Management and Outcomes of Wilms Tumor With Suprarenal Intravascular Extension: A Pediatric Surgical Oncology Research Collaborative Study.

OBJECTIVE: The purpose of this study was to describe management and outcomes from a contemporary cohort of children with Wilms tumor complicated by inferior vena caval thrombus. BACKGROUND: The largest series of these patients was published almost 2 decades ago. Since then, neoadjuvant chemotherapy has been commonly used to manage these patients, and outcomes have not been reported. METHODS: Retrospective review of 19 North American centers between 2009 and 2019. Patient and disease characteristics, management, and outcomes were investigated and analyzed. RESULTS: Of 124 patients, 81% had favorable histology (FH), and 52% were stage IV. IVC thrombus level was infrahepatic in 53 (43%), intrahepatic in 32 (26%), suprahepatic in 14 (11%), and cardiac in 24 (19%). Neoadjuvant chemotherapy using a 3-drug regimen was administered in 82% and postresection radiation in 90%. Thrombus level regression was 45% overall, with suprahepatic level showing the best response (62%). Cardiopulmonary bypass (CPB) was potentially avoided in 67%. The perioperative complication rate was significantly lower after neoadjuvant chemotherapy [(25%) vs upfront surgery (55%); P =0.005]. CPB was not associated with higher complications [CPB (50%) vs no CPB (27%); P =0.08]. Two-year event-free survival was 93% and overall survival was 96%, higher in FH cases (FH 98% vs unfavorable histology/anaplastic 82%; P =0.73). Neither incomplete resection nor viable thrombus cells affected event-free survival or overall survival. CONCLUSIONS: Multimodal therapy resulted in excellent outcomes, even with advanced-stage disease and cardiac extension. Neoadjuvant chemotherapy decreased the need for CPB to facilitate resection. Complete thrombectomy may not always be necessary.

Let it glow: Intraoperative visualization of pulmonary metastases using pafolacianine, a next-generation fluorescent agent, for young adults undergoing pulmonary metastasectomy.

A new generation of disease-specific molecular imaging agents is poised to revolutionize fluorescence-guided surgery. Pafolacianine has been approved for adult lung and ovarian cancers. We demonstrate a proof of concept for pediatric surgeons treating young adults with pulmonary metastatic sarcomas. Five successful fluorescence-guided pulmonary metastasectomy operations were performed in young adult patients with metastatic osteosarcoma or Ewing sarcoma following administration of pafolacianine. All osteosarcoma lesions identified using standard techniques were also markedly fluorescent in patients. Novel fluorescent molecular agents targeted to tumor-specific receptors have promise of increased sensitivity and specificity for detecting metastatic nodules and enhancing surgical clearance of disease.

Minimally invasive and robotic-assisted approaches applied to pediatric surgical oncology.

The management of pediatric tumors is complex, with surgery, chemotherapy, and radiotherapy being cornerstones in their treatment. Tumor removal is increasingly performed by a minimally invasive approach, which allows for quicker postoperative recovery and less postoperative pain. The goal of this report is to give an overview of minimally invasive surgical approaches for common pediatric tumors, with a focus on technical considerations and postoperative outcomes.

Intercostal nerve cryoablation reduces opioid utilization after thoracotomy in children with cancer.

BACKGROUND: Intercostal nerve cryoablation (INC) has shown promise as an adjunct method for analgesia in adults undergoing thoracotomy, but has yet to be widely used in children for this indication. We hypothesize that INC decreases opioid utilization in children undergoing thoracotomy for cancer operations. METHODS: A retrospective review was performed of children who underwent thoracotomy for cancer diagnosis at a freestanding children's hospital from 2018 to 2023. Patient characteristics, intraoperative data, and data on clinical course were collected. Patients were divided into those who underwent INC and those who underwent routine care for comparison. RESULTS: Twenty-six patients underwent 38 procedures at a median age of 16 years (range 5-21 years). INC was performed in 23 cases over a median of five intercostal levels (range 2-7). Total oral morphine equivalents during inpatient admission were significantly lower in INC patients (137.6 vs. 514.5 mg, p = .002). Routine care patients were more likely to be discharged with an opioid prescription (30.4% vs. 80.0%, p = .008). Length of stay was similar between patients with INC and routine care (4 vs. 5 days, p = .15). There were no differences in rates of reoperation or 30-day re-admission (emergency department or inpatient). CONCLUSTIONS: INC is a feasible and safe adjunct for children undergoing thoracotomy for cancer. INC is associated with reduced postoperative opioid utilization with respect to both inpatient use and outpatient prescriptions.

