Risk of venous thromboembolism in pediatric patients with brain tumors

Proportion and risk factors for hospital-acquired venous thromboembolism in children: a systematic review and meta-analysis of data from 20 million individuals in 22 countries

Background

Hospital-acquired venous thromboembolism (HA-VTE) in children has been widely regarded.

Objectives

We aimed to analyze the proportion and risk factors for HA-VTE in hospitalized children.

Methods

We conducted a comprehensive systematic search across 4 databases from 1990 to 2023. Cochran Q test was used to evaluate the heterogeneity of the effect sizes of study, and I2 statistic was used to quantify the heterogeneity. Pooled estimates were calculated by the inverse-variance weighted method in a fixed-effect model or a random-effect model when heterogeneity was low (I2 < 25%) or high (I2 > 25%), respectively.

Results

In total, 105 original papers and 20,718,294 patients were included in the study, and the proportion of HA-VTE in children was 4.1% (95% CI, 2.9%-5.2%). Although the proportion of venous thromboembolism increased over the various research periods, the differences were not statistically significant. In the subgroup analysis based on country, the proportion of pediatric HA-VTE was lowest in the United Kingdom and highest in Spain, whereas when based on region, the proportion was lowest in Asia and highest in North America. Multiple HA-VTE risk factors were identified, including central venous catheter use, age of >10 years, surgery, injury, infection, obesity, mechanical ventilation, blood transfusion, malignancy, coagulation and hemorrhagic disorders, and length of hospital stay.

Conclusion

In this study, we systematically analyzed the proportion and risk factors of HA-VTE in hospitalized children. Our findings provide valuable insights for the prevention and treatment of HA-VTE in pediatric patients.

Vascular complications in craniopharyngioma-resected paediatric patients: a single-center experience

Background

Craniopharyngioma (CP), although slow growing and histologically benign, has high morbidity, mostly related to hypothalamus-pituitary dysfunction and electrolyte imbalance. Increased risk of vascular complications has been described. However, data are still poor, especially in the paediatric population. The aim of our study was to evaluate the occurrence, timing, and predisposing factors of deep venous thrombosis (DVT) and other vascular alterations in neurosurgical paediatric CP patients.

Materials and Methods

In a single-centre, retrospective study, we investigated 19 CP patients (11 males, 8 females, mean age 10.5 ± 4.3 years), who underwent neurosurgery between December 2016 and August 2022, referred to Meyer Children's Hospital IRCCS in Florence.

Results

Five patients (26.3%) presented vascular events, which all occurred in connection with sodium imbalances. Three DVT (two with associated pulmonary embolism, in one case leading to death) developed in the post-operative period, most frequently at 7-10 days. Elevated D-dimers, a reduced partial activated thrombin time and a prolonged C-reactive protein increase were highly related to thrombotic vascular events. One case of posterior cerebral artery pseudoaneurysm was described soon after neurosurgery, requiring vascular stenting. Superficial vein thrombophlebitis was a late complication in one patient with other predisposing factors.

Conclusion

CP patients undergoing neurosurgery are at risk of developing DVT and vascular alterations, thus careful follow-up is mandatory. In our study, we found that the phase of transition from central diabetes insipidus to a syndrome of inappropriate antidiuretic hormone secretion may be a period of significant risk for DVT occurrence. Careful vascular follow-up is mandatory in CP-operated patients.

Thrombosis and Anticoagulant Therapy Among Pediatric Cancer Patients: Real-Life Data

Background: Venous thromboembolism (VTE) in children is relatively rare, and more so among those with cancer. In this study, we report the characteristics and outcomes of children with cancer-associated thrombosis.

Methods: We reviewed institutional databases for all children with cancer and a diagnosis of VTE at King Hussein Cancer Center in Jordan. Variables reviewed are patients’ clinical characteristics, treatment for cancer, and anticoagulation therapy.

Results: Between January 2011 and December 2018, a total of 45 patients fulfilled the inclusion criteria, and the median age was 10.4 (0.8-17.9) years. The most common underlying diagnosis was acute lymphoblastic leukemia (n = 13, 29%). At the time of VTE, 29 (64.4%) patients were receiving chemotherapy, and eight (17.8%) had a central venous catheter (CVC). The majority of patients (n = 37, 82%) developed VTE within 30 days of hospitalization. Thrombosis mostly involved the extremities (n = 23, 51%) and sagittal vein (n = 12, 26.7%). All patients were treated with low-molecular-weight heparin (LMWH), complicated by bleeding in three (6.6%) patients.

Conclusion: In contrast to adults, VTE in pediatric cancer patients is more associated with chemotherapy and recent hospitalization. LMWH is a safe and effective therapy for children with cancer who develop VTE.

Venous Thromboembolism Risk and Thromboprophylaxis in Pediatric Neurosurgery and Spinal Injury: Current Trends and Literature Review

Although the entities of venous thromboembolism (VTE), deep venous thrombosis, pulmonary embolus, and thromboprophylaxis in adult patients undergoing brain tumor and spine surgery, traumatic brain injury and elective neurosurgical procedures are widely elucidated, the same is not valid when pediatric patients are under consideration. An attempt to review the peculiarities of these patients through a comprehensive bibliographic review is undertaken. We performed a narrative summary of the relevant literature dedicated to pediatric patients, centered on traumatic brain injury, the general incidence of thromboembolic disease in this patient population, the role of low molecular weight heparin (LMWH) in the treatment and prophylaxis of VTE, and its role in elective neurosurgical procedures, including spinal operations. Additionally, the risk of deep venous thrombosis in elective neurosurgical procedures is reviewed. Due to inherent limitations of the current studies, particularly a restricted number of patients, our data are underpowered to give a definitive protocol and guidelines for all the affected patients. Our current conclusions, based only on pediatric patients, argue that there is limited risk of VTE in pediatric patients suffering from brain tumors and that the possibility of VTE is very low in children undergoing elective neurosurgical procedures. There is no consensus regarding the exact incidence of VTE in traumatic brain injury patients. LMWH seems to be a safe and effective choice for the "at risk" pediatric patient population defined as being older than 15 years, venous catheterization, nonaccidental trauma, increased length of hospital stays, orthopaedic (including spinal) surgery, and cranial surgery.

