Intraoperative adverse events among surgeons in Singapore: a multicentre cross-sectional study on impact and support

BACKGROUND

It is known that many surgeons encounter intraoperative adverse events which can result in Second Victim Syndrome (SVS), with significant detriment to their emotional and physical health. There is, however, a paucity of Asian studies in this space. The present study thus aimed to explore the degree to which the experience of an adverse event is common among surgeons in Singapore, as well as its impact, and factors affecting their responses and perceived support systems.

METHODS

A self-administered survey was sent to surgeons at four large tertiary hospitals. The 42-item questionnaire used a systematic closed and open approach, to assess: Personal experience with intraoperative adverse events, emotional, psychological and physical impact of these events and perceived support systems.

RESULTS

The response rate was 57.5% (n = 196). Most respondents were male (54.8%), between 35 and 44 years old, and holding the senior consultant position. In the past 12 months alone, 68.9% recalled an adverse event. The emotional impact was significant, including sadness (63.1%), guilt (53.1%) and anxiety (45.4%). Speaking to colleagues was the most helpful support source (66.7%) and almost all surgeons did not receive counselling (93.3%), with the majority deeming it unnecessary (72.2%). Notably, 68.1% of the surgeons had positive takeaways, gaining new insight and improving vigilance towards errors. Both gender and surgeon experience did not affect the likelihood of errors and emotional impact, but more experienced surgeons were less likely to have positive takeaways (p = 0.035). Individuals may become advocates for patient safety, while simultaneously championing the cause of psychological support for others.

CONCLUSIONS

Intraoperative adverse events are prevalent and its emotional impact is significant, regardless of the surgeon's experience or gender. While colleagues and peer discussions are a pillar of support, healthcare institutions should do more to address the impact and ensuing consequences.

BRD4 isoforms have distinct roles in tumour progression and metastasis in rhabdomyosarcoma

BRD4, a bromodomain and extraterminal (BET) protein, is deregulated in multiple cancers and has emerged as a promising drug target. However, the function of the two main BRD4 isoforms (BRD4-L and BRD4-S) has not been analysed in parallel in most cancers. This complicates determining therapeutic efficacy of pan-BET inhibitors. In this study, using functional and transcriptomic analysis, we show that BRD-L and BRD4-S isoforms play distinct roles in fusion negative embryonal rhabdomyosarcoma. BRD4-L has an oncogenic role and inhibits myogenic differentiation, at least in part, by activating myostatin expression. Depletion of BRD4-L in vivo impairs tumour progression but does not impact metastasis. On the other hand, depletion of BRD4-S has no significant impact on tumour growth, but strikingly promotes metastasis in vivo. Interestingly, BRD4-S loss results in the enrichment of BRD4-L and RNA Polymerase II at integrin gene promoters resulting in their activation. In fusion positive alveolar rhabdomyosarcoma, BRD4-L is unrestricted in its oncogenic role, with no evident involvement of BRD4-S. Our work unveils isoform-specific functions of BRD4 in rhabdomyosarcoma.

Targeted Degradation of XIAP is Sufficient and Specific to Induce Apoptosis in MYCN-overexpressing High-risk Neuroblastoma

XIAP, the most potent mammalian inhibitor of apoptosis protein (IAP), critically restricts developmental culling of sympathetic neuronal progenitors, and is correspondingly overexpressed in most MYCN-amplified neuroblastoma tumors. Because apoptosis-related protein in the TGFβ signaling pathway (ARTS) is the only XIAP antagonist that directly binds and degrades XIAP, we evaluated the preclinical effectiveness and tolerability of XIAP antagonism as a novel targeting strategy for neuroblastoma. We found that antagonism of XIAP, but not other IAPs, triggered apoptotic death in neuroblastoma cells. XIAP silencing induced apoptosis while overexpression conferred protection from drug-induced apoptosis. From a screen of IAP inhibitors, first-in-class ARTS mimetic A4 was most effective against high-risk and high XIAP-expressing neuroblastoma cells, and least toxic toward normal liver- and bone marrow-derived cells, compared with pan-IAP antagonists. On target engagement assays and nuclear magnetic resonance spectroscopy, A4 was observed to degrade rather than inhibit XIAP, catalyzing rapid degradation of XIAP through the ubiquitin-proteasome pathway. In MYCN-amplified neuroblastoma patient-derived xenografts, A4 significantly prolonged survival as a single agent, and demonstrated synergism with standard-of-care agents to reduce their effective required doses 3- to 6-fold. Engagement and degradation of XIAP by ARTS mimetics is a novel targeting strategy for neuroblastoma that may be especially effective against MYCN-amplified disease with intrinsically high XIAP expression. First-in-class ARTS mimetic A4 demonstrates preclinical efficacy and warrants further development and study.

SIGNIFICANCE

XIAP degradation is sufficient to kill MYCN-amplified neuroblastoma which overexpresses and relies on XIAP as a brake against cell death, without affecting normal cells.

Exploiting frequent and specific expression of PRL3 in pediatric solid tumors for first-in-child use of PRL3-zumab humanized antibody

Phosphatase of regenerating liver 3 (PRL3) is a specific tumor antigen overexpressed in a broad range of adult cancer types. However, its physiological expression in pediatric embryonal and mesenchymal tumors and its association with clinical outcomes in children is unknown. We sought to profile the expression of PRL3 in pediatric tumors in relation to survival outcomes, expression of angiogenesis markers, and G-protein-coupled receptor (GPCR)-mitogen-activated protein kinase (MAPK) signaling targets. PRL3-zumab, a first-in-class humanized antibody, was administered in a dose escalation schedule in a first-in-child clinical trial to study toxicity, pharmacokinetics, and clinical outcomes. Among 64 pediatric tumors, PRL3 was most frequently expressed in neuroblastoma (100%), rhabdomyosarcoma and non-rhabdomyosarcoma soft tissue sarcomas (71%), and renal sarcomas (60%) but absent in paired normal tissues. PRL3 was expressed in 75% of relapsed tumors and associated with shorter median event-free survival. Microarray profiling of PRL3-positive tumors showed elevation of angiogenin, TIMP1 and TIMP2, and GPCR-MAPK signaling proteins that commonly interacted with PRL3. The first use of PRL3-zumab in a pediatric patient saw no adverse events. A 28.6% reduction in maximum target lesion diameter was achieved when PRL3-zumab was administered concurrently with hypofractionated radiation. These findings support wider exploration of PRL3 expression in embryonal and mesenchymal tumors and further clinical application of PRL3-zumab in pediatric patients.

