groups: 5-year event-free survival (EFS), 49% (95% confidence interval [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 with FOXO1-negative (49.3% vs 73%, P = .034). In contrast, in ARST0531, EFS of patients with FOXO1-positive tumors was 45% compared with 43.8% for those with FOXO1-negative. CONCLUSIONS: The outcome of patients with ARMS N1 was similar in both protocols. However, patients with FOXO1 fusion-negative tumors enrolled in RMS2005 showed a significantly better outcome, suggesting that different strategies of chemotherapy may have an impact in the outcome of this subgroup of patients.

Do children and adolescents with completely resected alveolar rhabdomyosarcoma require adjuvant radiation? A report from the Children's Oncology Group.

BACKGROUND: The role of adjuvant radiotherapy (RT) remains unclear in patients with localized, completely resected (group I) alveolar rhabdomyosarcoma (ARMS). PROCEDURE: Patients with group I ARMS enrolled on any one of three prior Children's Oncology Group (COG) clinical trials (D9602, D9803, or ARST0531) were analyzed. All patients received systemic chemotherapy and 36 Gy adjuvant RT (if given) to the primary site at week 12 or week 4 for D9602/D9803 and ARST0531, respectively. RESULTS: Thirty-six patients with group I ARMS were treated on D9602 (n = 6), D9803 (n = 17), or ARST0531 (n = 13), of whom 24 (67%) were male. The median age was 4.1 years (range, 0.8-45.8). Twenty (56%) patients had an unfavorable primary site, and 10 (28%) had tumors > 5 cm. FOXO1-fusion status was negative, positive, and unknown in 10 (28%), 15 (42%), and 11 (30%) tumors, respectively. Twenty-two (61%) patients received RT. Overall, the four-year event-free survival (EFS) and overall survival (OS) were 70.8% and 88.3%, respectively. Patients with FOXO1 positivity who received RT had superior EFS compared with those who did not (77.8% vs 16.7%; P = 0.03). Among 10 patients who were FOXO1 negative, the outcome was similar with or without RT. CONCLUSIONS: Although limited by a small sample size, data from this study support the routine use of adjuvant RT in patients with FOXO1-positive disease even after complete resection. Additionally, omitting adjuvant RT is rational for patients with FOXO1-negative ARMS and will be prospectively investigated in the current COG trial ARST1431.

Embryonal and Alveolar Rhabdomyosarcoma in Adults: Real-Life Data From a Tertiary Sarcoma Centre.

AIMS: Embryonal and alveolar rhabdomyosarcoma (ERMS, ARMS) are subtypes of RMS that mainly occur in children, with relatively good outcomes. The incidence in adults is extremely low and survival is significantly worse compared with children. Data are scarce and literature generally combines all RMS subtypes, including pleomorphic RMS, which primarily occurs in adults and behaves more like undifferentiated pleomorphic sarcoma. The aim of this study was to evaluate patient and tumour characteristics, outcome and prognostic factors in adult patients with ERMS and ARMS. MATERIALS AND METHODS: All adult (18 years or older) ERMS and ARMS patients (presenting 1990-2016) were identified from a prospectively maintained database and were included in this analysis. RESULTS: Overall, 66 patients were included (42 men, 24 women). The median age at presentation was 28 years (range 18-71). The median overall survival for all ARMS (n = 42) and ERMS (n = 24) patients was 18 months, with a 5-year overall survival rate of 27%. Patients presenting with localised disease (n = 38, 58%) and metastatic disease (n = 25, 42%), had a 5-year overall survival rate of 36% and 11%, respectively. In univariate analysis we found alveolar subtype, fusion gene positivity, infiltrative tumour and metastatic presentation to be negative prognostic factors. CONCLUSION: Survival in adult ERMS and ARMS patients is poor and the current data may be useful in the design of trials with novel agents. Ideally, paediatric and adult oncologists should set up trials together to get a better understanding of biological, genetic and clinically relevant factors in this disease.