Children and young adults with newly diagnosed rhabdomyosarcoma metastatic to bone treated on Children's Oncology Group studies.

BACKGROUND: Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. Despite bone metastases being present in 5% of patients at diagnosis, there are limited studies examining these outcomes. We sought to define the prognostic factors, clinical courses, and outcomes of children treated on Children's Oncology Group (COG) clinical trials with RMS metastatic to bone at diagnosis. METHODS: We performed a retrospective analysis of patients diagnosed with bone metastatic RMS enrolled on COG RMS clinical trials (D9802, D9803, ARST0431, or ARST08P1) between 1997 and 2013. RESULTS: RMS metastatic to bone was identified in 154 patients at a median age of 14.9 years at diagnosis. Fifty-eight percent of patients were male, 90% had metastases at additional sites, 74% had alveolar histology, and extremity was the most common primary site (31%). Eighty-six percent of patients (n = 133) received radiation therapy. The 3- and 5-year event-free survival (EFS) was 15.4% and 14.5%, respectively. The 3- and 5-year overall survival (OS) was 30.4% and 18.0%, respectively. We identified alveolar histology, FOXO1 fusion presence, unfavorable primary location, higher Oberlin score, and lack of radiation as poor prognostic characteristics for both EFS and OS in univariate analysis. Lack of radiation was not significant when excluding patients with events prior to 20 weeks. CONCLUSIONS: This study is the largest analysis of patients with bone metastatic RMS, and defines the poor overall outcomes and negative prognostic factors for these patients. They may be eligible for therapy deintensification for improved quality of life or pursuit of novel treatments/approaches, which are desperately needed.

Contemporary surgical management of pediatric non-rhabdomyosarcoma soft tissue sarcoma.

Non-rhabdomyosarcoma soft tissue sarcoma (STS) comprises most STS in pediatric patients. It is a diverse set of over 30 histologic subtypes. Treatment is based on risk group determined by tumor size, grade, and the presence of metastases. Surgical resection is a cornerstone of therapy, as tumors are often resistant to chemotherapy or radiation. While patients with isolated tumors less than 5 cm may undergo upfront resection, strong consideration should be given to neoadjuvant chemoradiotherapy to ensure negative margins at surgical resection and optimal outcomes. Sentinel lymph node biopsy is strongly recommended for clear cell and epithelioid sarcomas. The most common metastatic site is the lung, and metastases should be resected at the end of therapy, when feasible. Unfortunately, many high-risk patients progress on therapy, and alternative strategies including earlier metastatic control require investigation.

Adolescents and young adults with rhabdomyosarcoma: A report from the Soft Tissue Sarcoma Committee of the Children's Oncology Group.

INTRODUCTION: The impact of established prognostic factors on survival outcomes for childhood rhabdomyosarcoma (RMS) have not been well described in the adolescent and young adult (AYA) RMS patient population. METHODS: This is a retrospective analysis of patients with newly diagnosed RMS enrolled between 1997 and 2016 on seven previously reported Children's Oncology Group (COG) clinical trials. Demographics, clinical features, treatment details, and outcome data were collected. Five-year event-free survival (EFS) and overall survival (OS) were estimated for patients diagnosed at age 15-39 years and those diagnosed under age 15 years using the Kaplan-Meier method. Log-rank test was used to compare prognostic factors for EFS and OS. Factors significant in the univariable analysis were included in a Cox proportional hazards regression model. Nonsignificant covariates were removed from the multiple regression model. RESULTS: Total 2151 patients including 402 AYAs were analyzed. AYAs were more likely to present with primary tumors ≥5 cm in size, metastatic disease, alveolar histology, and have FOXO1 fusions compared to children. Five-year EFS for the AYA cohort was 44.2% versus 67% for children (p < .001), and 5-year OS was 52% for the AYA cohort versus 78% for children (p < .001). Multivariable analysis revealed tumor site, size and invasiveness, clinical group, and histology were prognostic in AYAs. CONCLUSION: AYAs with RMS have a poorer prognosis compared to younger children due to multiple factors. Further research focused on AYAs to better understand RMS biology and improve treatments is critical to improve survival.