Solitary pulmonary nodule in an early adolescent

An early adolescent boy presented with 1-week history of left-sided chest pain, localised to the anterior aspect of seventh intercostal space. A chest radiograph revealed a round opacity measuring 2.6×2.4 cm in the left mid zone. A CT scan of the chest confirmed a solitary well-circumscribed pulmonary nodule measuring 2.7×2.4 cm in the central left upper lobe, adjacent to the anterior segmental bronchus. Positron emission tomography scan showed mild to moderate fluorodeoxyglucose uptake (maximum standardized uptake value 5.2) in the nodule. He underwent a video-assisted left upper lobectomy. Histology of the nodule was consistent with sclerosing pneumocytoma, a rare benign lung neoplasm that occurs predominantly in middle-aged women of Asian descent. This case highlights the challenges in diagnosis and management of solitary pulmonary nodules in children, especially those who remain symptomatic or only have minimal symptoms and provides a pragmatic approach to this condition.

BRD4 isoforms have distinct roles in tumor progression and metastasis in embryonal rhabdomyosarcoma

BRD4, a bromodomain and extraterminal (BET) protein, is deregulated in multiple cancers and has emerged as a promising drug target. However, the function of the two main BRD4 isoforms (BRD4-L and BRD4-S) has not been analyzed in parallel in most cancers. This complicates determining therapeutic efficacy of pan-BET inhibitors. In this study, using functional and transcriptomic analysis, we show that BRD-L and BRD4-S isoforms play distinct roles in embryonal rhabdomyosarcoma. BRD4-L has an oncogenic role and inhibits myogenic differentiation, at least in part, by activating myostatin expression. Depletion of BRD4-L in vivo impairs tumor progression but does not impact metastasis. On the other hand, depletion of BRD4-S has no significant impact on tumor growth, but strikingly promotes metastasis in vivo . Interestingly, BRD4-S loss results in the enrichment of BRD4-L and RNA Polymerase II at integrin gene promoters resulting in their activation. Our work unveils isoform-specific functions of BRD4 and demonstrates that BRD4-S functions as a gatekeeper to constrain the full oncogenic potential of BRD4-L.

Nephron sparing surgery and surgical management of intravascular extension of Wilms tumor

Although general treatment approaches for Wilms tumor differ between Children's Oncology Group and Société Internationale d'Oncologie Pédiatrique-Renal Tumors Study Group protocols, complex tumors that may be candidates for nephron sparing surgery (NSS) and those with intravascular tumor extension represent a management challenge. In both of these scenarios, anatomic considerations are important in guiding management, making these areas of significant similarities in management between the international groups. This paper aims to explore the current approaches to NSS and intravascular tumor extension by both international groups, with attention to the evidence supporting these approaches and current knowledge gaps.

Generation and multi-dimensional profiling of a childhood cancer cell line atlas defines new therapeutic opportunities

Pediatric solid and central nervous system tumors are the leading cause of cancer-related death among children. Identifying new targeted therapies necessitates the use of pediatric cancer models that faithfully recapitulate the patient's disease. However, the generation and characterization of pediatric cancer models has significantly lagged behind adult cancers, underscoring the urgent need to develop pediatric-focused cell line resources. Herein, we establish a single-site collection of 261 cell lines, including 224 pediatric cell lines representing 18 distinct extracranial and brain childhood tumor types. We subjected 182 cell lines to multi-omics analyses (DNA sequencing, RNA sequencing, DNA methylation), and in parallel performed pharmacological and genetic CRISPR-Cas9 loss-of-function screens to identify pediatric-specific treatment opportunities and biomarkers. Our work provides insight into specific pathway vulnerabilities in molecularly defined pediatric tumor classes and uncovers biomarker-linked therapeutic opportunities of clinical relevance. Cell line data and resources are provided in an open access portal.

Targeting RNA Polymerase I Transcription Activity in Osteosarcoma: Pre-Clinical Molecular and Animal Treatment Studies

The survival rate of patients with osteosarcoma (OS) has not improved over the last 30 years. Mutations in the genes TP53, RB1 and c-Myc frequently occur in OS and enhance RNA Polymerase I (Pol I) activity, thus supporting uncontrolled cancer cell proliferation. We therefore hypothesised that Pol I inhibition may be an effective therapeutic strategy for this aggressive cancer. The Pol I inhibitor CX-5461 has demonstrated therapeutic efficacy in different cancers in pre-clinical and phase I clinical trials; thus, the effects were determined on ten human OS cell lines. Following characterisation using genome profiling and Western blotting, RNA Pol I activity, cell proliferation and cell cycle progression were evaluated in vitro, and the growth of TP53 wild-type and mutant tumours was measured in a murine allograft model and in two human xenograft OS models. CX-5461 treatment resulted in reduced ribosomal DNA (rDNA) transcription and Growth 2 (G2)-phase cell cycle arrest in all OS cell lines. Additionally, tumour growth in all allograft and xenograft OS models was effectively suppressed without apparent toxicity. Our study demonstrates the efficacy of Pol I inhibition against OS with varying genetic alterations. This study provides pre-clinical evidence to support this novel therapeutic approach in OS.

Targeting Mutant Dicer Tumorigenesis in Pleuropulmonary Blastoma via Inhibition of RNA Polymerase I

DICER1 mutations predispose to increased risk for various cancers, particularly pleuropulmonary blastoma (PPB), the commonest lung malignancy of childhood. There is a paucity of directly actionable molecular targets as these tumors are driven by loss-of-function mutations of DICER1. Therapeutic development for PPB is further limited by a lack of biologically and physiologically-representative disease models. Given recent evidence of Dicer's role as a haploinsufficient tumor suppressor regulating RNA polymerase I (Pol I), Pol I inhibition could abrogate mutant Dicer-mediated accumulation of stalled polymerases to trigger apoptosis. Hence, we developed a novel sub-pleural orthotopic PPB patient-derived xenograft (PDX) model that retained both RNase IIIa and IIIb hotspot mutations and recapitulated the cardiorespiratory physiology of intra-thoracic disease, and with it evaluated the tolerability and efficacy of first-in-class Pol I inhibitor CX-5461. In PDX tumors, CX-5461 significantly reduced H3K9 di-methylation and increased nuclear p53 expression, within 24 hours' exposure. Following treatment at the maximum tolerated dosing regimen (12 doses, 30mg/kg), tumors were smaller and less hemorrhagic than controls, with significantly decreased cellular proliferation, and increased apoptosis. As demonstrated in a novel intra-thoracic tumor model of PPB, Pol I inhibition with CX-5461 could be a tolerable and clinically-feasible therapeutic strategy for mutant Dicer tumors, inducing anti-tumor effects by decreasing H3K9 methylation and enhancing p53-mediated apoptosis.