Vinorelbine and continuous low-dose cyclophosphamide as maintenance chemotherapy in patients with high-risk rhabdomyosarcoma (RMS 2005): a multicentre, open-label, randomised, phase 3 trial.

BACKGROUND: For more than three decades, standard treatment for rhabdomyosarcoma in Europe has included 6 months of chemotherapy. The European paediatric Soft tissue sarcoma Study Group (EpSSG) aimed to investigate whether prolonging treatment with maintenance chemotherapy would improve survival in patients with high-risk rhabdomyosarcoma. METHODS: RMS 2005 was a multicentre, open-label, randomised, controlled, phase 3 trial done at 102 hospitals in 14 countries. We included patients aged 6 months to 21 years with rhabdomyosarcoma who were considered to be at high risk of relapse: those with non-metastatic incompletely resected embryonal rhabdomyosarcoma occurring at unfavourable sites with unfavourable age (≥10 years) or tumour size (>5 cm), or both; those with any non-metastatic rhabdomyosarcoma with nodal involvement; and those with non-metastatic alveolar rhabdomyosarcoma but without nodal involvement. Patients in remission after standard treatment (nine cycles of ifosfamide, vincristine, dactinomycin with or without doxorubicin, and surgery or radiotherapy, or both) were randomly assigned (1:1) to stop treatment or continue maintenance chemotherapy (six cycles of intravenous vinorelbine 25 mg/m2 on days 1, 8, and 15, and daily oral cyclophosphamide 25 mg/m2, on days 1-28). Randomisation was done by use of a web-based system and was stratified (block size of four) by enrolling country and risk subgroup. Neither investigators nor patients were masked to treatment allocation. The primary outcome was disease-free survival in the intention-to-treat population. Secondary outcomes were overall survival and toxicity. This trial is registered with EudraCT, number 2005-000217-35, and ClinicalTrials.gov, number NCT00339118, and follow-up is ongoing. FINDINGS: Between April 20, 2006, and Dec 21, 2016, 371 patients were enrolled and randomly assigned to the two groups: 186 to stop treatment and 185 to receive maintenance chemotherapy. Median follow-up was 60·3 months (IQR 32·4-89·4). In the intention-to-treat population, 5-year disease-free survival was 77·6% (95% CI 70·6-83·2) with maintenance chemotherapy versus 69·8% (62·2-76·2) without maintenance chemotherapy (hazard ratio [HR] 0·68 [95% CI 0·45-1·02]; p=0·061), and 5-year overall survival was 86·5% (95% CI 80·2-90·9) with maintenance chemotherapy versus 73·7% (65·8-80·1) without (HR 0·52 [95% CI 0·32-0·86]; p=0·0097). Toxicity was manageable in patients who received maintenance chemotherapy: 136 (75%) of 181 patients had grade 3-4 leucopenia, 148 (82%) had grade 3-4 neutropenia, 19 (10%) had anaemia, two (1%) had thrombocytopenia, and 56 (31%) had an infection. One (1%) patient had a grade 4 non-haematological toxicity (neurotoxicity). Two treatment-related serious adverse events occurred: one case of inappropriate antidiuretic hormone secretion and one of a severe steppage gait with limb pain, both of which resolved. INTERPRETATION: Adding maintenance chemotherapy seems to improve survival for patients with high-risk rhabdomyosarcoma. This approach will be the new standard of care for patients with high-risk rhabdomyosarcoma in future EpSSG trials. FUNDING: Fondazione Città della Speranza, Association Léon Berard Enfant Cancéreux, Clinical Research Hospital Program (French Ministry of Health), and Cancer Research UK.

Outcome and Patterns of Relapse in Childhood Parameningeal Rhabdomyosarcoma Treated With Proton Beam Therapy.

