Surgical Management of Wilms Tumors with Intravenous Extension: A Multicenter Analysis of Clinical Management with Technical Insights.

BACKGROUND: About 5% of Wilms tumors present with vascular extension, which sometimes extends to the right atrium. Vascular extension does not affect the prognosis, but impacts the surgical strategy, which is complex and not fully standardized. Our goal is to identify elements of successful surgical management of Wilms tumors with vascular extensions. PATIENTS AND METHODS: A retrospective study of pediatric Wilms tumors treated at three sites (January 1999-June 2019) was conducted. The inclusion criterion was the presence of a renal vein and vena cava thrombus at diagnosis. Tumor stage, pre and postoperative treatment, preoperative imaging, operative report, pathology, operative complications, and follow-up data were reviewed. RESULTS: Of the 696 pediatric patients with Wilms tumors, 69 (9.9%) met the inclusion criterion. In total, 24 patients (37.5%) had a right atrial extension and two presented with Budd-Chiari syndrome at diagnosis. Two died at diagnosis owing to pulmonary embolism. All patients received neoadjuvant chemotherapy and thrombus regressed in 35.6% of cases. Overall, 14 patients had persistent intra-atrial thrombus extension (58%) and underwent cardiopulmonary bypass. Most thrombi (72%) were removed intact with nephrectomy. Massive intraoperative bleeding occurred during three procedures. Postoperative renal insufficiency was identified as a risk factor for patient survival (p = 0.01). With a median follow-up of 9 years (range: 0.5-20 years), overall survival was 89% and event-free survival was 78%. CONCLUSIONS: Neoadjuvant chemotherapy with proper surgical strategy resulted in a survival rate comparable to that of children with Wilms tumors without intravascular extension. Clinicians should be aware that postoperative renal insufficiency is associated with worse survival outcomes.

Childhood cancer surgery in low- and middle-income countries.

This report summarizes the status of pediatric surgical oncology services in low- and middle-income countries. Factors such as surgical capacity and enablers, and barriers to providing pediatric surgical oncology services are discussed. A review of the literature was conducted to examine the evidence for the capacity of low- and middle-income countries to provide childhood cancer surgery services, focusing on general surgery. Unpublished, ongoing work and initiatives of international organizations are also described.

Current surgical approaches to pediatric renal tumors.

Pediatric renal tumors are among the most common pediatric solid malignancies. Surgical resection is a key component in the multidisciplinary therapy for children with kidney tumors. Therefore, it is imperative that surgeons caring for children with renal tumors fully understand the current standards of care in order to provide appropriate surgical expertise within this multimodal framework. Fortunately, the last 60 years of international, multidisciplinary pediatric cancer cooperative group studies have enabled high rates of cure for these patients. This review will highlight the international surgical approaches to pediatric patients with kidney cancer to help surgeons understand the key differences and similarities between the European (International Society of Pediatric Oncology) and North American (Children's Oncology Group) recommendations.

Image-guided core-needle or surgical biopsy for neuroblastoma diagnosis in children: A systematic review and meta-analysis from the International Society of Pediatric Surgical Oncology (IPSO).

BACKGROUND: Image-guided core-needle biopsy (IGCNB) is a widely used and valuable clinical tool for tissue diagnosis of pediatric neuroblastoma. However, open surgical biopsy remains common practice even if children undergo more invasive and painful procedures. This review aims to determine the diagnostic accuracy and safety of IGCNBs in pediatric patients with neuroblastoma. METHODS: We conducted a systematic review of peer-reviewed original articles published between 1980 and 2023, by searching "pediatric oncology," "biopsy," "interventional radiology," and "neuroblastoma." Exclusion criteria were patients older than 18 years, studies concerning non-neurogenic tumors, case reports, and language other than English. Both the systematic review and meta-analysis were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. RESULTS: A total of 533 abstracts articles were analyzed. Of these, eight retrospective studies met inclusion criteria (490 infants, 270 surgical biopsies [SB], 220 image-guided biopsies). Tissue adequacy for primary diagnosis (SB: n = 265, 98%; IGCNB: n = 199, 90%; p = .1) and biological characterization (SB: n = 186, 95%; IGCNB: n = 109, 89%; p = .15) was similar with both biopsy techniques, while intraoperative transfusion rate (SB: n = 51, 22%; IGCNB: n = 12, 6%; p = .0002) and complications (%) (SB: n = 58, 21%; IGCNB: n = 14, 6%; p = .005) were higher with surgical biopsy. Length of stay was similar in both groups; however, no additional data about concurrent diagnostic or treatment procedures were available in the analyzed studies. CONCLUSIONS: IGCNB is a safe and effective strategic approach for diagnostic workup of NB and should be considered in preferance to SB wherever possible.