Histone variant H3.3 promotes metastasis in alveolar rhabdomyosarcoma

The relatively quiet mutational landscape of rhabdomyosarcoma (RMS) suggests that epigenetic deregulation could be central to oncogenesis and tumour aggressiveness. Histone variants have long been recognised as important epigenetic regulators of gene expression. However, the role of histone variants in RMS has not been studied hitherto. In this study, we show that histone variant H3.3 is overexpressed in alveolar RMS (ARMS), an aggressive subtype of RMS. Functionally, knockdown of H3F3A, which encodes for H3.3, significantly impairs the ability of ARMS cells to undertake migration and invasion and reduces Rho activation. In addition, a striking reduction in metastatic tumour burden and improved survival is apparent in vivo. Using RNA-sequencing and ChIP-sequencing analyses, we identified melanoma cell adhesion molecule (MCAM/CD146) as a direct downstream target of H3.3. Loss of H3.3 resulted in a reduction in the presence of active marks and an increase in the occupancy of H1 at the MCAM promoter. Cell migration and invasion were rescued in H3F3A-depleted cells through MCAM overexpression. Moreover, we identified G9a, a lysine methyltransferase encoded by EHMT2, as an upstream regulator of H3F3A. Therefore, this study identifies a novel H3.3 dependent axis involved in ARMS metastasis. These findings establish the potential of MCAM as a therapeutic target for high-risk ARMS patients. © 2022 The Pathological Society of Great Britain and Ireland.

Notch-dependent cooperativity between myeloid lineages promotes Langerhans cell histiocytosis pathology

Langerhans cell histiocytosis (LCH) is a potentially fatal neoplasm characterized by the aberrant differentiation of mononuclear phagocytes, driven by mitogen-activated protein kinase (MAPK) pathway activation. LCH cells may trigger destructive pathology yet remain in a precarious state finely balanced between apoptosis and survival, supported by a unique inflammatory milieu. The interactions that maintain this state are not well known and may offer targets for intervention. Here, we used single-cell RNA-seq and protein analysis to dissect LCH lesions, assessing LCH cell heterogeneity and comparing LCH cells with normal mononuclear phagocytes within lesions. We found LCH discriminatory signatures pointing to senescence and escape from tumor immune surveillance. We also uncovered two major lineages of LCH with DC2- and DC3/monocyte-like phenotypes and validated them in multiple pathological tissue sites by high-content imaging. Receptor-ligand analyses and lineage tracing in vitro revealed Notch-dependent cooperativity between DC2 and DC3/monocyte lineages during expression of the pathognomonic LCH program. Our results present a convergent dual origin model of LCH with MAPK pathway activation occurring before fate commitment to DC2 and DC3/monocyte lineages and Notch-dependent cooperativity between lineages driving the development of LCH cells.

MODL-17. The Childhood Brain Cancer Cell Line Atlas: A Resource for Biomarker Identification and Therapeutic Development

Cell lines represent the most versatile and widely used models of cancer and, as such, are critical for identifying and advancing new therapies. Strikingly, there is a significant gap in both the number of childhood brain cancer cell lines and their characterisation compared to their adult counterparts. To address this inequity, we established a childhood brain cancer cell line atlas (publicly available at vicpcc.org.au/dashboard) encompassing over 180 childhood CNS-derived cell lines, representing 20 tumour types and 11 molecular subtypes. Cell lines are characterized by whole genome, RNA-sequencing, phospho- and total proteomics, DNA methylation and ATAC-seq analyses. Multi-omic factor analysis revealed distinct lineage-specified classification of our cell line cohort. In parallel, high throughput drug and CRISPR/Cas9 screens were conducted to map the functional dependencies in over 70 childhood CNS cell lines, including 47 paediatric high grade glioma models. These screens identified both lineage and molecular-subtype specific genetic and drug dependencies, underscoring the utility of this wide-scale approach. Machine based learning approaches to predict genotype-phenotype correlations uncovered distinct paediatric-specific biomarkers of growth dependency, highlighting the unique genetic wiring underlying paediatric CNS tumours. Finally, by integrating functional, molecular and drug profiles of paediatric CNS cell lines, we construct a system to prioritize investigation of novel therapeutic target-biomarkers pairs in specific CNS tumour types.

Mitochondrial calcium uptake regulates tumour progression in embryonal rhabdomyosarcoma

Embryonal rhabdomyosarcoma (ERMS) is characterised by a failure of cells to complete skeletal muscle differentiation. Although ERMS cells are vulnerable to oxidative stress, the relevance of mitochondrial calcium homoeostasis in oncogenesis is unclear. Here, we show that ERMS cell lines as well as primary tumours exhibit elevated expression of the mitochondrial calcium uniporter (MCU). MCU knockdown resulted in impaired mitochondrial calcium uptake and a reduction in mitochondrial reactive oxygen species (mROS) levels. Phenotypically, MCU knockdown cells exhibited reduced cellular proliferation and motility, with an increased propensity to differentiate in vitro and in vivo. RNA-sequencing of MCU knockdown cells revealed a significant reduction in genes involved in TGFβ signalling that play prominent roles in oncogenesis and inhibition of myogenic differentiation. Interestingly, modulation of mROS production impacted TGFβ signalling. Our study elucidates mechanisms by which mitochondrial calcium dysregulation promotes tumour progression and suggests that targeting the MCU complex to restore mitochondrial calcium homoeostasis could be a therapeutic avenue in ERMS.

Impact of treatment refusal and abandonment on survival outcomes in pediatric osteosarcoma in Southeast Asia: A multicenter study

BACKGROUND

Treatment refusal and abandonment (TxRA) are major barriers to improving outcomes among children with sarcomas of the extremities as curative treatment options bearing on amputation or disfiguring surgery, particularly in countries with limited resources. A multi-institutional retrospective study was conducted to determine the predictive factors for TxRA among patients with osteosarcoma associated with survival outcomes across Southeast Asia (SEA).

METHODS

Pediatric patients with osteosarcoma treated between January 1998 and December 2017 in four SEA pediatric oncology centers from three countries were studied. Nelson-Aalen estimates, Kaplan-Meier method, and Cox's proportion hazard model were applied to address the cumulative incidence, survival outcomes, and to identify prognostic factors associated with TxRA.

RESULTS

From a total of 208 patients with osteosarcoma enrolled; 18 (8.7%) patients refused and 41 (19.7%) patients abandoned treatment. Income classification of countries, age at diagnosis, tumor size, disease extent, chemotherapy protocols, and types of surgery were associated with TxRA. Tumor size more than 15 cm was an independent risk factor associated with TxRA. The 5-year overall and relapse-free survivals were 49.4% and 50.4%, respectively. However, these rates declined further to 37.9% and 35.8%, respectively, when TxRA were considered as events. Tumor size larger than 15 cm and metastatic disease were independent risk factors associated with TxRA-sensitive outcomes.

CONCLUSION

The prevalence of TxRA was high in SEA, particularly in lower middle-income countries. Factors associated with TxRA related to tumor burden. Treatment outcomes could be substantially improved by lowering the refusal and abandonment rates.

Predictors and Treatment Outcomes of Pediatric Osteosarcoma in Diverse Socioeconomic Backgrounds in Southeast Asia: A Retrospective Multicenter Study

Background:

Pediatric osteosarcoma outcomes among developed and developing countries have not been previously compared. Countries in Southeast Asia (SEA) have a wide variety of socioeconomic statuses. A multi-institutional retrospective study was conducted to determine the prognostic factors and outcomes for pediatric osteosarcoma in SEA.