PURPOSE: The standard of care of childhood parameningeal rhabdomyosarcoma (pRMS) is chemotherapy and local radiation therapy. Protons are increasingly being used to decrease late effects. The aim of the present study is to analyze the pattern of relapse and the correlation with dosimetric factors in pRMS treated with proton therapy. METHODS AND MATERIALS: This retrospective evaluation includes children treated in our institution for pRMS. Information on demographics, treatment, tumor characteristics, and toxicities and outcome was prospectively collected within the in-house registry. For patients presenting with local relapse, a fusion of the dosimetry with magnetic resonance imaging displaying site and geometry of recurrence was performed. RESULTS: Median follow-up time was 2.9 years (0.5-4.7). Forty-six patients were identified in our institution between July 2013 and November 2017. Main characteristics of patients were as follows: 56.5% male, median age 5.1 years (1.3-17.5), 39.1% alveolar histology, 26.1%, 52.2%, 8.7%, and 13% patients with subgroup risk classification D, E/F/G, H, or metastatic, respectively, median total prescribed dose 55.8 Gy (50.4-56.4). Estimated 2-year local control, metastasis-free survival, event-free survival, and overall survival were 83.8%, 87.8%, 76.9%, and 88.9%, respectively. No acute or late local toxicity exceeding grade 3 was observed. Risk-group was identified as prognostic factor for metastasis-free survival in univariate analysis but not in multivariate analysis (trend: P = .09). In this cohort, dosimetric factors did not correlate with outcome. Isolated local failure happened in 5 of the 11 relapses. Local relapses were matched with dosimetry for 6 patients: 4 of them occurred in the high dose volume and 2 in the intermediate or low dose volume. CONCLUSIONS: Proton therapy was effective and well feasible even in a critical cohort. Still, local relapse within the target volume of the radiation therapy remains an important issue in pRMS and new treatment strategies are needed.

Epidemiology, Incidence, and Survival of Rhabdomyosarcoma Subtypes: SEER and ICES Database Analysis.

Rhabdomyosarcoma is the most common soft-tissue sarcoma in children and adolescents and accounts for 3% of all pediatric tumors. Subtypes include alveolar, spindle cell, embryonal, mixed-type, pleomorphic, and rhabdomyosarcoma with ganglionic differentiation. The National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database was queried for patients diagnosed with any type of rhabdomyosarcoma between 1973 and 2014. Patient demographics, tumor characteristics, and incidence were studied with χ2 analysis. Survival was modeled with Kaplan-Meier survival curves and Cox proportional hazards models were used to assess the effect of age and gender on survival. Pleomorphic subtype had higher grade and larger sized tumors compared to other subtypes (p < 0.05). Pleomorphic and alveolar rhabdomyosarcoma had the worst overall survival with a 26.6% and 28.9% 5-year survival, respectively. Embryonal rhabdomyosarcoma had the highest 5-year survival rate (73.9%). Tumor size was negatively correlated with survival months, indicating patients with larger tumors had shorter survival times (p < 0.05). Presence of higher-grade tumors and metastatic disease at presentation were negatively correlated with survival months (p < 0.05). No significant differences in the survival were found between gender or race between all of the subtypes (p > 0.05). This study highlights key differences in the demographic and survival rates of the different types of rhabdomyosarcoma that can be used for more tailored patient counseling. We also demonstrate that large, population-level databases provide sufficient data that can be used in the analysis of rare tumors. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2226-2230, 2019.

Tumour expressions of hypoxic markers predict the response to neo-adjuvant chemotherapy in children with inoperable rhabdomyosarcoma.

Objective: The study was to assess whether tumour expressions of hypoxia-inducible factor (HIF)-1α, glucose transporter (GLUT)-1, carbonic anhydrase (CA) IX and vascular endothelial growth factor (VEGF) predict response to neo-adjuvant chemotherapy (naCHT) in children with inoperable rhabdomyosarcoma (RMS). Methods: Immunohistochemical expressions of hypoxia markers were determined semi-quantitatively in tumour tissue microarray of 46 patients with embryonal RMS (RME) and 20 with alveolar (RMA), treated with CWS protocols (1992-2013). Results: In paediatric RME, response to naCHT was influenced significantly by tumour expression of CA IX and GLUT-1. Patients with RMA with low expressions of analysed markers responded well to naCHT, while all poor-responders expressed highly hypoxia markers. Only 5.88% of RMA and 11.11% of RME tumours did not express any of the proteins. In both RME and RMA subgroups, most poor-responders demonstrated simultaneous high expression of ≥3 markers, while most patients expressing ≤2 markers responded well to naCHT. In the whole cohort, co-expression of ≥3 markers, was the only independent factor predicting poor-response to chemotherapy (odds ratio 14.706; 95% CI 1.72-125.75; p = 0.014). Conclusions: Immunohistochemical expression pattern of four endogenous markers of hypoxia, in tumour tissue at diagnosis, emerges as a promising tool to predict response to naCHT in children with inoperable RMS.