A subset of image-defined risk factors predict completeness of resection in children with high-risk neuroblastoma: An international multicenter study.

BACKGROUND: Image-defined risk factors (IDRFs) were promulgated for predicting the feasibility and safety of complete primary tumor resection in children with neuroblastoma (NB). There is limited understanding of the impact of individual IDRFs on resectability of the primary tumor or patient outcomes. A multicenter database of patients with high-risk NB was interrogated to answer this question. DESIGN/METHODS: Patients with high-risk NB (age <20 years) were eligible if cross-sectional imaging was performed at least twice prior to resection. IDRFs and primary tumor measurements were recorded for each imaging study. Extent of resection was determined from operative reports. RESULTS: There were 211 of 229 patients with IDRFs at diagnosis, and 171 patients with IDRFs present pre-surgery. A ≥90% resection was significantly more likely in the absence of tumor invading or encasing the porta hepatis, hepatoduodenal ligament, superior mesenteric artery (SMA), renal pedicles, abdominal aorta/inferior vena cava (IVC), iliac vessels, and/or diaphragm at diagnosis or an overlapping subset of IDRFs (except diaphragm) at pre-surgery. There were no significant differences in event-free survival (EFS) and overall survival (OS) when patients were stratified by the presence versus absence of any IDRF either at diagnosis or pre-surgery. CONCLUSION: Two distinct but overlapping subsets of IDRFs present either at diagnosis or after induction chemotherapy significantly influence the probability of a complete resection in children with high-risk NB. The presence of IDRFs was not associated with significant differences in OS or EFS in this cohort.

Management of Chyle Leak in Pediatric Surgical Oncology: A Systematic Review.

INTRODUCTION: Chyle leak, a rare complication, arises from damage to primary lymphatic vessels due to congenital factors or medical interventions, leading to conditions such as chylothorax and chylous ascites. Managing chyle leaks is challenging, especially in pediatric surgical oncology, often arising as postoperative complications. Treatment options range from conservative dietary adjustments to surgical interventions, depending on leak severity and patient condition. This systematic review examines the management of chyle leaks in pediatric surgical oncology, emphasizing both conservative and surgical approaches. METHODS: This systematic review involved extensive database searches (EMBASE, Web of Science, and PubMed) to identify relevant studies on chyle leak management in the pediatric population. The review included studies from 1982 to 2023 and focused on pediatric and adolescent patients, assessing various treatment approaches and outcomes. Nine articles composed of 163 patients (study population size ranging from 2 to 82 patients). Independent reviewers evaluated the selected studies for inclusion. RESULTS: Among 9 articles analyzed, 98.8% of pediatric patients initially received conservative management for chyle leaks, with 11.7% eventually requiring surgical intervention due to persistent leaks (8, 10, and 16 to 22). Neuroblastoma resection is associated with 20% to 40% rate of chyle leak, and the extent of lymphadenectomy has been identified as a risk factor for chyle leak. The study highlighted variability in clinical success rates based on conservative management approaches. DISCUSSION: Chyle leak, while rare, presents a complex challenge, especially in pediatric surgical oncology. Various causes and treatment options exist, with a preference for conservative management initially and surgical intervention in specific circumstances. Factors such as leak severity and patient condition guide the choice between approaches. However, the scarcity of comparative data and randomized trials in the pediatric population necessitates further research to establish optimal management strategies for chyle leaks. CONCLUSIONS: Conservative management of chyle leaks has proven to be the preferred approach in early stages of treatment, whereas surgical management could be the preferred choice in certain situations. Larger prospective studies are needed to further evaluate these results.

Congenital lung malformations: a nationwide survey on management aspects by the Italian Society of Pediatric Surgery.