Methods:

Pediatric patients with osteosarcoma treated between 1998 and 2017 in 4 SEA pediatric oncology centers were studied. Countries were classified using the World Bank Atlas method. Kaplan–Meier method and Cox’s Proportion Hazard Model were applied to estimate survival outcomes and identify prognostic factors.

Results:

In all, 149 patients with osteosarcoma with a mean age of 12.48±3.66 years were enrolled. The localized to metastatic disease ratio was 1.5:1. The 5-year overall survival (OS) and event-free survival (EFS) were 53.8% and 42%, respectively. Prognostic factors associated with outcomes were country, stage of disease, MTX-containing regimens, and surgery type (p-value <0.05). In patients with localized disease, EFS was superior with limb-salvage surgery (62%) than amputation or rotationplasty (40%) (p-value 0.009). MTX-containing chemotherapies provided higher OS (45.3%) and EFS (37.9%) than non-MTX regimens (12.3% and 10.7%, respectively) among metastatic patients (p-value 0.004 and 0.005, respectively). Metastatic disease was an independent prognostic factor for death but not relapse outcome.

Conclusion:

The disease outcomes in SEA were acceptable compared to developed countries. The stage of disease was the only independent prognostic factor. MTX-containing regimens and limb-salvage surgery should be considered where possible.

Association of anesthetic and surgical risk factors with outcomes of initial diagnostic biopsies in a current cohort of children with anterior mediastinal masses

Background

Diagnostic biopsies of pediatric anterior mediastinal masses (AMMs) are high-risk procedures in which general anesthesia (GA) is traditionally avoided. However, awareness of historically recognized risk factors and corresponding perioperative management have improved over time and may now no longer strictly preclude the use of GA. Therefore, in this study, we examined the association of anesthetic and surgical risk factors and modalities with resulting procedural and survival outcomes in a current patient cohort.

Methods

We retrospectively reviewed charts of 35 children with AMMs who underwent initial diagnostic biopsies between January 2001 and August 2019, and determined tracheal compression and deviation from archival CT scans and procedural and disease outcomes.

Results

Twenty-three (65%) patients underwent GA while 12 (35%) received sedation. Among patients with available CT measurements, 13 of 25 (52%) had >50% anteroposterior tracheal diameter reduction. Patients with >50% anteroposterior tracheal compression received sedation more frequently (p=0.047) and were positioned upright (p=0.015) compared with patients with ≤50% compression, although 4 of 13 and 9 of 12, respectively, still received GA. Intraoperative adverse events (AEs) occurred in four (11.4%) patients: three received GA, and all were positioned supine or lateral. AEs were not associated with radiographic airway risk factors but were significantly associated with morphine and sevoflurane use (p<0.001) and with thoracoscopic biopsies (p=0.035). There were no on-table mortalities, but four delayed deaths occurred (three related to disease and one from late procedural complications).

Conclusions

In a current cohort of pediatric AMM biopsies, patients with >50% anteroposterior tracheal compression were more frequently managed with a conservative perioperative management strategy, though not completely excluding GA. The corresponding reduction in frequency of procedural AEs in this traditionally high-risk group suggests that increased awareness of procedural risk factors and appropriate risk-guided perioperative management choices may obviate the procedural mortality historically associated with pediatric AMM biopsies.

Ectopic CD137 expression by rhabdomyosarcoma provides selection advantages but allows immunotherapeutic targeting

Rhabdomyosarcoma (RMS) is a heterogeneous soft tissue neoplasm most frequently found in children and adolescents. As the prognosis for recurrent and metastatic RMS remains poor, immunotherapies are hoped to improve quality of life and survival. CD137 is a member of tumor necrosis factor receptor family and a T cell costimulatory molecule which induces potent cellular immune responses that are able to eliminate malignant cells. Therefore, it was puzzling to find expression of CD137 on an RMS tissue microarray by multiplex staining. CD137 is not only expressed by infiltrating T cells but also by malignant RMS cells. Functional in vitro experiments demonstrate that CD137 on RMS cells is being transferred to adjacent antigen-presenting cells by trogocytosis, where it downregulates CD137 ligand, and thereby reduces T cell costimulation which results in reduced killing of RMS cells. The transfer of CD137 and the subsequent downregulation of CD137 ligand is a physiological negative feedback mechanism that is likely usurped by RMS, and may facilitate its escape from immune surveillance. In addition, CD137 signals into RMS cells and induces IL-6 and IL-8 secretion, which are linked to RMS metastasis and poor prognosis. However, the ectopic expression of CD137 on RMS cells is an Achilles’ heel that may be utilized for immunotherapy. Natural killer cells expressing an anti-CD137 chimeric antigen receptor specifically kill CD137-expressing RMS cells. Our study implicates ectopic CD137 expression as a pathogenesis mechanism in RMS, and it demonstrates that CD137 may be a novel target for immunotherapy of RMS.

Anaesthetic modality and post-surgical oncological outcomes for paediatric tumours: is there a link?

INTRODUCTION

Children with solid organ tumours often present for curative surgery. Even with the best surgical technique, micrometastases can occur. Preclinical studies support the postulation that neuraxial anaesthesia maintains the body's immune and inflammatory milieu against metastasis. However, human retrospective adult studies showed varying results, and no study has been done in children. We aimed to find out if intraoperative epidural, perioperative opioid and volatile dose are associated with relapse-free survival (RFS) in children with solid organ tumours.

METHODS

This is a retrospective cohort study of 126 children from a tertiary paediatric unit who were diagnosed with solid organ tumours (neuroblastoma, hepatoblastoma or sarcoma) over a 16-year period. RFS, stratified by tumour subtypes, was estimated using the Kaplan-Meier method. Adjusted hazard ratios (aHRs) were obtained from multivariable Cox regression models after taking potential covariates into account.

RESULTS

Of 126 children with solid organ tumours (51.6% neuroblastoma, 34.9% sarcoma and 13.5% hepatoblastoma), 53.2% received combined general anaesthesia (GA)/epidural. A total of 21 (31.3%) and 20 (33.9%) patients relapsed during the study period in the combined GA/epidural group and the GA alone group, respectively. Patients with sarcoma receiving combined GA/epidural had a clinically meaningful lower risk of relapse compared to patients receiving GA alone (aHR 0.51, 95% confidence interval 0.14-1.79), although this was not statistically significant.

CONCLUSION

Our study demonstrated some clinically meaningful associations, especially in paediatric sarcoma patients. Overall, however, there was no statistically significant association between epidural use and an improved RFS.