Worse Outcomes for Head and Neck Rhabdomyosarcoma Secondary to Reduced-Dose Cyclophosphamide.

PURPOSE: Recent trends, including the use of proton therapy and administration of reduced doses of cyclophosphamide, have been adapted in head and neck (HN) rhabdomyosarcoma (RMS) to reduce late morbidity. Our primary goal was to analyze local control and survival outcomes after photon versus proton irradiation in pediatric patients with HN-RMS, with the secondary goal of analyzing the effect of cyclophosphamide dose on disease outcomes. METHODS AND MATERIALS: This single-institution cohort study comprised 76 pediatric HN-RMS patients treated with definitive chemoradiation from 2000 to 2018. Fifty-one patients (67%) received intensity modulated photon radiation therapy, and 25 (33%) received proton therapy. RESULTS: Local failure (LF) at 2 years was 12.5% for parameningeal RMS and 0% for orbital RMS and other head and neck sites (P = .24). Patients treated with protons were more likely to have received reduced-dose cyclophosphamide (P < .0001). The 2-year LF was 7.9% in the intensity modulated photon radiation therapy cohort versus 14.6% in the proton cohort (P = .07), with no difference in survival outcomes. Cumulative cyclophosphamide dose was significantly associated with 2-year LF: 0% for cumulative dose of >20 g/m2 versus 15.3% for ≤20 g/m2 (P = .04). In parameningeal RMS patients (n = 59), both cumulative cyclophosphamide dose and dose intensity were associated with LF (P = .01). There was a trend toward worse event-free survival for parameningeal RMS patients who received reduced-dose-intensity cyclophosphamide (59.2% vs 70.6%, P = .11). CONCLUSIONS: Both dose-intensity and cumulative cyclophosphamide dose seem to play an important role in achieving local control for HN-RMS patients treated with either protons or photons. Longer follow-up is needed to further assess disease outcomes with proton therapy.

Regional Nodal Control for Head and Neck Alveolar Rhabdomyosarcoma.

PURPOSE: To assess clinical outcomes and patterns of failure, particularly regional nodal control, for pediatric patients treated with proton beam therapy (PBT) for head and neck alveolar rhabdomyosarcoma (HN-ARMS). MATERIALS AND METHODS: Between 2006 and 2015, 14 patients with HN-ARMS were enrolled in a prospective registry protocol and treated with PBT at a single institution. Of the patients, 8 (57%) presented with localized disease and 6 (43%) with regional nodal metastases. All patients were treated with systemic therapy per accepted cooperative group regimens. All patients received PBT to the primary site and involved nodal disease with a median dose of 50.4 Gy (relative biological effectiveness). Elective nodal irradiation was not delivered. RESULTS: The median follow-up period for surviving patients was 4.3 years. The 5-year overall survival and disease-free survival rates for the cohort (N = 14) were 45% and 25%, respectively. There were 10 relapses in the cohort: 7 regional nodal, 1 combination local and regional nodal, and 2 leptomeningeal. In 6 of 8 patients (75%) with no nodal disease at diagnosis, isolated regional nodal relapse developed. All nodal relapses occurred in first-echelon draining lymph node basins relative to the primary tumor site. Of 6 patients who presented with nodal metastases, 2 had regional nodal relapse; both of these nodal relapses occurred in the same nodal basin that was initially involved by disease but was not completely targeted as part of the primary treatment plan. CONCLUSIONS: High rates of regional nodal relapse are observed for HN-ARMS patients, including patients with no nodal disease at diagnosis. These data suggest that HN-ARMS patients may benefit from elective nodal irradiation to treat at-risk draining lymph node stations relative to the primary tumor site. We further recommend coverage of the entire nodal level for any sites of initial nodal disease at diagnosis, given the high risk of failure at these sites.