Venous thromboembolism in children with central nervous system tumors: Comparison of an institutional cohort to a national administrative database

BACKGROUND

Central nervous system (CNS) tumors are the second most common malignancy of childhood, and published data on venous thromboembolism (VTE) rate and risk factors for these patients are outdated or incomplete. Here, we determine the cumulative incidence and risk factors for VTE in this population.

PROCEDURE

VTE diagnosis and associated clinical risk factors were abstracted and analyzed for two cohorts of children (0-21 years) diagnosed with CNS tumors between January 1, 2010 to September 30, 2018. The first study was a retrospective single institution cohort study. The initial observations were confirmed across multiple pediatric hospitals using the Pediatric Health Information System (PHIS) administrative database.

RESULTS

The single-institution cohort included 338 patients aged 3 days to 20.9 years (median age, 8.6 years); VTE developed in eight (2.4%) patients. The PHIS cohort included 17 634 patients aged from 0 to 21.9 years (median: 9.5 years); VTE developed in 354 (2.0%) patients. Univariate analysis for the single-institution cohort identified central venous catheter (CVC) placement as a risk factor for VTE (odds ratio [OR] 8.40, 95% confidence interval [CI] 1.43-49.41, P = .0186). Multivariable analysis of the PHIS dataset identified CVC placement (OR 1.97, 95% CI 1.57-2.46; P < .0001), obesity (OR 2.96, 95% CI 1.21-7.26; P = .0177), and more than one hospital admission (OR 3.54, 95% CI 2.69-4.64; P < .0001) as significant predictors of VTE. VTE diagnosis was not associated with increased mortality in either cohort.

CONCLUSIONS

The VTE rate in children with CNS tumors is low (2%). CVC placement was identified as a modifiable risk factor in both cohorts.

Incidence and risk factors of venous thrombotic events in pediatric patients with CNS tumors compared with non-CNS cancer: A population-based cohort study

BACKGROUND

Venous thromboembolism (VTE) is a well-recognized complication in pediatric cancer patients. It has been demonstrated that the incidence of VTE in pediatric patients with central nervous system (CNS) tumors is lower than that of patients with other cancers. Risk factors for developing cancer-related thrombosis are numerous and can include patient, disease, or treatment-related influences. The present study was designed to assess the VTE incidence in a pediatric oncology population, and to investigate whether intensity of treatment has similar associated with risk of VTE development in patients with and without CNS tumors.

METHODS

A retrospective population-based cohort study of pediatric oncology patients in Atlantic Canada was conducted. Data collected from medical records included demographics, cancer type, treatment, presence of central venous catheters (CVC), and presence of thrombosis. Treatment intensity was assessed using the intensity of treatment rating scale (ITR-3). Study period was from January 2000 to December 2017. SPSS version 24 was used for statistical analysis.

RESULTS

Of 1262 patients with pediatric cancer, 247 (19.6%) had CNS tumors. VTE occurred in significantly fewer (n = 5, 2%) patients with CNS tumors compared with patients with non-CNS cancers (n = 79, 7.8%) (p = 0.001). The ITR-3 scores did not differ significantly between the CNS and non-CNS groups (p = 0.638). In a multivariate logistic regression analysis, ITR-3 score was associated with VTE (odds ratio [OR]: 1.48, 95% CI: 1.2-1.9), while presence of CNS tumor was protective (OR: 0.26, 95% CI: 0.1-0.6).

CONCLUSIONS

We demonstrate that pediatric patients with CNS tumors experience a significantly lower incidence of VTE compared with patients with non-CNS cancer. An increase in the ITR-3 rating significantly increased the odds of developing VTE.

Pediatric CNS Tumor Patients Have Significantly Lower Requirement of Tissue Plasminogen Activator for Episodes of Central Venous Catheter Dysfunction Compared With Other Pediatric Oncology Patients: Results of a Population-based Cohort Study

PURPOSE

Central venous catheters (CVCs) are an important component of care delivery in pediatric oncology patients. However, CVC dysfunction is a common problem. Tissue plasminogen activator (tPA) is often administered to re-establish function, however, specific experience in pediatric patients with central nervous system (CNS) tumors is lacking. The goal of this study was to investigate the CVC experience and use of tPA for episodes of CVC dysfunction in pediatric patients with CNS tumors in comparison with other patients.

METHODS

Medical records of all pediatric oncology patients from the 4 Atlantic provinces in Canada (Nova Scotia, New Brunswick, Prince Edward Island, and Newfoundland and Labrador) were reviewed. Data collected included demographics, treatment, details of CVCs along with CVC dysfunction, and tPA use.

RESULTS

The cohort consisted of 1152 pediatric oncology patients, 222 (19.3%) of whom had CNS tumors. CVC dysfunction requiring tPA administration occurred in 12 (5.4%) of patients with CNS tumors compared with 182 (19.6%) of patients with non-CNS tumors (P=0.0001). Multivariate logistic regression analysis showed that administration of tPA for CVC dysfunction was 2.5 times more likely in patients with non-CNS tumors than those with CNS tumors (P=0.012; 95% confidence interval, 1.3-4.9).

CONCLUSIONS

Our study showed that pediatric patients with CNS tumors require significantly less frequent administration of tPA for episodes of CVC dysfunction than patients with non-CNS tumors after adjusting for confounding factors. Hypotheses for this include: potential biologic differences of tumors, the role of the blood-brain barrier, or systematic differences in intensity of treatments.