INTRODUCTION: Over the years, congenital lung malformations (CLM) management remains a controversial topic in pediatric thoracic surgery. The Italian Society of Pediatric Surgery performed a national survey to study the current management variability among centers, trying to define national guidelines and a standardized approach of children with congenital lung malformations. METHODS: Following a National Society approval, an electronic survey including 35 items on post-natal management was designed, focusing on surgical, anesthesiology, radiology and pneumology aspects. The survey was conducted contacting all pediatric surgical units performing thoracic surgery. RESULTS: 39 pediatric surgery units (97.5%) participated in the study. 13 centers (33.3%) were classified as high-volume (Group A), while 26 centers (66.7%) were low volume (Group B). Variances in diagnostic imaging protocols were observed, with Group A performing fewer CT scans compared to Group B (p = 0.012). Surgical indications favored operative approaches for asymptomatic CLM and pulmonary sequestrations in both groups, while a wait-and-see approach was common for congenital lobar emphysema. Surgical timing for asymptomatic CLM differed significantly, with most high-volume centers operating on patients younger than 12 months (p = 0.02). Thoracoscopy was the preferred approach for asymptomatic CLM in most of centers, while postoperative long-term follow-up was not performed in most of the centers. CONCLUSION: Thoracoscopic approach seems uniform in asymptomatic CLM patients and variable in symptomatic children. Lack of uniformity in surgical timing and preoperative imaging assessment has been identified as key areas to establish a common national pattern of care for CLM.

Minimally invasive approach of paediatric neuroblastoma with thoracic vascular encasement.

ABSTRACT: Neuroblastoma (NB) is the most frequent paediatric extracranial solid tumour. The surgical management of these tumours in newborns changed recently, performing resections in cases with tumour size increase after birth. Minimally invasive procedures were mostly reported in cases without pre-operative image-defined risk factors (IDRFs), defined by vascular and organ involvement. Thoracoscopic resection represents a minority of the overall surgical procedures for neuroblastic tumour management, as the posterior mediastinum is one of the least frequent locations of NB. A thoracoscopic resection was performed on a 22-month-old child with a NB encasing the aorta and a 6-month-old child with the encasement of the left subclavian and vertebral artery. A step-by-step minimally invasive procedure was described, highlighting anatomical landmarks and dissection techniques. The described technique was performed in 130 min. Thoracoscopic resection provided a macroscopic resection without surgical complications and patient was discharged on the 3 rd post-operative day. The study shows a feasible and safe thoracoscopic approach for paediatric thoracic NB with IDRFs.

Identification of Pediatric Tumors Intraoperatively Using Indocyanine Green (ICG).

BACKGROUND: Fluorescence-guided surgery (FGS) with indocyanine green (ICG) is increasingly applied in pediatric surgical oncology. However, FGS has been mostly reported in case studies of liver or renal tumors. Applying novel technologies in pediatric surgical oncology is more challenging than in adult surgical oncology due to differences in tumor histology, biology, and fewer cases. No consensus exists on ICG-guided FGS for surgically managing pediatric solid tumors. Therefore, we reviewed the literature and discuss the limitations and prospects of FGS. METHODS: Using PRISMA guidelines, we analyzed articles on ICG-guided FGS for childhood solid tumors. Case reports, opinion articles, and narrative reviews were excluded. RESULTS: Of the 108 articles analyzed, 17 (14 retrospective and 3 prospective) met the inclusion criteria. Most (70.6%) studies used ICG to identify liver tumors, but the timing and dose of ICG administered varied. Intraoperative outcomes, sensitivity and specificity, were reported in 23.5% of studies. Fluorescence-guided liver resections resulted in negative margins in 90-100% of cases; lung metastasis was detected in 33% of the studies. In otolaryngologic malignancies, positive margins without fluorescence signal were reported in 25% of cases. Overall, ICG appeared effective and safe for lymph node sampling and nephron-sparing procedures. CONCLUSIONS: Despite promising results from FGS, ICG use varies across the international pediatric surgical oncology community. Underreported intraoperative imaging outcomes and the diversity and rarity of childhood solid tumors hinder conclusive scientific evidence supporting adoption of ICG in pediatric surgical oncology. Further international collaborations are needed to study the applications and limitations of ICG in pediatric surgical oncology.

Feasibility of indocyanine green-guided localization of pulmonary nodules in children with solid tumors.