Late Events Occurring After 5 Years in Pediatric Rhabdomyosarcoma: A Report From the Children's Oncology Group.

Rhabdomyosarcoma is the most common pediatric soft tissue sarcoma, and 5-year overall survival exceeds 70%. With more long-term survivors, it is critical to understand the frequency of late events, including recurrence, second malignant neoplasm, and death, occurring 5 years after diagnosis, and the variables associated with these events. We report late events in patients enrolled on Intergroup Rhabdomyosarcoma Study Group and Children's Oncology Group trials from 1997 to 2013 including D9602, D9803, D9802, ARST0331, ARST0431, ARST0531, and ARST08P1. A late event occurred in 2.9% of 5-year event-free survivors supporting guidelines to limit surveillance for these events to 5 years from diagnosis.

Imaging adjuvants in pediatric surgical oncology.

Surgery is a crucial component of pediatric cancer treatment, but conventional methods may lack precision. Image-guided surgery, including fluorescent and radioguided techniques, offers promise for enhancing tumor localization and facilitating precise resection. Intraoperative molecular imaging utilizes agents like indocyanine green to direct surgeons to occult deposits of tumor and to delineate tumor margins. Next-generation agents target tumors directly to improve specificity. Radioguided surgery, employing tracers like metaiodobenzylguanidine (MIBG), complements fluorescent techniques by allowing for detection of tumors at a greater depth. Dual-labeled agents combining both modalities are under development. Three-dimensional modeling and virtual/augmented reality aid in preoperative planning and intraoperative guidance. The above techniques show great promise to benefit patients with pediatric tumors, and their continued development will almost certainly improve surgical outcomes.

Children's Oncology Group's 2023 blueprint for research: Surgery.

Surgery plays a crucial role in the treatment of children with solid malignancies. A well-conducted operation is often essential for cure. Collaboration with the primary care team is important for determining if and when surgery should be performed, and if performed, an operation must be done in accordance with well-established standards. The long-term consequences of surgery also need to be considered. Indications and objectives for a procedure vary. Providing education and developing and analyzing new research protocols that include aims relevant to surgery are key objectives of the Surgery Discipline of the Children's Oncology Group. The critical evaluation of emerging technologies to ensure safe, effective procedures is another key objective. Through research, education, and advancing technologies, the role of the pediatric surgeon in the multidisciplinary care of children with solid malignancies will continue to evolve.

Management of undifferentiated embryonal sarcoma of the liver: A Pediatric Surgical Oncology Research Collaborative study.

BACKGROUND: Undifferentiated embryonal sarcoma of the liver (UESL) is a rare tumor for which there are few evidence-based guidelines. The aim of this study was to define current management strategies and outcomes for these patients using a multi-institutional dataset curated by the Pediatric Surgical Oncology Research Collaborative. METHODS: Data were collected retrospectively for patients with UESL treated across 17 children's hospitals in North America from 1989 to 2019. Factors analyzed included patient and tumor characteristics, PRETEXT group, operative details, and neoadjuvant/adjuvant regimens. Event-free and overall survival (EFS, OS) were the primary and secondary outcomes, respectively. RESULTS: Seventy-eight patients were identified with a median age of 9.9 years [interquartile range [IQR): 7-12]. Twenty-seven patients underwent resection at diagnosis, and 47 patients underwent delayed resection, including eight liver transplants. Neoadjuvant chemotherapy led to a median change in maximum tumor diameter of 1.6 cm [IQR: 0.0-4.4] and greater than 90% tumor necrosis in 79% of the patients undergoing delayed resection. R0 resections were accomplished in 63 patients (81%). Univariate analysis found that metastatic disease impacted OS, and completeness of resection impacted both EFS and OS, while multivariate analysis revealed that R0 resection was associated with decreased expected hazards of experiencing an event [hazard ratio (HR): 0.14, 95% confidence interval (CI): 0.04-0.6]. At a median follow-up of 4 years [IQR: 2-8], the EFS was 70.0% [95% CI: 60%-82%] and OS was 83% [95% CI: 75%-93%]. CONCLUSION: Complete resection is associated with improved survival for patients with UESL. Neoadjuvant chemotherapy causes minimal radiographic response, but significant tumor necrosis.

Survival outcomes in pediatric patients with metastatic Ewing sarcoma who achieve a rapid complete response of pulmonary metastases.