Single cell coagulomes as constituents of the oncogene-driven coagulant phenotype in brain tumours

Molecular profiling of human cancers revealed a startling diversity in disease-causing mechanisms superseding histological and anatomical commonalities. The emerging molecular subtypes and disease entities are often driven by distinct oncogenic pathways and their effectors, including those acting extracellularly on the vascular and coagulation systems. Indeed, several oncogenic mutations such as those affecting protein-coding genes (RAS, EGFR, PTEN, TP53) and non-coding RNA (microRNA) regulate multiple effectors of the coagulation system (coagulome), including tissue factor, protease activated receptors, clotting factors, mediators of platelet function and fibrinolysis. This is exemplified by differential coagulome profiles in the molecular subtypes of glioblastoma, medulloblastoma and other human tumours. There is mounting clinical evidence that the mutational status of cancer driver genes such as KRAS or IDH1 may influence the risk of venous thromboembolism in patients with colorectal, lung or brain cancers. Notably, single cell sequencing in glioblastoma revealed a remarkable intra-tumoural heterogeneity of cancer cell populations with regard to their individual coagulomes, suggesting a combinatorial and dynamic nature of the global pro-thrombotic phenotype. We suggest that the cellular complexity of specific cancers may define their mechanisms of interactions with the coagulation system, and the risks of thrombosis. Thus, more biologically- based, disease-specific and personalized approaches may be needed to diagnose and manage cancer-related thrombosis.

Chemical venous thromboembolism prophylaxis in neurosurgical patients: an updated systematic review and meta-analysis

OBJECTIVE

Venous thromboembolism (VTE) is a common and potentially life-threatening complication. The risk of serious hemorrhagic complications when starting chemical prophylaxis for VTE prevention is a substantial concern for neurosurgeons. The objective of this study was to perform an updated systematic review and meta-analysis to determine if the rates of VTE and bleeding complications are different in patients undergoing chemoprophylaxis compared with placebo or mechanical prophylaxis alone following cranial or spinal procedures.

METHODS

In February 2016 a systematic literature review was performed identifying 3944 articles from 4 different databases. A random-effects meta-analysis was performed after identifying the articles that met inclusion criteria.

RESULTS

Nine articles that met the inclusion criteria were included. The quality of the studies was good, with all of them being classified as Level 2 evidence, with moderate Jadad scores. A meta-analysis comparing chemoprophylaxis with placebo in the prevention of deep venous thrombosis showed a significant benefit to chemical prophylaxis (OR 0.51, 95% CI 0.37–0.71; p < 0.0001). No significant increase in major intracranial hemorrhage (p = 0.60), major extracranial hemorrhage (p = 0.98), or minor bleeding complications (p = 0.60) was found.

CONCLUSIONS

Based on moderate-to-good quality of evidence, chemoprophylaxis is beneficial in preventing VTE, with no significant increase in either major or minor bleeding complications in patients undergoing cranial and spinal procedures. Further research is needed to determine whether this conclusion holds true for more specific subpopulations.

Venous thromboembolic complications with and without intermittent intraoperative and postoperative pneumatic compression in patients with glioblastoma multiforme using intraoperative magnetic resonance imaging. A retrospective study

OBJECTIVE

To evaluate the effectiveness of intraoperative and postoperative intermittent pneumatic compression (IPC) as a method used to decrease the incidence of deep venous thrombosis (DVT), in comparison to the standard use of graduated compression stockings, low-molecular weight heparin (LMWH) and physiotherapy during the hospital stay. All patients in this study underwent intracranial surgery for glioblastoma multiforme (GBM) using intraoperative magnetic resonance imaging (MRI) guidance.

PATIENTS AND METHODS

We performed a single center retrospective study of a cohort of 153 patients who underwent surgery for GBM aided by intraoperative MRI from October of 2009 to January of 2015 at the International Neuroscience Institute (INI), Hannover, Germany. Out of all patients, 75 in comparison to 78 were operated with and without the additional use of IPC, respectively. Both groups received graduated compression stockings, LMWH and physiotherapy postoperatively as a basic thromboprophylaxis. Postoperatively the patients were screened for DVT by Doppler ultrasonography of the limbs and pulmonary embolism (PE) by CT-scan of the chest.

RESULTS

DVTs were found in 6 patients with IPC and in 3 patients without IPC. The incidence of developing DVTs was therefore not significantly increased with the application of IPC from 3.9% to 8% (P-value: 0.33). No statistically significant differences were found in the probability of occurrence of pulmonary embolism (PE) with a reduction from 2.6% to 1.3% (P-value: 0.59).

CONCLUSION

Our results demonstrate, that the surgical intervention and the subsequent patient immobilization, as well as the thromboprophylactic techniques used have a relatively low influence on the occurrence of thromboembolic complications than we expected. Our findings might be attributed to the overall low number of these complications in a glioblastoma multiforme patient population expected to be at a high risk for coagulopathy. In other words, in order to produce statistically significant results, we would need to increase the patient cohort. By doing so we may better detect a positive therapeutic effect. Alternatively, because of the multitude of possible complex risk-factors leading to coagulopathy in a glioblastoma patient population it might be the case that IPC has little or no effect and that there is a different underlying mechanism responsible for the observed coagulopathy.

The association of venous thromboembolism with survival in pediatric cancer patients: a population-based cohort study

Venous thromboembolism (VTE) is a well-recognized complication in pediatric oncology patients. Studies in adult oncology patients have suggested a potential negative association between VTE and survival, but this association has not been examined in pediatric patients yet. The aim of this study was to assess the association of VTE with survival in pediatric oncology patients. Data from all pediatric oncology patients treated at the two tertiary care centers in Atlantic Canada were pooled to create a population-based cohort. The association between VTE and survival was analyzed using a Cox proportional hazards model stratified by diagnosis group (leukemia, lymphoma, and other; sarcoma) and adjusted for age at diagnosis and sex. Out of 939 patients included in this study, 73 had a VTE (8%) and 131 (14%) patients died during the study period. Children in the leukemia/lymphoma/other group with a VTE had significantly poorer survival relative to children in the same group who did not have a VTE. Although children with sarcoma and VTE had poorer survival compared to children with sarcoma with no VTE, this association was not statistically significant. In this population-based study, we found a negative association between VTE and survival in pediatric oncology patients. If future studies confirm this association, this finding may have prognostic implications and potentially offer new avenues for the management of pediatric patients with cancer.