BACKGROUND: Clearing all pulmonary metastases is essential for curing pediatric solid tumors. However, intraoperative localization of such pulmonary nodules can be challenging. Therefore, an intraoperative tool that localizes pulmonary metastases is needed to improve diagnostic and therapeutic resections. Indocyanine green (ICG) real-time fluorescence imaging is used for this purpose in adult solid tumors, but its utility in pediatric solid tumors has not been determined. METHODS: A single-center, open-label, nonrandomized, prospective clinical trial (NCT04084067) was conducted to assess the ability of ICG to localize pulmonary metastases of pediatric solid tumors. Patients with pulmonary lesions who required resection, either for therapeutic or diagnostic intent, were included. Patients received a 15-minute intravenous infusion of ICG (1.5 mg/kg), and pulmonary metastasectomy was performed the following day. A near-infrared spectroscopy iridium system was optimized to detect ICG, and all procedures were photo-documented and recorded. RESULTS: ICG-guided pulmonary metastasectomies were performed in 12 patients (median age: 10.5 years). A total of 79 nodules were visualized, 13 of which were not detected by preoperative imaging. Histologic examination confirmed the following histologies: hepatoblastoma (n = 3), osteosarcoma (n = 2), and one each of rhabdomyosarcoma, Ewing sarcoma, inflammatory myofibroblastic tumor, atypical cartilaginous tumor, neuroblastoma, adrenocortical carcinoma, and papillary thyroid carcinoma. ICG guidance failed to localize pulmonary metastases in five (42%) patients who had inflammatory myofibroblastic tumor, atypical cartilaginous tumor, neuroblastoma, adrenocortical carcinoma, or papillary thyroid carcinoma. CONCLUSIONS: ICG-guided identification of pulmonary nodules is not feasible for all pediatric solid tumors. However, it may localize most metastatic hepatic tumors and high-grade sarcomas in children.

A Novel Standard for Systematic Reporting of Neuroblastoma Surgery: The International Neuroblastoma Surgical Report Form (INSRF): A Joint Initiative by the Pediatric Oncological Cooperative Groups SIOPEN∗, COG∗∗, and GPOH∗∗∗.

OBJECTIVE: To create the first structured surgical report form for NBL with international consensus, to permit standardized documentation of all NBL-related surgical procedures and their outcomes. SUMMARY OF BACKGROUND DATA: NBL, the most common extracranial solid malignant tumor in children, covers a wide spectrum of tumors with significant differences in anatomical localization, organ or vessel involvement, and tumor biology. Complete surgical resection of the primary tumor is an important part of NBL treatment, but maybe hazardous, prone to complications and its role in high-risk disease remains debated. Various surgical guidelines exist within the protocols of the different cooperative groups, although there is no standardized operative report form to document the surgical treatment of NBL. METHODS: After analyzing the treatment protocols of the SIOP Europe International Neuroblastoma Study Group, Children's Oncology Group, and Gesellschaft fuer Paediatrische Onkologie und Haematologie - German Association of Pediatric Oncology and Haematology pediatric cooperative groups, important variables were defined to completely describe surgical biopsy and resection of NBL and their outcomes. All variables were discussed within the Surgical Committees of SIOP Europe International Neuroblastoma Study Group, Children's Oncology Group, and Gesellschaft fuer Paediatrische Onkologie und Haematologie - German Association of Pediatric Oncology and Haematology. Thereafter, joint meetings were organized to obtain intercontinental consensus. RESULTS: The "International Neuroblastoma Surgical Report Form" provides a structured reporting tool for all NBL surgery, in every anatomical region, documenting all Image Defined Risk Factors and structures involved, with obligatory reporting of intraoperative and 30 day-postoperative complications. CONCLUSION: The International Neuroblastoma Surgical Report Form is the first universal form for the structured and uniform reporting of NBL-related surgical procedures and their outcomes, aiming to facilitate the postoperative communication, treatment planning and analysis of surgical treatment of NBL.

Robotic Surgery in Pediatric Oncology: Lessons Learned from the First 100 Tumors-A Nationwide Experience.