Mechanical versus Chemical Pleurodesis after Bullectomy for Primary Spontaneous Pneumothorax: A Systemic Review and Meta-Analysis

INTRODUCTION

 Primary spontaneous pneumothorax (PSP) and its high recurrence rate pose a therapeutic challenge to both patients and their managing surgeons. Mechanical or chemical pleurodesis can be used to prevent recurrence, but the optimal treatment often remains a matter of debate. This meta-analysis aims to compare the outcomes between mechanical and chemical pleurodesis following bullectomy for PSP.

MATERIALS AND METHODS

 Studies published up to 2019 were searched from Medline, Embase, Google Scholar, and Cochrane databases. A meta-analysis of randomized controlled trials (RCTs) and observational cohort studies (OCSs) comparing outcomes between mechanical and chemical pleurodesis for PSP was performed.

RESULTS

 Seven studies (one RCT and six OCSs) were included, comprising 1,032 cases of mechanical (799 abrasions, 202 pleurectomies, and 31 unspecified abrasions/pleurectomies/both), and 901 cases of chemical (643 talc, 69 minocycline, and 189 unspecified talc/kaolin) pleurodesis. The recurrence rate of pneumothorax after chemical pleurodesis (1.2%) was significantly lower than mechanical pleurodesis (4.0%) (pooled odds ratio [OR] = 3.00; 95% confidence interval [CI] = 1.59-5.67; p = 0.0007; I ² = 19%). Hospital stay was also slightly shorter in the chemical pleurodesis group (pooled mean difference [MD] = 0.42 days; 95% CI = 0.12-0.72; p = 0.005; I ² = 0%). There was no statistically significant difference in postoperative complications (pooled OR = 1.18; 95%CI = 0.40-3.48; p = 0.76; I ² = 71%) and operative time (pooled MD = 3.50; 95%CI = -7.28 to 14.28; p = 0.52; I ² = 99%) between these two groups.

CONCLUSION

 Chemical pleurodesis is superior to mechanical pleurodesis following bullectomy for PSP in reducing hospital stay and recurrence rate. However, more RCTs with longer follow-up are necessary to demonstrate the benefit of chemical pleurodesis for PSP.

Congenital mesoblastic nephroma is characterised by kinase mutations including EGFR internal tandem duplications, the ETV6-NTRK3 fusion, and the rare KLHL7-BRAF fusion

AIMS

Congenital mesoblastic nephroma (CMN) is histologically classified into classic, cellular and mixed subtypes. The aims of this study were to characterise the clinical, pathological and molecular features of a series of CMNs, and to determine the utility of pan-Trk and epidermal growth factor receptor (EGFR) immunohistochemistry as surrogate markers for NTRK gene fusions and EGFR internal tandem duplications (ITDs).

METHODS AND RESULTS

Twenty-two archival CMN cases (12 classic, five cellular, and five mixed) were tested for the ETV6-NTRK3 fusion and EGFR ITD transcripts by the use of reverse transcriptase polymerase chain reaction (PCR), and next-generation sequencing-based anchored multiplex PCR. All 12 classic CMNs had EGFR ITD. Of the five cellular CMNs, four had the ETV6-NTRK3 fusion and one had the KLHL7-BRAF fusion. Of the five mixed CMNs, four had EGFR ITD, and one had the ETV6-NTRK3 fusion. Pan-Trk immunoreactivity was 100% sensitive and 94.1% specific for the presence of NTRK rearrangement. However, EGFR staining was only 62.5% sensitive and 33.3% specific for EGFR ITD.

CONCLUSIONS

EGFR ITD is a consistent genetic event in classic CMN. A majority of cellular CMNs have the ETV6-NTRK3 fusion. Rare cellular CMNs may harbour non-canonical mutations such as the KLHL7-BRAF fusion, which was found in one case. Mixed CMNs may have either EGFR ITD or the ETV6-NTRK3 fusion. Pan-Trk immunohistochemistry is a sensitive, albeit not perfectly specific, marker for NTRK rearrangement. EGFR immunohistochemistry is not helpful as a marker of EGFR ITD.

Neuroblastoma patient-derived cultures are enriched for a mesenchymal gene signature and reflect individual drug response

Ex vivo evaluation of personalized models can facilitate individualized treatment selection for patients, and advance the discovery of novel therapeutic options. However, for embryonal malignancies, representative primary cultures have been difficult to establish. We developed patient‐derived cell cultures (PDCs) from chemo‐naïve and post–treatment neuroblastoma tumors in a consistent and efficient manner, and characterized their in vitro growth dynamics, histomorphology, gene expression, and functional chemo‐response. From 34 neuroblastoma tumors, 22 engrafted in vitro to generate 31 individual PDC lines, with higher engraftment seen with metastatic tumors. PDCs displayed characteristic immunohistochemical staining patterns of PHOX2B, TH, and GD2 synthase. Concordance of MYCN amplification, 1p and 11q deletion between PDCs and patient tumors was 83.3%, 72.7%, and 80.0% respectively. PDCs displayed a predominantly mesenchymal‐type gene expression signature and showed upregulation of pro‐angiogenic factors that were similarly enriched in culture medium and paired patient serum samples. When tested with standard‐of‐care cytotoxics at human C_max‐equivalent concentrations, MYCN‐amplified and non‐MYCN‐amplified PDCs showed a differential response to cyclophosphamide and topotecan, which mirrored the corresponding patients’ responses, and correlated with gene signatures of chemosensitivity. In this translational proof‐of‐concept study, early‐phase neuroblastoma PDCs enriched for the mesenchymal cell subpopulation recapitulated the individual molecular and phenotypic profile of patient tumors, and highlighted their potential as a platform for individualized ex vivo drug‐response testing.

Massively parallel single-molecule telomere length measurement with digital real-time PCR

Telomere length is a promising biomarker for age-associated diseases and cancer, but there are still substantial challenges to routine telomere analysis in clinics because of the lack of a simple and rapid yet scalable method for measurement. We developed the single telomere absolute-length rapid (STAR) assay, a novel high-throughput digital real-time PCR approach for rapidly measuring the absolute lengths and quantities of individual telomere molecules. We show that this technique provides the accuracy and sensitivity to uncover associations between telomere length distribution and telomere maintenance mechanisms in cancer cell lines and primary tumors. The results indicate that the STAR assay is a powerful tool to enable the use of telomere length distribution as a biomarker in disease and population-wide studies.

Larotrectinib followed by selitrectinib in a novel DCTN1-NTRK1 fusion undifferentiated pleomorphic sarcoma

INTRODUCTION

Neurotrophic receptor tyrosine kinase fusions cause overexpression or activation of kinase and are believed to confer oncogenic potential in some non-rhabdomyosarcoma soft tissue sarcomas. TRK inhibitors have recently been shown to induce responses in these tumours though current experience with these agents is still limited.