Risk of Deep vein thrombosis in neurosurgery: State of the art on prophylaxis protocols and best clinical practices

OBJECTIVE

To analytically discuss some protocols in Deep vein thrombosis (DVT)/pulmonary Embolism (PE) prophylaxis currently use in Neurosurgical Departments around the world.

DATA SOURCES

Analysis of the prophylaxis protocols in the English literature: An analytical and narrative review of literature concerning DVT prophylaxis protocols in Neurosurgery have been conducted by a PubMed search (back to 1978).

DATA EXTRACTION

80 abstracts were reviewed, and 74 articles were extracted.

DATA ANALYSIS

The majority of DVT seems to develop within the first week after a neurosurgical procedure, and a linear correlation between the duration of surgery and DVT occurrence has been highlighted. The incidence of DVT seems greater for cranial (7.7%) than spinal procedures (1.5%). Although intermittent pneumatic compression (IPC) devices provided adequate reduction of DVT/PE in some cranial and combined cranial/spinal series, low-dose subcutaneous unfractionated heparin (UFH) or low molecular-weight heparin (LMWH) further reduced the incidence, not always of DVT, but of PE. Nevertheless, low-dose heparin-based prophylaxis in cranial and spinal series risks minor and major postoperative haemorrhages: 2-4% in cranial series, 3.4% minor and 3.4% major haemorrhages in combined cranial/spinal series, and a 0.7% incidence of major/minor haemorrhages in spinal series.

CONCLUSION

This analysis showed that currently most of the articles are represented by case series and case reports. As long as clear guidelines will not be defined and universally applied to this diverse group of patients, any prophylaxis for DVT and PE should be tailored to the individual patient with cautious assessment of benefits versus risks.

Risk of deep venous thrombosis in elective neurosurgical procedures: a prospective, Doppler ultrasound-based study in children 12 years of age or younger

OBJECTIVE The risk of venous thromboembolism (VTE) from deep venous thrombosis (DVT) is significant in neurosurgical patients. VTE is considered a leading cause of preventable hospital deaths and preventing DVT is a closely monitored quality metric, often tied to accreditation, hospital ratings, and reimbursement. Adult protocols include prophylaxis with anticoagulant medications. Children's hospitals may adopt adult protocols, although the incidence of DVT and the risk or efficacy of treatment is not well defined. The incidence of DVT in children is likely less than in adults, although there is very little prospectively collected information. Most consider the risk of DVT to be extremely low in children 12 years of age or younger. However, this consideration is based on tradition and retrospective reviews of trauma databases. In this study, the authors prospectively evaluated pediatric patients undergoing a variety of elective neurosurgical procedures and performed Doppler ultrasound studies before and after surgery. METHODS A total of 100 patients were prospectively enrolled in this study. All of the patients were between the ages of 1 month and 12 years and were undergoing elective neurosurgical procedures. The 91 patients who completed the protocol received a bilateral lower-extremity Doppler ultrasound examination within 48 hours prior to surgery. Patients did not receive either medical or mechanical DVT prophylaxis during or after surgery. The ultrasound examination was repeated within 72 hours after surgery. An independent, board-certified radiologist evaluated all sonograms. We prospectively collected data, including potential risk factors, details of surgery, and details of the clinical course. All patients were followed clinically for at least 1 year. RESULTS There was no clinical or ultrasound evidence of DVT or VTE in any of the 91 patients. There was no clinical evidence of VTE in the 9 patients who did not complete the protocol. CONCLUSIONS In this prospective study, no DVTs were found in 91 patients evaluated by ultrasound and 9 patients followed clinically. While the study is underpowered to give a definitive incidence, the data suggest that the risk of DVT and VTE is very low in children undergoing elective neurosurgical procedures. Prophylactic protocols designed for adults may not apply to pediatric patients. Clinical trial registration no.: NCT02037607 (clinicaltrials.gov).

Pediatric cerebral sinovenous thrombosis following cranial surgery

PURPOSE

Pediatric cerebral sinovenous thrombosis (CSVT) is an important, though less common subtype of pediatric stroke. It has been linked to several risk factors, including cranial procedures, with few studies highlighting this relationship. The aim of this study was to characterize the diagnosis and treatment of CSVT after cranial surgery.

METHODS

An institutional pediatric stroke research database was used to identify all CSVT cases diagnosed within 30 days of cranial surgery from November 2004 to December 2014. Thirteen subjects were retrospectively analyzed for clinical presentation, surgical details, radiographic characteristics, laboratory study results, treatment, and outcome. Diagnostic testing and treatment adhered to a consensus-based institutional stroke protocol.

RESULTS

Cranial vault reconstruction, subdural empyema evacuation, and tumor resection were each observed in three subjects. Eleven (85%) subjects had sinus exposure during surgery, and eight (73%) developed thrombus in a sinus within or adjacent to the operative field. Two (15%) had documented iatrogenic sinus injury. On post-operative testing, ten (77%) subjects had prothrombotic abnormalities. Seven (54%) were treated with anti-coagulation therapy (ACT) starting on a median of post-operative day (POD) 3 (IQR 1-3) for a median of 2.9 months (IQR 2.4-5.4). Median time to imaging evidence of partial or complete recanalization was 2.4 months (IQR 0.7-5.1). No symptomatic hemorrhagic complications were encountered.

CONCLUSIONS

Pediatric CSVT may be encountered after cranial surgery, and decisions related to anti-coagulation are challenging. The risk of CSVT should be considered in pre-surgical planning and post-operative evaluation of cases with known risk factors. In our study, judicious use of ACT was safe in the post-operative period.

Incidence and characteristics of venous thrombotic events in pediatric cancer patients: A 20-year experience in the Maritimes, Canada

OBJECTIVE

Venous thrombotic events (VTE) are a well-recognized complication in pediatric cancer patients. Population-based data on the incidence and characteristics of VTE in all pediatric cancer patients are limited. This information is crucial to identify patients at high risk and design targeted interventions accordingly. The present study was designed to determine the incidence and characteristics of VTE in the pediatric oncology population.