Sinonasal Tract Alveolar Rhabdomyosarcoma in Adults: A Clinicopathologic and Immunophenotypic Study of Fifty-Two Cases with Emphasis on Epithelial Immunoreactivity.

Sinonasal tract (SNT) alveolar rhabdomyosarcoma (ARMS) are frequently misdiagnosed, especially in adults. Fifty-two adult (≥18 years) patients with SNT ARMS were reviewed and characterized by immunohistochemistry and molecular studies. Twenty-six females and 26 males (18-72 years; mean 43.2 years), presented after a short duration (mean 2.6 months) with a large (mean 5.5 cm) destructive nasal cavity mass, involving multiple contiguous paranasal sites (n = 46) and with cervical adenopathy (n = 41). The tumors showed an alveolar, nested to solid growth pattern below an intact, but often involved (n = 9) epithelium with frequent necrosis (n = 37), destructive bone invasion (n = 30), and lymphovascular invasion (n = 25). The neoplastic cells were dyshesive and dilapidated, with crush artifacts. Rhabdoid features (n = 36) and tumor cell multinucleation (n = 28) were common. Mitotic counts were high (mean 17/10 HPFs). The neoplastic cells showed the following immunohistochemical positive findings: desmin (100%), myogenin (100%), MYOD1 (100%), MSA (96%), SMA (52%), CAM5.2 (50%), AE1/AE3 (36%); other positive markers included S100 protein (27%), CD56 (100%), synaptophysin (35%), and chromogranin (13%). Overall, 54% show epithelial marker reactivity. Molecular studies showed FOXO1 translocations (81%) with PCR demonstrating PAX3 in 72.7% tested. Patients presented with high stage (IV 24; III 26) and metastatic disease (lymph nodes n = 41; distant metastases n = 25) (IRSG grouping). Surgery (n = 16), radiation (n = 41) and chemotherapy (n = 45) yielded an overall survival of 36.1 months (mean; range 2.4-286); 18 alive without disease (mean 69.6 months); 7 alive with disease (mean 11.0 months); 1 dead without disease (63.7 months); and 26 dead with disease (mean 18.5 months). SNT ARMS frequently present in adults as a large, destructive midline mass of short symptom duration, with high stage disease. The alveolar to solid pattern of growth of cells with rhabdoid-plasmacytoid features suggests the diagnosis, but epithelial immunohistochemistry markers are present in 54% of cases, leading to misdiagnosis as carcinomas if muscle markers are not also performed. Overall survival of 36.1 months is achieved with multimodality therapy, but 64% have incurable disease (16.9 months). Mixed anatomic site (p = 0.02) was a significant adverse prognostic indicator, while stage (0.06) and tumor size >5 cm (0.06) approached marginal significance.

Histology, fusion status, and outcome in metastatic rhabdomyosarcoma: A report from the Children's Oncology Group.