CASE REPORT

We report a case of an adolescent with treatment-refractory non-rhabdomyosarcoma soft tissue sarcomas, carrying a novel DCTN1-NTRK1 gene fusion whose progressive disease was treated with multi-kinase and TRK inhibitors.Management and outcome: Our patient was started on pan-TRK inhibitor larotrectinib, as his disease progressed after chemotherapy, radiation therapy and surgery, based on next-generation sequencing test showing DCTN1-NTRK1 gene fusion. He responded quickly to larotrectinib with the improvement of symptoms and reduction of masses. However, this response was short-lived due to the development of acquired solvent front resistance mutation. This patient did not respond to next-generation TRK inhibitor selitrectinib and eventually succumbed to his disease.

DISCUSSION

The initial rapid and drastic response of our patient to larotrectinib was not sustained due to the development of acquired resistance. This case emphasizes the need for upfront and periodic next-generation sequencing testing to guide treatment of patients with refractory non-rhabdomyosarcoma soft tissue sarcomas.

Destined to Die: Apoptosis and Pediatric Cancers

Apoptosis (programmed cell death) is a systematic and coordinated cellular process that occurs in physiological and pathophysiological conditions. Sidestepping or resisting apoptosis is a distinct characteristic of human cancers including childhood malignancies. This review dissects the apoptosis pathways implicated in pediatric tumors. Understanding these pathways not only unraveled key molecules that may serve as potential targets for drug discovery, but also molecular nodes that integrate with other signaling networks involved in processes such as development. This review presents current knowledge of the complex regulatory system that governs apoptosis with respect to other processes in pediatric cancers, so that fresh insights may be derived regarding treatment resistance or for more effective treatment options.

Primary Adrenal Angiomatoid Fibrous Histiocytoma With Novel EWSR1-ATF1 Gene Fusion Exon-Exon Breakpoint

We describe the clinical, pathological, and molecular features of a primary adrenal angiomatoid fibrous histiocytoma (AFH) in an 11-year-old girl presenting with pyrexia of unknown origin. We performed next-generation sequencing-based anchored multiplex polymerase chain reaction (Archer® FusionPlex® sarcoma assay), which revealed an EWSR1-ATF1 gene fusion with novel breakpoints in exon 11 of EWSR1 and exon 3 of ATF1. The pyrexia resolved fully after surgical resection, and the patient was disease-free on follow-up at 1 year and 6 months. This case exemplifies the value of molecular testing of pediatric neoplasms presenting at unusual sites for diagnosis and identification of novel gene fusion breakpoints.

Retroperitoneal tumors and congenital variations in vascular anatomy of retroperitoneal great vessels

BACKGROUND/OBJECTIVES

Variations in vascular anatomy (VIVAs) of the retroperitoneal great vessels are uncommon but can potentially complicate surgical procedures and negatively affect treatment outcomes, yet their incidence and clinical impact are poorly studied. We sought to assess the incidence and clinical impact of VIVAs of retroperitoneal great vessels in patients with retroperitoneal tumors.

METHODS

We retrospectively analyzed imaging, surgical, treatment and survival data of all pediatric patients with retroperitoneal tumors who underwent resection between January 2007 and October 2016, comparing preoperative scans with corresponding intraoperative observations, and subsequent surgical outcomes.

RESULTS

Among 66 children with renal, adrenal and paravertebral tumors, 6 (9%) had retroperitoneal VIVAs. Retroperitoneal VIVAs were present only with right-sided tumors and significantly associated with more frequent intraoperative complications (P = 0.013). While the presence of retroperitoneal VIVAs was not directly associated with survival outcomes, relapse was more frequent in patients with VIVAs (33%) than those without (18.3%, P = 0.378), and relapse was also associated with lower overall and event-free survival (P < 0.001).

CONCLUSIONS

VIVAs of retroperitoneal great vessels occurred in 9% of our patients with retroperitoneal tumors. Retroperitoneal VIVAs were associated with higher rates of intraoperative complications and disease relapse but was not directly related to survival outcomes.

TYPE OF STUDY

Retrospective review study.

LEVEL OF EVIDENCE

Level III Retrospective comparative study.

Evaluation of a Novel Bony Landmark-Based Method for Teaching Percutaneous Insertion of Subclavian Venous Catheters in Pediatric Patients

BACKGROUND

Surgical trainees performing subclavian vein (SCV) cannulation often incorrectly perceive needle trajectory and anatomical relations. As surface landmark-based methods derived from adult surgical practice may be less effective in younger patients, we developed and evaluated a novel bony landmark-based method for teaching SCV cannulation for central venous access device (CVAD) placement in children.

METHODS

Over 2 sequential 3-year periods, pediatric surgical trainees were taught infraclavicular SCV cannulation via surface- and bony-landmark approaches, respectively. We prospectively recorded patient, surgeon and operative details on all Hickman line and port-a-cath insertions placed by trainees as the first surgeon via percutaneous infraclavicular SCV puncture and compared procedural outcomes and complications across both periods.

RESULTS

Of 271 cases included in the study, trainees performed 52 (50.5%) and 92 (54.8%) procedures in the first and second periods, respectively. Patients in both periods did not differ by gender, disease, CVAD device, or prior CVAD, chemotherapy or infection status. In the second (bony landmark) period, although patients were younger (6.0 vs. 8.7 years, P = 0.003) mean procedural duration was shorter (42.5 vs. 58.3 min, P < 0.001). Also, cannulation attempts and complication rates did not differ significantly between study periods (P = 0.257 and 1.0, respectively).

CONCLUSIONS

With the bony landmark approach, trainees could perform the procedures faster despite operating on younger patients, without impacting complication rates and cannulation attempts. Bony landmarks may better approximate SCV position across a range of ages, thus improving the consistency of SCV cannulation in CVAD placements in children.

Clinical relevance of screening checklists for detecting cancer predisposition syndromes in Asian childhood tumours

Assessment of cancer predisposition syndromes (CPS) in childhood tumours is challenging to paediatric oncologists due to inconsistent recognizable clinical phenotypes and family histories, especially in cohorts with unknown prevalence of germline mutations. Screening checklists were developed to facilitate CPS detection in paediatric patients; however, their clinical value have yet been validated. Our study aims to assess the utility of clinical screening checklists validated by genetic sequencing in an Asian cohort of childhood tumours. We evaluated 102 patients under age 18 years recruited over a period of 31 months. Patient records were reviewed against two published checklists and germline mutations in 100 cancer-associated genes were profiled through a combination of whole-exome sequencing and multiplex ligation-dependent probe amplification on blood-derived genomic DNA. Pathogenic germline mutations were identified in ten (10%) patients across six known cancer predisposition genes: TP53, DICER1, NF1, FH, SDHD and VHL. Fifty-four (53%) patients screened positive on both checklists, including all ten pathogenic germline carriers. TP53 was most frequently mutated, affecting five children with adrenocortical carcinoma, sarcomas and diffuse astrocytoma. Disparity in prevalence of germline mutations across tumour types suggested variable genetic susceptibility and implied potential contribution of novel susceptibility genes. Only five (50%) children with pathogenic germline mutations had a family history of cancer. We conclude that CPS screening checklists are adequately sensitive to detect at-risk children and are relevant for clinical application. In addition, our study showed that 10% of Asian paediatric solid tumours have a heritable component, consistent with other populations.