PARTICIPANTS

We conducted a retrospective, population-based, cohort study of patients treated in the Maritimes, Canada between 1995 and 2015.

RESULTS

There were 1210 pediatric hematology/oncology patients from the Maritimes, Canada, treated at the IWK Health Centre between 1995 and 2015. Fifty-eight (4.8%) experienced at least 1 VTE and the majority of patients experienced it within 6 months of cancer diagnosis. The median age of patients who experienced VTE was 10.7 years (SD = 6.0). The most common presenting symptom of thrombosis was central venous line dysfunction, and the most common location for thrombosis was within the upper venous system. We observed that 65.6% of the patients with VTE required >1 central venous catheters (CVC). The presence of a VTE increased the odds of requiring >1 CVC to 3.6 (95% confidence interval: 1.76-7.3).

CONCLUSION

Thus, in this large, population-based study, we present the incidence and characteristics of VTE in the pediatric oncology population and demonstrate the clinical impact of VTE in terms of loss of CVC. Larger, prospective studies are required to confirm these findings and to develop a risk model for managing and preventing VTE in this patient population.

Venous Thromboembolism in Children with Cancer and Blood Disorders

Venous thromboembolism (VTE) in children is multifactorial and most often related to a combination of inherited and acquired thrombophilias. Children with cancer and blood disorders are often at risk for VTE due to disease-related factors such as inflammation and abnormal blood flow and treatment-related factors such as central venous catheters and surgery. We will review risk factors for VTE in children with leukemia, lymphoma, and solid tumors. We will also review risk factors for VTE in children with blood disorders with specific focus on sickle cell anemia and hemophilia. We will present the available evidence and clinical guidelines for prevention and treatment of VTE in these populations.

Tissue Factor Regulation by miR-520g in Primitive Neuronal Brain Tumor Cells: A Possible Link between Oncomirs and the Vascular Tumor Microenvironment

Pediatric embryonal brain tumors with multilayered rosettes demonstrate a unique oncogenic amplification of the chromosome 19 miRNA cluster, C19MC. Because oncogenic lesions often cause deregulation of vascular effectors, including procoagulant tissue factor (TF), this study explores whether there is a link between C19MC oncogenic miRNAs (oncomirs) and the coagulant properties of cancer cells, a question previously not studied. In a pediatric embryonal brain tumor tissue microarray, we observed an association between C19MC amplification and reduced fibrin content and TF expression, indicative of reduced procoagulant activity. In medulloblastoma cell lines (DAOY and UW228) engineered to express miR-520g, a biologically active constituent of the C19MC cluster, we observed reduced TF expression, procoagulant and TF signaling activities (responses to factor VIIa stimulation), and diminished TF emission as cargo of extracellular vesicles. Antimir and luciferase reporter assays revealed a specific and direct effect of miR-520g on the TF 3' untranslated region. Although the endogenous MIR520G locus is methylated in differentiated cells, exposure of DAOY cells to 5-aza-2'-deoxycytidine or their growth as stem cell-like spheres up-regulated endogenous miR-520g with a coincident reduction in TF expression. We propose that the properties of tumors harboring oncomirs may include unique alterations of the vascular microenvironment, including deregulation of TF, with a possible impact on the biology, therapy, and hemostatic adverse effects of both disease progression and treatment.

Inaugural cerebral sinovenous thrombosis revealing homocystinuria in a 2-year-old boy

Cerebral sinovenous thrombosis is unusual during childhood and requires early and accurate management because of its detrimental consequences. We report on the case of a 2-year-old boy with mild psychomotor delay, who presented with nonfebrile acute ataxia. A brain computed tomographic (CT) scan showed complete thrombosis of the superior sagittal sinus, confirmed by magnetic resonance angiography and associated with a right frontal hemorrhagic infarction. Systematic screening for thrombophilia revealed homocystinuria linked to cystathionine β-synthase deficiency with underlying compound heterozygosity. The evolution was favorable after anticoagulant therapy, specific diet, and vitamin supplementation. This case is of interest because of the unusual clinical presentation as a pediatric cerebral sinovenous thrombosis. Furthermore, homocystinuria is rarely revealed by cerebral sinovenous thrombosis at the onset of the disease and should systematically be ruled out in pediatric stroke.

Brain neoplasms and coagulation-lessons from heterogeneity

The coagulation system constitutes an important facet of the unique vascular microenvironment in which primary and metastatic brain tumors evolve and progress. While brain tumor cells express tissue factor (TF) and other effectors of the coagulation system (coagulome), their propensity to induce local and peripheral thrombosis is highly diverse, most dramatic in the case of glioblastoma multiforme (GBM), and less obvious in pediatric tumors. While the immediate medical needs often frame the discussion on current clinical challenges, the coagulation pathway may contribute to brain tumor progression through subtle, context-dependent, and non-coagulant effects, such as induction of inflammation, angiogenesis, or by responding to iatrogenic insults (e.g. surgery). In this regard, the emerging molecular diversity of brain tumor suptypes (e.g. in glioma and medulloblastoma) highlights the link between oncogenic pathways and the tumor repertoire of coagulation system regulators (coagulome). This relationship may influence the mechanisms of spontaneous and therapeutically provoked tumor cell interactions with the coagulation system as a whole. Indeed, oncogenes (EGFR, MET) and tumor suppressors (PTEN, TP53) may alter the expression, activity, and vesicular release of tissue factor (TF), and cause other changes. Conversely, the coagulant microenvironment may also influence the molecular evolution of brain tumor cells through selective and instructive cues. We suggest that effective targeting of the coagulation system in brain tumors should be explored through molecular stratification, stage-specific analysis, and more personalized approaches including thromboprophylaxis and adjuvant treatment aimed at improvement of patient survival.