BACKGROUND: Distinguishing alveolar rhabdomyosarcoma (ARMS) from embryonal rhabdomyosarcoma (ERMS) has historically been of prognostic and therapeutic importance. However, classification has been complicated by shifting histologic criteria required for an ARMS diagnosis. Children's Oncology Group (COG) studies after IRS-IV, which included the height of this diagnostic shift, showed both an increased number of ARMS and an increase in the proportion of fusion-negative ARMS. Following diagnostic standardization and histologic re-review of ARMS cases enrolled during this era, analysis of low-risk (D9602) and intermediate-risk (D9803) rhabdomyosarcoma (RMS) studies showed that fusion status rather than histology best predicts prognosis for patients with RMS. This analysis remains to be completed for patients with high-risk RMS. PROCEDURE: We re-reviewed cases on high-risk COG studies D9802 and ARST0431 with an enrollment diagnosis of ARMS. We compared the event-free survival (EFS) and overall survival by histology, PAX-FOXO1 fusion, and clinical risk factors (Oberlin score) for patients with metastatic RMS using the log-rank test. RESULTS: Histology re-review resulted in reclassification as ERMS for 12% of D9802 cases and 5% of ARST0431 cases. Fusion-negative RMS had a superior EFS to fusion-positive RMS; however, poorer outcome for metastatic RMS was most related to clinical risk factors including age, primary site, and number of metastatic sites. CONCLUSIONS: In contrast to low- or intermediate-risk RMS, in metastatic RMS, clinical risk factors have the most impact on patient outcome. PAX-FOXO1 fusion is more common in patients with a high Oberlin score, but fusion status is not an independent biomarker of prognosis.

Patterns of Failure in Pediatric Rhabdomyosarcoma After Proton Therapy.

PURPOSE: To report on the patterns of failure in children with rhabdomyosarcoma treated with proton therapy. PATIENTS AND METHODS: Between February 2007 and November 2013, 66 children with a median age of 4.1 years (range, 0.6-15.3 years) diagnosed with nonmetastatic rhabdomyosarcoma were treated with proton therapy. Clinical target volume 1 was defined as the prechemotherapy tumor plus a 1-cm anatomically constrained margin. Clinical target volume 2 was defined as the postchemotherapy tumor (or tumor bed) plus a 0.5-cm anatomically constrained margin, further expanded to encompass potential pathways of spread, including soft tissue infiltrated with tumor at diagnosis. RESULTS: Of the 66 children, 11 developed locally progressive disease at a median of 16 months (range, 14-32 months), for an actuarial 2-year local control rate of 88%. Among the children who progressed, median age and tumor size at diagnosis were 6.7 years (range, 0.6-16 years) and 6 cm (range, 2-8 cm), respectively. Of the recurrences, 64% and 36% were embryonal and alveolar, respectively. Disease progression was observed in 7 (64%) parameningeal, 2 (18%) head and neck (other), and 2 (18%) bladder/prostate subsites. At diagnosis, 8 of 11 patients who developed a recurrence were Intergroup Rhabdomyosarcoma Study stage 3, and all 11 were group III. Of the relapses, 100% (11 of 11) were confirmed as in-field within the composite 95% isodose line. One of the 11 patients (9%) developed a new simultaneous regional nodal recurrence outside of the previously treated radiation field. CONCLUSION: Early data suggest that the sharp dosimetric gradient associated with proton therapy is not associated with an increased risk of marginal failure. Routine use of a 0.5- to 1-cm clinical target volume 1/2 margin with highly conformal proton therapy does not compromise local control in children diagnosed with rhabdomyosarcoma with unfavorable risk features.

Local Control for Intermediate-Risk Rhabdomyosarcoma: Results From D9803 According to Histology, Group, Site, and Size: A Report From the Children's Oncology Group.