PURPOSE: Our objectives were to compare overall survival (OS) and pulmonary relapse between patients with metastatic Ewing sarcoma (EWS) at diagnosis who achieve rapid complete response (RCR) and those with residual pulmonary nodules after induction chemotherapy (non-RCR). PATIENTS AND METHODS: This retrospective cohort study included children under 20 years with metastatic EWS treated from 2007 to 2020 at 19 institutions in the Pediatric Surgical Oncology Research Collaborative. Chi-square tests were conducted for differences among groups. Kaplan-Meier curves were generated for OS and pulmonary relapse. RESULTS: Among 148 patients with metastatic EWS at diagnosis, 61 (41.2%) achieved RCR. Five-year OS was 71.2% for patients who achieved RCR, and 50.2% for those without RCR (p = .04), and in multivariable regression among patients with isolated pulmonary metastases, RCR (hazards ratio [HR] 0.42; 95% confidence interval [CI]: 0.17-0.99) and whole lung irradiation (WLI) (HR 0.35; 95% CI: 0.16-0.77) were associated with improved survival. Pulmonary relapse occurred in 57 (37%) patients, including 18 (29%) in the RCR and 36 (41%) in the non-RCR groups (p = .14). Five-year pulmonary relapse rates did not significantly differ based on RCR (33.0%) versus non-RCR (47.0%, p = .13), or WLI (38.8%) versus no WLI (46.0%, p = .32). DISCUSSION: Patients with EWS who had isolated pulmonary metastases at diagnosis had improved OS if they achieved RCR and received WLI, despite having no significant differences in rates of pulmonary relapse.

Association of Prophylactic Antibiotics With Early Infectious Complications in Children With Cancer Undergoing Central Venous Access Device Placement.

OBJECTIVE: To evaluate the impact of prophylactic antibiotics on early infectious complications after central venous access device (VAD) placement in children with cancer. SUMMARY OF BACKGROUND DATA: Despite the frequency of VAD procedures in children, the effectiveness of prophylactic antibiotics for reducing infectious complications is unknown. METHODS: This was a retrospective cohort study of children with cancer undergoing central VAD placement identified in the Pediatric Health Information System database between 2017-2021. The primary outcome was the rate of early infectious complications (composite surgical site infections, central line-associated bloodstream infections, and bacteremia). Multivariable logistic regression was used to evaluate factors associated with early infection, and heterogeneity of treatment effect of prophylactic antibiotics was compared across subgroups. RESULTS: 9,216 patients were included (6,058 ports and 3,158 tunneled lines). Prophylactic antibiotics were associated with lower early infectious complications overall (1.3% vs. 2.4%; OR 0.55 [95% C.I. 0.39-0.79], P<0.001), an effect demonstrated for tunneled lines (OR 0.59, 95% C.I.: 0.41-0.84) but not ports (OR 3.01, 95% C.I.: 0.66-13.78). On multivariate analysis, prophylactic antibiotics (OR 0.67, 95% C.I.: 0.45-0.97) and solid tumors (OR 0.38, 95% C.I.: 0.22-0.64) were associated with reduced odds of early infections, while tunneled lines (OR 20.78, 95% C.I.: 9.83-43.93) and acute myelogenous leukemia (OR 2.37, 95% C.I.: 1.58-3.57) had increased odds. CONCLUSIONS: Prophylactic antibiotics are associated with reduced early infectious complications after central VAD placement overall. Despite recommendations from multiple national organizations against prophylactic antibiotics, these findings suggest a benefit in children with malignancy undergoing tunneled line placement.

Management and outcomes of chest wall rhabdomyosarcoma: A report from the Children's Oncology Group Soft Tissue Sarcoma Committee.