Alterations in the Coagulation System during Major Visceral Surgery in Children

Purpose. The description of the alterations in the hemostatic system in children undergoing abdominal surgery is sparse. Enhanced clinical outcomes for previously untreatable conditions have led to an increased incidence of venous thromboembolic complications. Alterations in children's coagulation system during major abdominal operations compared to minor procedures were examined. Methods. Children (0–12 years) undergoing either laparotomy, thoracotomy, or minor surgery were included. Participants were divided into two groups: group 1 was open laparotomy including operations for solid abdominal tumours and thoracotomy, while group 2 was minor surgery. Activated partial thromboplastin time (aPTT), D-dimer, INR, and fibrinogen were measured. Results. Both groups had a shorter aPTT, higher INR, and lower fibrinogen concentrations after the operation, while D-dimer was unaltered. The changes were, however, discrete and probably not clinically significant. On day 3, all parameters except aPTT in group 1 (not measured in group 2) indicated a continuous coagulation activity. Conclusion. The tendency for coagulation activity altered based on the length and degree of surgery. A continuously altered activity was observed compatible with the reported increased risk of venous thromboembolism at day 3. However, before introducing thromboprophylaxis guidelines larger series of multicentre studies are needed.

Do children with central venous line (CVL) dysfunction have increased risk of symptomatic thromboembolism compared to those without CVL-dysfunction, while on cancer therapy?

Background

Thromboembolism (TE) and infection are two common complications of central venous line (CVL). Thrombotic CVL-dysfunction is a common, yet less studied, complication of CVL. Two retrospective studies have reported significant association of CVL-dysfunction and TE. Recent studies indicate association of CVL-related small clot with infection. Infection is the most common cause of non-cancer related mortality in children with cancer. We and others have shown reduced overall survival (OS) in children with cancer and CVL-dysfunction compared to those without CVL-dysfunction. Despite these observations, to date there are no prospective studies to evaluate the clinical significance of CVL-dysfunction and it’s impact on the development of TE, infection, or outcome of children with cancer.

Study design

This is a prospective, analytical cohort study conducted at five tertiary care pediatric oncology centers in Ontario. Children (≤ 18 years of age) with non-central nervous system cancers and CVL will be eligible for the study. Primary outcome measure is symptomatic TE and secondary outcomes are infection, recurrence of cancer and death due to any cause. Data will be analyzed using regression analyses.

Discussion

The overall objective is to delineate the relationship between CVL-dysfunction, infection and TE. The primary aim is to evaluate the role of CVL-dysfunction as a predictor of symptomatic TE in children with cancer. We hypothesize that children with CVL-dysfunction have activation of the coagulation system resulting in an increased risk of symptomatic TE. The secondary aims are to study the impact of CVL-dysfunction on the rate of infection and the survival [OS and event free survival (EFS)] of children with cancer. We postulate that patients with CVL-dysfunction have an occult CVL-related clot which acts as a microbial focus with resultant increased risk of infection. Further, CVL-dysfunction by itself or in combination with associated complications may cause therapy delays resulting in adverse outcome.

This study will help to identify children at high risk for TE and infection. Based on the study results, we will design randomized controlled trials of prophylactic anticoagulant therapy to reduce the incidence of TE and infection. This in turn will help to improve the outcome in children with cancer.

Central venous line dysfunction is an independent predictor of poor survival in children with cancer

Central venous line (CVL) dysfunction (mainly from thrombotic occlusion) is a frequent, but relatively less-studied complication compared with infection and thromboembolism (TE). In adults with cancer, TE results in poor outcome. We evaluated the impact of CVL-dysfunction and TE on overall survival (OS) and event-free survival (EFS) in children with noncentral nervous system cancer (n=358). CVL-dysfunction was defined as persistent or recurrent difficulty of blood draw and/or infusion. Event was defined as cancer relapse, second malignancy, or death due to any cause. OS and EFS were estimated using Kaplan-Meier method and survival curves compared using log-rank test. Hazard ratios (HR) were calculated using the Weibull regression model. Diagnosis of TE (n=43, 12%) had no effect on the OS and EFS. Children with CVL-dysfunction (n=74, 21%) had shorter 5- and 10-year EFS compared with children without CVL-dysfunction (P=0.029 and P=0.027). Multiple regression analyses, adjusting for age, sex, diagnostic era, TE, and cancer type identified CVL-dysfunction as an independent determinant of 5-year OS (HR 1.87; 95% confidence interval, 1.02-3.42; P=0.043) and EFS (HR 1.96; 95% confidence interval, 1.23-3.41; P=0.018). Although the etiology of adverse impact of CVL-dysfunction on survival is unknown, its prevention and prompt treatment may improve outcome from cancer in children. Further prospective studies are recommended.

Venous thromboembolism and adolescent and young adult oncology inpatients in US children's hospitals, 2001 to 2008

OBJECTIVES

To determine the frequency of venous thromboembolism (VTE) in the adolescent and young adult oncology population and the effects of age and cancer type on VTE, and to characterize adolescent and young adult oncology admissions at US children's hospitals.

STUDY DESIGN

We extracted data on oncology patients 15 to 24 years of age who were discharged from 35 hospitals in the Pediatric Hospital Information System (PHIS) between 2001 and 2008.

RESULTS

Of 9721 unique patients, VTE occurred in 511 (5.3%). An elevated OR of VTE occurred in patients 18 to 20 and 21 to 24 years of age (OR, 1.65; 95% CI, 1.36-2.00 and OR, 1.67; 95% CI, 1.21-2.32, respectively) compared with that in patients 15 to 17 years old. Patients with leukemia (OR, 5.53; 95% CI, 3.63-8.42) and bone/soft tissue sarcomas (OR, 4.32; 95% CI, 2.80-6.69) had a higher risk of VTE compared with patients with brain tumors. The number of adolescent and young adult oncology admissions to pediatric hospitals increased 31.9%, from 5409 admissions in 2001 to 7134 admissions in 2008.

CONCLUSIONS

Adolescent and young adult oncology patients, a growing population at pediatric hospitals, experience VTE as a common complication. Pediatricians should implement adolescent and young adult-specific studies to develop a standardized approach to preventing this adverse event.