XAF1 promotes neuroblastoma tumor suppression and is required for KIF1Bβ-mediated apoptosis

Neuroblastoma is an aggressive, relapse-prone childhood tumor of the sympathetic nervous system. Current treatment modalities do not fully exploit the genetic basis between the different molecular subtypes and little is known about the targets discovered in recent mutational and genetic studies. Neuroblastomas with poor prognosis are often characterized by 1p36 deletion, containing the kinesin gene KIF1B. Its beta isoform, KIF1Bβ, is required for NGF withdrawal-dependent apoptosis, mediated by the induction of XIAP-associated Factor 1 (XAF1). Here, we showed that XAF1 low expression correlates with poor survival and disease status. KIF1Bβ deletion results in loss of XAF1 expression, suggesting that XAF1 is indeed a downstream target of KIF1Bβ. XAF1 silencing protects from NGF withdrawal and from KIF1Bβ-mediated apoptosis. Overexpression of XAF1 impairs tumor progression whereas knockdown of XAF1 promotes tumor growth, suggesting that XAF1 may be a candidate tumor suppressor in neuroblastoma and its associated pathway may be important for developing future interventions.

Abstract A47: Unusual suspects identified in neuroblastoma: An unexpected tumor suppression pathway

Developmental apoptosis of neural crest precursors is crucial in determining the final number of terminally differentiated cells such as sympathetic neurons. During neural development, cells undergo apoptosis as NGF becomes limiting. Aberrant developmental apoptosis is implicated in pediatric sympathetic nervous system tumors. When NGF becomes limiting, a developmental apoptotic pathway is activated which requires KIF1Bbeta. KIF1Bbeta is necessary and sufficient for apoptosis during NGF withdrawal. KIF1Bbeta maps to 1p36.2, a frequently deleted region in neuroblastomas, and a neural crest-derived cancer. We identified that KIF1Bbeta-induced apoptosis requires RNA/DNA helicase DHX9. KIF1Bbeta interacts with DHX9 to enhance translocation and accumulation of cytoplasmic DHX9 in the nucleus, resulting in transcription of apoptotic XAF1. Transcription-incompetent DHX9 is unable to potentiate KIF1Bbeta-induced cell death. Knockdown of DHX9 also protects from KIF1Bbeta-induced cell death whereas KIF1Bbeta loss-of-function domains or patient-associated point mutants are unable to translocate and accumulate cytoplasmic DHX9 in the nucleus, impairing XAF1 expression. Furthermore, XAF1 silencing protects from KIF1Bbeta-induced and NGF withdrawal-mediated apoptosis in vitro as well as promotes tumor growth in vivo whereas XAF1 overexpression is necessary and sufficient to induce apoptosis in vitro and delays tumor growth in vivo. Conditional knockout of KIF1Bbeta in the superior cervical ganglia neurons of mouse pups also specifically ablates XAF1 expression in vivo and ex vivo, suggesting that KIF1Bbeta and XAF1 are tightly regulated and act along the same pathway. Clinically, tissue microarray analysis of pre-treatment or post-treatment neuroblastoma patients who are 1p-intact or 1p-deleted, revealed strong prognostic significance of XAF1 expression in disease stratification. Our findings provide a mechanistic understanding on the development of neuroblastoma through unexpected candidates of tumorigenesis.

Citation Format: Zhang'e Choo, Rachel Yu Lin Koh, Karin Wallis, Timothy Jia Wei Koh, Chik Hong Kuick, Veronica Sobrado, Amos Hong Pheng Loh, Shui Yen Soh, Susanne Schlisio, Kenneth Tou En Chang, Zhi Xiong Chen. Unusual suspects identified in neuroblastoma: An unexpected tumor suppression pathway. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Pediatric Cancer Research: From Mechanisms and Models to Treatment and Survivorship; 2015 Nov 9-12; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(5 Suppl):Abstract nr A47.

Thyroglossal duct cyst carcinoma: diagnostic and management considerations in a 15-year-old with a large submental mass

A 15-year old boy presented with a 2-year history of a painless slowly enlarging submental neck mass. Head and neck imaging showed a multicystic mass with a central solid component that was closely applied to the hyoid bone. Core needle biopsy under general anaesthesia revealed a papillary thyroid neoplasm. The mass was resected and frozen section histology confirmed papillary carcinoma. Intraoperatively, enlarged cervical lymph nodes were palpable. Bilateral neck dissections and total thyroidectomy with parathyroid reimplantation were performed. On histological examination, the thyroid gland was not involved. The patient recovered uneventfully from the surgery and is planned for radioactive iodine therapy and thyroxine suppression, with subsequent follow-up with serum thyroid-stimulating hormone and thyroglobulin for surveillance. We review the literature and discuss challenges in the diagnosis and surgical management of this rare entity in the paediatric age group.

Novel Karyotypes and Cyclin D1 Immunoreactivity in Clear Cell Sarcoma of the Kidney

Pathological diagnosis of clear cell sarcoma of the kidney (CCSK) is challenging as it resembles blastemal Wilms tumor (WT) and other pediatric sarcomas, and does not have any distinctive immunophenotype. The YWHAE-FAM22 translocation t(10;17)(q22;p13) has been reported in a subset of CCSK. This translocation also occurs in high-grade endometrial sarcoma, in which it is associated with cyclin D1 overexpression. Hence we seek to determine YWHAE-FAM22 translocation status and cyclin D1 immunoreactivity in a series of local CCSK cases. Of 8 CCSK cases from 7 patients identified, no CCSK had the YWHAE-FAM22 fusion transcript by reverse transcriptase-polymerase chain reaction. Novel karyotypes were identified for 2 cases: 1 had t(2;13)(q13;q22) and the other t(3:17)(q29;p11.2). Excluding a case with poor tissue section antigenicity, 7 of 7 CCSKs (100%) showed diffuse and strong nuclear cyclin D1 staining. Cyclin D1 immunohistochemistry was also performed on tissue microarrays of other pediatric renal tumors: blastemal areas of 18 WT cases were negative; 6 rhabdoid tumors and 1 metanephric adenoma showed patchy and weak staining; 3 mesoblastic nephromas and 18 of 29 neuroblastomas had positive staining. Cyclin D1 immunohistochemistry helps distinguish CCSK from blastemal WT and metanephric adenoma and rhabdoid tumors, but not from neuroblastomas and mesoblastic nephromas. Cyclin D1 overexpression in CCSK is not contingent on YWHAE-FAM22 translocation, and cyclin D1 inhibition may potentially be explored as a targeted therapeutic strategy in CCSK.