INTRODUCTION: Rhabdomyosarcoma (RMS) of the chest wall presents unique management challenges and local control considerations. The benefit of complete excision is uncertain and must be weighed against potential surgical morbidity. Our aim was to assess factors, including local control modality, associated with clinical outcomes in children with chest wall RMS. METHODS: Forty-four children with RMS of the chest wall from low-, intermediate-, and high-risk Children's Oncology Group studies were reviewed. Predictors of local failure-free survival (FFS), event-free survival (EFS), and overall survival (OS) were assessed, including clinical characteristics and staging, primary tumor anatomic locations, and local control modalities. Survival was assessed by Kaplan-Meier analysis and the log-rank test. RESULTS: Tumors were localized in 25 (57%) and metastatic in 19 (43%), and they involved the intercostal region (52%) or superficial muscle alone (36%). Clinical group was I (18%), II (14%), III (25%), and IV (43%), and ultimately 19 (43%) patients had surgical resection (upfront or delayed), including 10 R0 resections. Five-year local FFS, EFS, and OS were 72.1%, 49.3%, and 58.5%, respectively. Univariate factors associated with local FFS included age, International Rhabdomyosarcoma Study (IRS) group, extent of surgical excision, tumor size, superficial tumor location, and presence of regional or metastatic disease. Other than tumor size, the same factors were associated with EFS and OS. CONCLUSIONS: Chest wall RMS has variable presentation and outcome. Local control is a significant contributor to EFS and OS. Complete surgical excision, whether upfront or after induction chemotherapy, is usually only possible for smaller tumors confined to the superficial musculature but is associated with improved outcomes. While overall outcomes remain poor for patients with initially metastatic tumors, regardless of local control modality, complete excision may be beneficial for patients with localized tumors if it can be achieved without excess morbidity.

Prognosis of children and young adults with newly diagnosed rhabdomyosarcoma metastatic to bone marrow treated on Children's Oncology Group studies.

BACKGROUND: Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. Metastatic disease occurs in 16% of all RMS cases and has a poor prognosis. There are limited studies examining the outcomes specific to patients with RMS metastatic to bone marrow despite an incidence of 6% at diagnosis. Our study aims to document the outcomes, prognostic factors, and clinical courses of children presenting with RMS metastatic to bone marrow treated on Children's Oncology Group (COG) cooperative trials. METHODS: We performed a retrospective analysis of the patients diagnosed with RMS metastatic to bone marrow between 1997 and 2013 enrolled on one of four COG RMS clinical trials of D9802, D9803, ARST0431, and ARST08P1. RESULTS: We identified 179 cases with RMS metastatic to bone marrow. Patients had a median age of 14.8 years, 58% were male, predominantly alveolar histology (76%), extremity was the most common primary site (32%), and 87% had metastatic disease to additional sites; 83% (n = 149) received radiation as a treatment modality. The 3- and 5-year event-free survival was 9.4% and 8.2%, respectively. The 3- and 5-year overall survival was 26.1% and 12.6%, respectively. Age ≥10 years, alveolar histology, FOXO1 fusion presence, unfavorable primary location, higher Oberlin score, and lack of radiation were identified as poor prognostic/predictive characteristics. CONCLUSIONS: This study represents the largest analysis of RMS metastatic to bone marrow, defining the poor prognostic outcome for these patients. These patients may be eligible for therapy deintensification or early pursuit of novel treatments/approaches that are desperately needed.

Local treatment of rhabdomyosarcoma of the female genital tract: Expert consensus from the Children's Oncology Group, the European Soft-Tissue Sarcoma Group, and the Cooperative Weichteilsarkom Studiengruppe.

The International Soft-Tissue Sarcoma Consortium (INSTRuCT) was founded as an international collaboration between different pediatric soft-tissue sarcoma cooperative groups (Children's Oncology Group, European Pediatric Soft-Tissue Sarcoma Group, and Cooperative Weichteilsarkom Studiengruppe). Besides other tasks, a major goal of 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. Therefore, a 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 were that 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. In 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 of these patients in different study groups.

Multi-institutional assessment of the prevalence of neuroendocrine tumors in children undergoing laparoscopic appendectomy for acute appendicitis in the United States.

As non-operative management of acute appendicitis in children has become more common, missed incidental appendiceal pathology can be an unintended consequence. We assessed the prevalence of neuroendocrine tumors in appendectomy specimens from eight US children's hospitals from 2012 to 2021. The prevalence of neuroendocrine tumors (NET) was found to be 1:271, with a median age of 14 years and 62% female. Most tumors were small (median 6 mm; interquartile range [IQR]: 3-10), and no recurrence was noted during the follow-up period (median 22.5 months; IQR: 3-53). The possibility of delayed diagnosis of these tumors should be part of the discussion for non-operative management of pediatric acute appendicitis.

Indocyanine green fluorescence imaging as an adjunct for the localization of a bile leak after split liver transplantation.