Thrombotic disease in critically ill children

OBJECTIVES

To summarize a) epidemiology of arterial and venous thromboembolism, pulmonary embolism, and deep venous thrombosis in children; b) the risk factors for thrombosis in the pediatric intensive care unit; c) diagnostic techniques for arterial/venous thromboembolism; and d) the current recommendations for management and prevention of thromboembolic disease in critically ill children.

DATA SOURCE

Literature review, using National Library of Medicine PubMed and the following terms: arterial, venous thromboembolism; deep venous thrombosis; pulmonary embolism; thrombosis; as well as citations of interest from these articles.

STUDY SELECTION

Both pediatric and adult literature addressing thrombotic disease were reviewed.

DATA EXTRACTION AND SYNTHESIS

Articles were chosen for more extensive discussion when containing prospective studies, guidelines for practice, or data in critically ill patients. When data in children were unavailable, applicable data in adults were referenced. Due to the paucity of data in critically ill children, available adult and pediatric data were combined with institutional experience to provide suggestions for current practice and future inquiry.

CONCLUSIONS

Increasing awareness regarding the recognition and current approaches to management and prevention of thromboembolic disease in children is needed among pediatric intensivists, so outcome of these life-threatening processes might be improved.

Thrombosis in the pediatric population

Whereas thrombotic events in critically ill children do not occur as commonly as in adults, they are being recognized with increasing frequency in the pediatric intensive care unit. The reasons for this are not clear but likely include an increased awareness of the problem and the ability to make a diagnosis using relatively noninvasive tests. In this section, I attempt to define the extent of the problem, summarize and discuss the relevant literature (pointing out where published experience in the pediatric population differs from that in adult patients), and suggest some guidelines regarding thrombophilia treatment and the management of thrombotic events.

Venous thromboembolism in malignant gliomas

Malignant gliomas are associated with a very high risk of venous thromboembolism (VTE). While many clinical risk factors have previously been described in brain tumor patients, the risk of VTE associated with newer anti-angiogenic therapies such as bevacizumab in these patients remains unclear. When VTE occurs in this patient population, concern regarding the potential for intracranial hemorrhage complicates management decisions regarding anticoagulation, and these patients have a worse prognosis than their VTE-free counterparts. Risk stratification models identifying patients at high risk of developing VTE along with predictive plasma biomarkers may guide the selection of eligible patients for primary prevention with pharmacologic thromboprophylaxis. Recent studies exploring disordered coagulation, such as increased expression of tissue factor (TF), and tumorigenic molecular signaling may help to explain the increased risk of VTE in patients with malignant gliomas.

Epidemiology and clinical risk factors predisposing to thromboembolism in children with cancer

PURPOSE

The prevalence and risk factors for thromboembolism (TE) in children with cancer are largely unknown. This retrospective cohort study aims to determine the epidemiology of TE and to identify potential risk factors for TE in children with cancer.

METHODS

We used logistic regression to determine the association of age (<10 years vs. > or =10 years), gender, type of cancer, presence or absence of intra-thoracic disease (mediastinal mass or any primary or metastatic pulmonary disease), type of central venous line (CVL) and CVL-dysfunction (difficulty of blood draw, infusion or documented CVL infection) on the risk of developing TE.

RESULTS

Fifty-seven of 726 patients [7.9%; 95% confidence intervals (CI); 6.0,10.0] developed TE; children with brain tumors (n = 201) had significantly lower prevalence of TE (0.5%; P < 0.001). Older patients had increased risk of developing TE compared to younger patients [Odds ratios (OR) 1.8; 95% CI; 1.0,3.2; P = 0.036]. Children with acute lymphoblastic leukemia (ALL) (OR 4.6; 95% CI; 1.8, 12.3; P = 0.002), lymphoma (OR 3.8; 95% CI; 1.3, 11.1; P = 0.016), and sarcoma (OR 4.3; 95% CI; 1.4, 13.3; P = 0.012) had an increased risk of TE. Subgroup analyses showed that patients with CVL-dysfunction and intra-thoracic disease had a higher prevalence of TE compared to those without CVL-dysfunction (22.8% vs. 8.8%; 95% CI; 4.0, 24.3; P = 0.006) and intra-thoracic disease (18.0% vs. 6.1%; 95% CI; 2.4, 21.4; P = 0.02).

CONCLUSIONS

TE is common in children with cancer. Age and type of cancer are independent risk factors for TE in children with non-CNS cancers. CVL-dysfunction and intra-thoracic disease are significantly associated with the diagnosis of TE.

Postoperative venous thromboembolism rates vary significantly after different types of major abdominal operations

BACKGROUND

Venous thrombolism (VTE) is a significant cause of morbidity for surgical patients. Comparative risk across major procedures is unknown.

METHODS

Retrospective analysis of the Nationwide Inpatient Sample (2001-2005) was conducted. Eight surgeries were identified: bariatric surgery, colorectal surgery, esophagectomy, gastrectomy, hepatectomy, nephrectomy, pancreatectomy, splenectomy. Age < 18, patients with multiple major surgeries, and those admitted for treatment of VTE were excluded. Primary outcome was occurrence of VTE. Independent variables included age, gender, race, Charlson score, hospital teaching status, elective procedures, cancer/metastasis, trauma, and year.

RESULTS

Patients, 375,748, were identified, 5,773 (1.54%) with VTE. Overall death rate was 3.97%, but 13.34% after VTE. Unadjusted rate (0.35%) and adjusted risk for VTE were lowest among bariatric patients. On multivariate analysis, highest risk for VTE was splenectomy (odds ratio 2.69, 95% CI 2.03-3.56). Odds ratio of in-hospital mortality following VTE was 1.84 (1.65-2.05), associated with excess stay of 10.88days and $9,612 excess charges, translating into $55 million/year nationwide.

CONCLUSION

Highest risk for VTE was associated with splenectomy, lowest risk with bariatric surgery. Since bariatric patients are known to have greater risk for this complication, these findings may reflect better awareness/prophylaxis. Further studies are necessary to quantify effect of best-practice guidelines on prevention of this costly complication.