BACKGROUND: While robotics has become commonplace in adult oncology, it remains rare in pediatric oncology due to the rarity of childhood cancers. We present the results of a large nationwide experience with robotic oncology, with the aim of providing practical and feasible guidelines for child selection. METHODS: This was a prospective analysis performed over a period of 4 years. Treatment was delivered according to the Société Internationale d'Oncologie Pédiatrique/International Society of Paediatric Oncology Europe Neuroblastoma Group (SIOP/SIOPEN) protocols. Indications were approved by a certified tumor board. RESULTS: Overall, 100 tumors were resected during 93 procedures (abdomen, 67%; thorax, 17%; pelvis, 10%; retroperitoneum, 6%) in 89 children (56 girls). The median age at surgery was 8.2 years (range 3.6-13); 19 children (21%) harbored germinal genetic alterations predisposing to cancer. No intraoperative tumor ruptures occurred. Seven conversions (8%) to an open approach were performed. Neuroblastic tumors (n = 31) comprised the main group (18 neuroblastomas, 4 ganglioneuroblastomas, 9 ganglioneuromas) and renal tumors comprised the second largest group (n = 24, including 20 Wilms' tumors). The remaining 45 tumors included neuroendocrine (n = 12), adrenal (n = 9), germ-cell (n = 7), pancreatic (n = 4), thymic (n = 4), inflammatory myofibroblastic (n = 4), and different rare tumors (n = 5). Overall, 51 tumors were malignant, 2 were borderline, and 47 were benign. The median hospital stay was 3 days (2-4), and five postoperative complications occurred within the first 30 days. During a median follow-up of 2.4 years, one child (Wilms' tumor) presented with pleural recurrence. One girl with Wilms' tumor died of central nervous system metastasis. CONCLUSIONS: Robotic surgery for pediatric tumors is a safe option in highly selected cases. Indications should be discussed by tumor boards to avoid widespread and uncontrolled application.

Long-term urological complications after conservative local treatment (surgery and brachytherapy) in children with bladder-prostate rhabdomyosarcoma: A single-team experience.

BACKGROUND: Outcome of children with bladder-prostate rhabdomyosarcoma (RMS) has improved with multimodal therapies, including surgery and/or radiotherapy for local treatment. Our aim was to report long-term urological complications after a conservative approach combining conservative surgery and brachytherapy. PATIENTS AND METHODS: Eighty-six patients, free of disease, were retrospectively reviewed. Symptoms related to urinary tract obstruction, incontinence, infection, and lithiasis were reported and graded according to the Common Terminology Criteria for Adverse Events (CTCAE) classification. Only symptomatic patients underwent urodynamic studies. Risk factors for complications were analyzed. RESULTS: There were 76 males and 10 females. The median follow-up was 6.3 years (18 months to 24 years). Complications occurred after a median follow-up of 5 years (0-21). Twenty-two patients (26%) had long-term urological complications. Urinary tract obstruction was found in 15 patients (17%) and urinary incontinence in 14 patients (16%). Recurrent urinary tract infection occurred in four patients and urinary lithiasis in four (5%). The underlying physiopathology included bladder dysfunction in 15 patients (17%), urethral stenosis in six (7%), and ureterovesical junction stenosis in five (6%). On univariate analysis, posterior bladder wall dissection (p = .001), bladder neck trigone dissection (p = .010), and partial prostatectomy (p = .023) were significantly associated with an increased risk of bladder dysfunction; on multivariate analysis, only age ≤2 years (p = .028) at operation and posterior bladder wall dissection (p = .006) were found to be significant. CONCLUSION: The conservative surgical approach combined with brachytherapy for bladder-prostate RMS leads to long-term urological complications in 26% of survivors. Optimizing brachytherapy doses for young children and establishing a clear and long-term follow-up protocol could help to reduce these complications.

Mowat Wilson syndrome and Hirschsprung disease: a retrospective study on functional outcomes.