BACKGROUND: The intraoperative identification of a bile leak after liver transplantation can be challenging, especially when using technical variant grafts. Possible sources of leakage include the sometimes multiple biliary anastomoses or orphan ducts leading to cut surface leak. Preoperative imaging is often unable to precisely identify the location of the leak. Indocyanine green (ICG) fluorescence imaging has been utilized in adult hepatobiliary and transplant surgery, but not for the management of postoperative biliary complications. METHODS: We present a case where ICG fluorescence imaging was used to identify a cut surface bile leak after pediatric split liver transplantation. RESULTS: A 5-year-old girl with methylmalonic acidemia underwent a left lobe split liver transplantation. A single Roux-en-Y choledochojejunostomy was performed. Nine days after transplant, bile was noted in the surgical drain. Imaging confirmed the patency of the hepatic artery and the absence of intraabdominal collection. A hepatobiliary iminodiacetic acid scan showed the majority of radiotracer was excreted through the surgical drain. The patient was explored surgically: 4.5× loupe magnification did not allow for the localization of the leak. ICG was administered intravenously, after which a cut surface bile leak could be identified and repaired. There was no recurrence of bile leak after repair. Eighteen months after transplant, the patient is alive and well and has not suffered from any additional biliary complications. CONCLUSION: Indocyanine green constitutes an additional tool in the arsenal of measures available to facilitate the intraoperative detection and management of bile leaks occurring after pediatric technical variant graft transplant.

Incidence and management of pleural effusions in patients with Wilms tumor: A Pediatric Surgical Oncology Research Collaborative study.

Wilms tumor (WT) is the most common renal malignancy in children. Children with favorable histology WT achieve survival rates of over 90%. Twelve percent of patients present with metastatic disease, most commonly to the lungs. The presence of a pleural effusion at the time of diagnosis of WT may be noted on staging imaging; however, minimal data exist regarding the significance and prognostic importance of this finding. The objectives of our study are to identify the incidence of pleural effusions in patients with WT, and to determine the potential impact on oncologic outcomes. A multi-institutional retrospective review was performed from January 2009 to December 2019, including children with WT and a pleural effusion on diagnostic imaging treated at Pediatric Surgical Oncology Research Collaborative (PSORC) participating institutions. Of 1259 children with a new WT diagnosis, 94 (7.5%) had a pleural effusion. Patients with a pleural effusion were older than those without (median 4.3 vs 3.5 years; P = .004), and advanced stages were more common (local stage III 85.9% vs 51.9%; P < .0001). Only 14 patients underwent a thoracentesis for fluid evaluation; 3 had cytopathologic evidence of malignant cells. Event-free and overall survival of all children with WT and pleural effusions was 86.2% and 91.5%, respectively. The rate and significance of malignant cells present in pleural fluid is unknown due to low incidence of cytopathologic analysis in our cohort; therefore, the presence of an effusion does not appear to necessitate a change in therapy. Excellent survival can be expected with current stage-specific treatment regimens.

Inflammatory myofibroblastic tumor: A multi-institutional study from the Pediatric Surgical Oncology Research Collaborative.

Inflammatory myofibroblastic tumor (IMT) is a mesenchymal neoplasm of intermediate malignancy. We describe the largest cohort of IMT patients to date, aiming to further characterize this rare, poorly understood tumor. This is a multi-institutional review of IMT patients ≤39 years, from 2000 to 2018, at 18 hospitals in the Pediatric Surgical Oncology Research Collaborative. One hundred and eighty-two patients were identified with median age of 11 years. Thirty-three percent of tumors were thoracic in origin. Presenting signs/symptoms included pain (29%), respiratory symptoms (25%) and constitutional symptoms (20%). Median tumor size was 3.9 cm. Anaplastic lymphoma kinase (ALK) overexpression was identified in 53% of patients. Seven percent of patients had distant disease at diagnosis. Ninety-one percent of patients underwent resection: 14% received neoadjuvant treatment and 22% adjuvant treatment. Twelve percent of patients received an ALK inhibitor. Sixty-six percent of surgical patients had complete resection, with 20% positive microscopic margins and 14% gross residual disease. Approximately 40% had en bloc resection of involved organs. Median follow-up time was 36 months. Overall 5-year survival was 95% and 5-year event-free survival was 80%. Predictors of recurrence included respiratory symptoms, tumor size and distant disease. Gross or microscopic margins were not associated with recurrence, suggesting that aggressive attempts at resection may not be warranted.