PURPOSE: To determine local control according to clinical variables for patients with intermediate-risk rhabdomyosarcoma (RMS) treated on Children's Oncology Group protocol D9803. PATIENTS AND METHODS: Of 702 patients enrolled, we analyzed 423 patients with central pathology-confirmed group III embryonal (n=280) or alveolar (group III, n=102; group I-II, n=41) RMS. Median age was 5 years. Patients received 42 weeks of VAC (vincristine, dactinomycin, cyclophosphamide) or VAC alternating with VTC (T = topotecan). Local therapy with 50.4 Gy radiation therapy with or without delayed primary excision began at week 12 for group III patients. Patients with group I/II alveolar RMS received 36-41.4 Gy. Local failure (LF) was defined as local progression as a first event with or without concurrent regional or distant failure. RESULTS: At a median follow-up of 6.6 years, patients with clinical group I/II alveolar RMS had a 5-year event-free survival rate of 69% and LF of 10%. Among patients with group III RMS, 5-year event-free survival and LF rates were 70% and 19%, respectively. Local failure rates did not differ by histology, nodal status, or primary site, though there was a trend for increased LF for retroperitoneal (RP) tumors (P=.12). Tumors ≥5 cm were more likely to fail locally than tumors <5 cm (25% vs 10%, P=.0004). Almost all (98%) RP tumors were ≥5 cm, with no difference in LF by site when the analysis was restricted to tumors ≥5 cm (P=.86). CONCLUSION: Local control was excellent for clinical group I/II alveolar RMS. Local failure constituted 63% of initial events in clinical group III patients and did not vary by histology or nodal status. The trend for higher LF in RP tumors was related to tumor size. There has been no clear change in local control over RMS studies, including IRS-III and IRS-IV. Novel approaches are warranted for larger tumors (≥5 cm).

Secreted Frizzled-Related Protein 3 (SFRP3) Is Required for Tumorigenesis of PAX3-FOXO1-Positive Alveolar Rhabdomyosarcoma.

PURPOSE: Rhabdomyosarcoma (RMS) is a soft tissue sarcoma associated with the skeletal muscle lineage. Of the two predominant subtypes, known as embryonal (eRMS) and alveolar (aRMS), aRMS has the poorer prognosis, with a five-year survival rate of <50%. The majority of aRMS tumors express the fusion protein PAX3-FOXO1. As PAX3-FOXO1 has proven chemically intractable, this study aims to identify targetable proteins that are downstream from or cooperate with PAX3-FOXO1 to support tumorigenesis. EXPERIMENTAL DESIGN: Microarray analysis of the transcriptomes of human skeletal muscle myoblasts expressing PAX3-FOXO1 revealed alteration of several Wnt pathway gene members, including secreted frizzled related protein 3 (SFRP3), a secreted Wnt pathway inhibitor. Loss-of-function using shRNAs against SFRP3 was used to interrogate the role of SFRP3 in human aRMS cell lines in vitro and conditional murine xenograft systems in vivo. The combination of SFRP3 genetic suppression and the chemotherapeutic agent vincristine was also examined. RESULTS: In vitro, suppression of SFRP3 inhibited aRMS cell growth, reduced proliferation accompanied by a G1 arrest and induction of p21, and induced apoptosis. In vivo, doxycycline-inducible suppression of SFRP3 reduced aRMS tumor growth and weight by more than three-fold, in addition to increasing myogenic differentiation and ß-catenin signaling. The combination of SFRP3 suppression and vincristine was more effective at reducing aRMS cell growth in vitro than either treatment alone, and ablated tumorigenesis in vivo. CONCLUSIONS: SFRP3 is necessary for the growth of human aRMS cells both in vitro and in vivo and is a promising new target for investigation in aRMS.

Prognostic value of PAX3/7-FOXO1 fusion status in alveolar rhabdomyosarcoma: Systematic review and meta-analysis.

PURPOSE: The objective of this systematic review is to provide an unprecedented summary of the prognostic impact of PAX3/7-FOXO1 fusion status in alveolar rhabdomyosarcoma. METHODS: Studies evaluating PAX3/7-FOXO1 fusion gene or its variants as a prognostic marker were systematically searched and comparative meta-analysis of overall survival was carried out. RESULTS: A total of 7 studies comprising 993 patients with rhabdomyosarcoma were included. Three eligible studies showed no significant difference of survival between fusion positive and negative alveolar rhabdomyosarcoma. Four eligible studies showed that PAX3-FOXO1 fusion variant may indicate a lower survival probability than PAX7-FOXO1, although the effect did not reach a level of statistical significance (pooled hazard ratios, 1.66; 95% CI, 0.95-2.89; p=0.07). CONCLUSIONS: There was no significant difference in the overall survival between patients with the positive and negative fusion gene, but there were indications of PAX3-FOXO1 being an unfavorable prognostic factor.