AIM OF THE STUDY: Mowat Wilson syndrome (MWS) is a complex genetic disorder due to mutation or deletion of the ZEB2 gene (ZFHX1B), including multiple clinical features. Hirschsprung disease is associated with this syndrome with a prevalence between 43 and 57%. The aim of this study was to demonstrate the severe outcomes and the high complication rates in children with MWS, focusing on their complicated follow-up. METHODS: A retrospective comparative study was conducted on patients referred to Robert-Debré Children's Hospital for MWS from 2003 to 2018. Multidisciplinary follow-up was carried out by surgeons, geneticists, gastroenterologists, and neurologists. Data regarding patient characteristics, surgical management, postoperative complications, and functional outcomes were collected. RESULTS: Over this period of 15 years, 23 patients were diagnosed with MWS. Hirschsprung disease was associated with 10 of them (43%). Of these cases, two patients had recto-sigmoïd aganglionosis (20%), three had aganglionic segment extension to the left colic angle (30%), two to the right colic angle (20%), and three to the whole colon (30%). The median follow-up was 8.5 years (2 months-15 years). All patients had seizures and intellectual disability. Six children (60%) presented with cardiac defects. At the last follow-up, three patients still had a stoma diversion and 7 (70%) were fed orally. One patient died during the first months. Eight (80%) of these children required a second surgery due to complications. At the last follow-up, three patients reported episodes of abdominal bloating (42%), one recurrent treated constipation (14.3%), and one soiling (14.3%). Genetic analysis identified three patients with heterozygous deletions, three with codon mutations, and three with frameshift mutations. CONCLUSIONS: MWS associated with Hirschsprung disease has a high rate of immediate surgical complications but some patients may achieve bowel function comparable with non-syndromic HD patients. A multidisciplinary follow-up is required for these patients. LEVEL OF EVIDENCE: Retrospective observational single cohort study, Level 3.

Robotic-assisted laparoscopic management of renal tumors in children: Preliminary results.

AIM: We present the preliminary results of robotic-assisted laparoscopic (RAL) total and partial nephrectomy for renal malignant tumors in children. METHODS: This is a prospective study of patients operated with RAL between December 2016 and September 2018. Patients with Wilms tumors were treated according to the SIOP-2001 protocol. Patient and tumor characteristics, type of surgery, surgical-related morbidity, and oncologic outcomes were recorded. Results were compared with a series of patients with similar age- and tumor-related characteristics operated during the same period by an open surgical approach. RESULTS: Ten children underwent RAL nephrectomy with a mean age of five years (3.2-14.1 years). Total nephrectomy was done in six cases for Wilms tumor and in one case for renal sarcoma; three cases were converted. Complete removal of tumor without rupture was achieved in all cases. Postoperative course was uneventful, and patients were discharged between days 2 and 7. Neither recurrence nor medium-term complications occurred. Nine patients are alive with a median follow-up of 16 months (6-27 months) and one female died from complications of central nervous system metastases one year after surgery. When compared with the open surgical approach group, median tumor volume was smaller (P = 0.005), hospital stay was shorter (P = 0.01), and operative time was similar (P = 0.20). CONCLUSIONS: RAL total and partial nephrectomy procedure for renal tumor in children may be an option in carefully selected cases. Indication should be discussed at tumor boards and surgery performed while adhering strictly to oncological surgical rules.

Multidisciplinary surgical strategy for dumbbell neuroblastoma: A single-center experience of 32 cases.

INTRODUCTION: Prognosis of dumbbell neuroblastoma (NBL) is mainly determined by the sequelae induced by the tumor itself and the neurosurgical approach. However, after primary chemotherapy, surgical management of the residual tumor, especially the spinal canal component, remains controversial. METHODS: We conducted a single-center retrospective cohort study over the last 15 years (2002-2017) including patients treated for NBL with spinal canal extension focusing on timing and type of surgery, complications, and functional and oncological follow-up. RESULTS: Thirty-two children (14 M, 18 F) were managed for NBL, with the majority (26) presenting with NBL stroma poor while four had ganglioneuroblastoma intermixed, one nodular, and one ganglioneuroma. All but two patients received neoadjuvant chemotherapy. Upfront laminotomy for spinal cord decompression was performed in two patients; nine patients had extraspinal surgery with a follow-up neurosurgical procedure in seven cases; eight patients had initial neurosurgery followed by an extraspinal procedure, while six patients underwent a combined multidisciplinary approach. With a median follow up of 3.6 years (0.1-14.9), 29 patients (90.6) are alive and two out of three (19, 65.5%) have functional sequelae. CONCLUSION: Patients with NBL with persistent spinal canal extension of the tumor after neoadjuvant chemotherapy treated at our center had outcomes that compare favorably with the literature. This is likely due to the multidisciplinary approach to optimal surgical strategy and continuous evaluation of the respective risks of tumor progression. Neurological disability results from initial spinal cord compression or the radicular sacrifice required for tumor resection.