Diagnostic accuracy of preoperative alpha-fetoprotein as an ovarian tumor marker in children and adolescents: not as good as we thought?

PURPOSE

To evaluate the diagnostic accuracy of preoperative serum alpha-fetoprotein (AFP) levels in predicting malignancy risk in children and adolescents presenting with ovarian neoplasms.

METHODS

In 110 girls aged 18 and below diagnosed with ovarian neoplasms, we retrospectively correlated preoperative serum AFP levels with histological diagnosis of germ cell tumor or immature teratoma (GCT/IT) versus non-GCT/IT, and benign versus non-benign. We determined area under receiver-operating characteristic curves (AUC), sensitivity, specificity, and likelihood ratios.

RESULTS

Twenty patients (18.2 %) had non-benign ovarian neoplasms, of which 12 had GCT/IT (10.9 %). In diagnosing GCT/IT versus non-GCT/IT, specificity of preoperative serum AFP was 87.8 %, sensitivity 66.7 %, and AUC 0.853. Excluding infants to remove the effects of increased variance in AFP in this group, specificity improved (92.0 %), but not sensitivity (66.7 %); AUC was 0.926. Increasing AFP cutoff to two times upper normal limit improved specificity (94.9 %), but not sensitivity (66.7 %). For benign versus non-benign tumors, AFP specificity was only 88.9 % and sensitivity 50.0 %.

CONCLUSION

The diagnostic accuracy of preoperative serum AFP for detecting GCT/IT in girls was limited by poor sensitivity and positive predictive value. Excluding infants and raising cutoff levels improved specificity marginally. Clinicians should be aware of these limitations when using AFP in the preoperative evaluation of childhood ovarian neoplasms.

Diagnostic delay in pediatric solid tumors: a population based study on determinants and impact on outcomes

BACKGROUND

Despite socioeconomic and clinical progress, pediatric tumors continue to present in advanced stage, and may be due to delays in diagnosis. This study aimed to identify factors associated with diagnostic delay (time between symptom onset and diagnosis) in pediatric tumors in a population-based study, and to assess the impact of delay on subsequent outcome.

PROCEDURE

Natural logarithm of delay was retrospectively described for 390 newly diagnosed tumors reported to the Singapore Childhood Cancer Registry from 1997 to 2007. Delay was correlated with socio-demographic, disease and healthcare-system factors using multivariate linear regression, and with event-free survival (EFS) using Cox regression analysis.

RESULTS

Total median delay was 5.3 weeks (range 0.1-283.1). Shorter delay was independently associated with younger patient age (P = 0.006), abdominal and pelvic sites (P < 0.001 and P = 0.036, respectively), incidental diagnoses by healthcare staff (P = 0.002), and when pediatric emergency units were the first contacted healthcare facilities and the first to raise suspicion of malignancy (P = 0.034, and P = 0.018, respectively). These factors explained only a small percentage of variance in delay times (21%). Delay was not associated with EFS and disease stage, with 24% of tumors presenting in stage 4.

CONCLUSIONS

Diagnostic delay was independently associated with age and site of presentation, and points of first symptom detection, first healthcare contact, and first suspicion of malignancy. The broad range of clinical variables analyzed could only account in a small way for differences in delay times observed. While overall delay times were short, they did not influence disease stage at presentation and eventual outcome.

Gene expression of TRK neurotrophin receptors in advanced neuroblastomas in Singapore--a pilot study

The clinical hallmark of neuroblastoma is heterogeneity. Biologically, ploidy and N-Myc amplification are currently the only 2 features used to define risk group and to determine therapy. Tyrosine kinase neurotrophin receptors (Trks, including TrkA, TrkB, and TrkC) are important in the clinical and biological behavior of neuroblastomas. The authors aim to study Trks gene expression in their local population of advanced neuroblastoma patients. Multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) assay on the expression of TrkA, TrkB, TrkB-truncated, and TrkC was performed on a total of 19 advanced neuroblastoma archival tumors, diagnosed in KK Women's and Children's Hospital between 2003 and 2007. Of the 19 tumors investigated, Trks expression was present in 14 (73.6%) cases. Of these cases, 8 (42.1%), 10 (52.6%), 7 (36.8%), and 6 (31.6%) expressed TrkA, TrkB, TrkB-truncated, and TrkC receptor mRNAs, respectively. Subsequently, the authors compared Trks expression with N-Myc amplification status of the 19 patients. N-Myc was amplified in 5 (26.3%) of the cases. Within the non-N-Myc-amplified group, Trks expression was present in 9 (64%) of the 14 cases. The significant expression of Trk isoforms among advanced neuroblastoma cases as evident from this study support their role as possible risk assessment tools alongside N-Myc amplification status.

Multiple indomethacin-induced colonic perforations in an adolescent

Colonic perforation is an uncommon cause of acute abdomen in paediatric patients, and can present a diagnostic enigma as well as management challenge to the paediatric surgeon. An adolescent developed multiple colonic perforations following a short course of oral indomethacin, requiring emergency hemicolectomy. This is the youngest known case of enteral non-steroidal anti-inflammatory drug (NSAID)-mediated large bowel injury. We review current evidence on NSAID-related enteropathy, and postulate potentiating mechanisms that may have accounted for the unusually rapid clinical course of our patient.

Port-A-Cath insertions in acute leukemia: does thrombocytopenia affect morbidity?

BACKGROUND

Unnecessary delay of insertion of Port-A-Cath indwelling venous catheters in thrombocytopenic patients may result from fear of potential morbidity. This study sought to compare the morbidity of Port-A-Cath insertions in acute leukemic patients with platelet counts below and above 50 x 10(9)/L.

METHOD

Incidence and profile of catheter-related bloodstream infections (CRBSIs) and other complications were determined in 80 consecutive Port-A-Cath insertions in pediatric patients with acute leukemia from January 2002 to December 2004. Subgroup analysis was performed for patients with platelet levels below and above the recommended safe level of 50 x 10(9)/L.

RESULTS

Twenty-two (27.5%) patients had insertions performed at platelet levels below the recommended level (median, 35.3; range, 10-49 x 10(9)/L); postoperative counts were correspondingly higher (median, 66.0; range, 20-207 x 10(9)/L) with perioperative platelet transfusion. Catheter-related bloodstream infection incidence was similar in patients with platelets less than and greater than the recommended threshold (18.2% vs 17.2%, respectively), and likewise for CRBSIs encountered in the immediate 30 postoperative days (4.6% and 5.2%, respectively). Only 2 episodes of postoperative bleeding occurred, both in the group with platelet counts greater than 50 x 10(9)/L, with an equally low incidence of other local and mechanical complications in both subgroups. Patient demographics and other preoperative blood parameters did not differ significantly.

CONCLUSION

Preoperative thrombocytopenia was not associated with increased incidence of postoperative complications for Port-A-Cath insertions in acute leukemic children.