Venous thrombosis in children with solid tumors

BACKGROUND

The prevalence of venous thrombosis (VT) in children with solid tumor and the role of different risk factors are not defined yet.

AIM

A cross-sectional observational study was conducted to evaluate the prevalence of both symptomatic and asymptomatic catheter-associated thrombosis events in children affected with different solid tumors.

METHODS

Patients with a solid tumor, admitted as day-care, were consecutively enrolled over a period of 10 months. All of them had a central venous line. Physical examination, D-dimer serum tests, and eco-color-Doppler ultrasonography were performed once at any time before catheter removal.

RESULTS

Forty-two patients (14 females and 28 males)-mean age 115 months-were evaluated. Five of the 42 patients (12%) had VT. In 4 of these, VT was catheter-related: 3 asymptomatic and 1 symptomatic. In the last patient, VT was clinically symptomatic and not catheter related. Patients with longer duration of catheter insertion presented with a higher rate of VT (P=0.05). Moreover, patients affected with neuroblastoma showed a higher rate of VT than the others with different solid tumors (P<0.05).

CONCLUSIONS

VT was visualized by echo-color-Doppler ultrasonography in 12% of the patients; it was asymptomatic in 7%. In our small series, VT was related to neuroblastoma disease and a longer duration of catheter insertion. Prospective and multicentric studies are required to select risk factors for VT in children with solid tumors.

Medical management of brain tumor patients

Brain tumors can present challenging medical problems. Seizures, peritumoral edema, venous thromboembolism, fatigue, and cognitive dysfunction can complicate the treatment of patients who have primary or metastatic brain tumors. Effective medical management results in decreased morbidity and mortality and improved quality of life for affected patients.

Thromboembolic Events in Children and Young Adults With Pediatric Sarcoma

Purpose

Adults with malignancy are at increased risk for venous thromboembolic events (TEs). However, data in children and young adults with cancer are limited.

Patients and Methods

To determine the risk and clinical features of TEs in children and young adults with sarcoma, we reviewed records on 122 consecutive patients with sarcoma treated from October 1980 to July 2002.

Results

Twenty-three TEs were diagnosed in 19 of 122 (16%; 95% CI, 10% to 23%) patients. Prevalence by diagnosis was Ewing sarcoma, eight of 61 (13%); osteosarcoma, two of 20 (10%); rhabdomyosarcoma, four of 26 (15%); and other sarcomas, five of 15 (33%). TEs developed in 23% of patients with metastases at presentation versus 10% with localized disease (odds ratio, 2.59; 95% CI, 0.9 to 7.1; P < .06). Fifty-three percent of patients with thrombosis had a clot at presentation. A lupus anticoagulant was detected in four of five evaluated patients. There was a single fatality due to pulmonary embolism. Patients who were diagnosed with cancer after 1993 had a higher rate of TE (7% v 23%; P < .015). Of the 23 events, 43% were asymptomatic. Main sites of thromboses were deep veins of the extremities (10 of 23; 43%), pulmonary embolism (five of 23; 22%), and the inferior vena cava (four of 23; 17%). TEs were associated with tumor compression in eight of 23 (35%) and with venous catheters in three of 23 (13%).

Conclusion

Thromboembolism is common in pediatric patients with sarcomas. Thromboses are detected frequently around the time of oncologic presentation, may be asymptomatic, and seem to be associated with a higher disease burden. Children and young adults with sarcoma should be monitored closely for thrombosis.

Medical management of patients with brain tumors

The most common medical problems in brain tumor patients include the management of seizures, peritumoral edema, medication side effects, venous thromboembolism (VTE), fatigue and cognitive dysfunction. Despite their importance, there are relatively few studies specifically addressing these issues. There is increasing evidence that brain tumor patients who have not had a seizure do not benefit from prophylactic antiepileptic medications. Patients on corticosteroids are at greater risk of Pneumocystis jerovecii pneumonia and may benefit from prophylactic therapy. There is also growing evidence suggesting that anticoagulation may be more effective than inferior vena cava IVC) filtration devices for treating VTE in brain tumor patients and the risk of hemorrhage with anticoagulation is relatively small. Low-molecular weight heparin may be more effective than coumadin. Medications such as modafinil and methylphenidate have assumed an increasing role in the treatment of fatigue, while donepezil and memantine may be helpful with memory loss.

Thrombosis in children with malignancy

PURPOSE OF REVIEW

The association between thrombosis and malignancy in adults is well known. Children are now surviving malignancies that previously resulted in mortality. Complications, however, occur including thrombosis that result in mortality and morbidity. This review will explore the association in children and discuss the epidemiology and evidence-based diagnosis and treatment of thrombosis in this cohort.

RECENT FINDINGS

Thrombin is an important link between malignancy, metastases, and inflammation. The accurate diagnosis of thrombosis in the upper venous system is directly related to the diagnostic technique used. Antithrombotic treatment is challenging owing to higher risks of bleeding, for example, decreased platelet counts, tiffelitis, large vascular tumor, etc.

SUMMARY

Thrombosis and malignancy are associated in children. Properly designed studies are urgently required to further define the epidemiology of thrombosis in different malignancies and to find the best way to diagnose and treat thrombosis in children.

Thromboembolic complications in children with cancer

Thrombosis is a significant problem in patients with cancer. The impact of thromboembolism in association with childhood cancer is not clearly defined. Similarly the information of prevention and management of thromboembolic events in children receiving cancer-therapy is limited. This review aims to examine current knowledge regarding the epidemiology, pathophysiology and management of thrombosis in association with cancer in children.

Thrombosis in infants and children

During the last decade much progress has been made toward better understanding of the underlying reasons causing thromboembolism in children. A considerable number of acquired and hereditary thrombotic risk factors have been identified which may also have an impact on therapeutic decisions and prognosis concerning outcome and the risk of a second event. However, indications for therapeutic interventions, such as thrombolysis and prophylactic anticoagulation with respect to the different clinical conditions and their combination with other risk factors, are not yet well defined. The following article describes the causes, clinical presentation and management of thrombosis in neonates, infants and older children, focusing on the clinically most relevant conditions.