Thromboembolic complications in children with cancer

Thrombotic Complications in Pediatric Cancer

Thromboembolism (TE) complicates the course of pediatric cancer in a considerable number of cases. Cancer-related TE is attributed to an interaction of the underlying malignancy, the effects of therapy, and a possible thrombophilia predisposition. More specifically, recognized risk factors include a very young age and adolescence, non-O blood group, type and site of cancer, inherited thrombophilia, presence of central venous catheter, and type of chemotherapy. TE in children with cancer most commonly occurs in their extremities. In the absence of evidence-based guidelines for the management of thrombotic complications in pediatric oncology patients, TE management follows general recommendations for the management of pediatric TEs. Given the limitations of conventional anticoagulant therapy, direct oral anticoagulants could provide an alternative; however, their safety and efficacy in children with cancer remain to be seen. As for thromboprophylaxis, numerous studies have been conducted, albeit with conflicting results. Although the survival of pediatric oncology patients has significantly improved in recent years, morbidity due to cancer-related TE remains, underlying the need for large multicenter trials investigating both TE management with currently available agents and primary prevention.

The association of mediastinal mass in the formation of thrombi in pediatric patients with non-lymphoblastic lymphomas

BACKGROUND

Children diagnosed with cancer are at a significantly higher risk of developing a thrombotic event (TE) compared with the general population. The rarity of these events makes it difficult to discern the specific risk factors; however, age, sex, presence of central venous lines, inherited thrombophilia, and mediastinal mass may play a role. The primary aim of this study is to identify prognostic characteristics of children diagnosed with non-lymphoblastic lymphomas associated with a greater risk of developing a TE early on in their disease, with an increased focus on mediastinal mass characteristics.

METHODS

Retrospective chart review of pediatric patients diagnosed with non-lymphoblastic lymphoma between 2004 and 2014 at St. Jude Children's Research Hospital.

RESULTS

TE occurred in 8.5% (n = 28/330) of individuals at a median of 21 days from the diagnosis of a non-lymphoblastic lymphoma, with 60% of TEs occurring within 30 days of diagnosis. Of the variables evaluated, only presence of a peripherally inserted central catheter (odds ratio [OR]: 3.14 [95% CI: 1.24-7.98; P = 0.02]) and degree of superior vena cava (SVC) compression of > 25% increased the odds of developing a TE (OR: 2.2 [95% CI: 1.01-4.93; P = 0.048]).

CONCLUSION

Pediatric patients with non-lymphoblastic lymphoma are at increased risk of developing TEs. In contrast to previous studies, the presence of a mediastinal mass alone was not associated with a higher risk of TE, but individuals with a mediastinal mass with 25% or greater degree of SVC compression were more likely to develop a TE. This finding highlights a high-risk group of children who may benefit from prophylactic anticoagulation.

THROMBOTECT - a randomized study comparing low molecular weight heparin, antithrombin and unfractionated heparin for thromboprophylaxis during induction therapy of acute lymphoblastic leukemia in children and adolescents

Thromboembolism is a serious complication of induction therapy for childhood acute lymphoblastic leukemia. We prospectively compared the efficacy and safety of antithrombotic interventions in the consecutive leukemia trials ALL-BFM 2000 and AIEOP-BFM ALL 2009. Patients with newly diagnosed acute lymphoblastic leukemia (n=949, age 1 to 18 years) were randomized to receive low-dose unfractionated heparin, prophylactic low molecular weight heparin (enoxaparin) or activity-adapted antithrombin throughout induction therapy. The primary objective of the study was to determine whether enoxaparin or antithrombin reduces the incidence of thromboembolism as compared to unfractionated heparin. The principal safety outcome was hemorrhage; leukemia outcome was a secondary endpoint. Thromboembolism occurred in 42 patients (4.4%). Patients assigned to unfractionated heparin had a higher risk of thromboembolism (8.0%) compared with those randomized to enoxaparin (3.5%; P=0.011) or antithrombin (1.9%; P<0.001). The proportion of patients who refused antithrombotic treatment as allocated was 3% in the unfractionated heparin or antithrombin arms, and 33% in the enoxaparin arm. Major hemorrhage occurred in eight patients (no differences between the groups). The 5-year event-free survival was 80.9±2.2% among patients assigned to antithrombin compared to 85.9±2.0% in the unfractionated heparin group (P=0.06), and 86.2±2.0% in the enoxaparin group (P=0.10). In conclusion, prophylactic use of antithrombin or enoxaparin significantly reduced thromboembolism. Despite the considerable number of patients rejecting the assigned treatment with subcutaneous injections, the result remains unambiguous. Thromboprophylaxis - for the present time primarily with enoxaparin - can be recommended for children and adolescents with acute lymphoblastic leukemia during induction therapy. Whether and how antithrombin may affect leukemia outcome remains to be determined.

[Thromboembolic disease in pediatric oncology]

The survival rate of children with cancer is now close to 80 %, as a result of continuous improvement in diagnostic and treatment procedures. Prevention and treatment of treatment-associated complications is now a major challenge. Thromboembolic venous disease, due to multifactorial pathogenesis, is a frequent complication (up to 40 % asymptomatic thrombosis in children with cancer), responsible for significant morbidity. Predominantly in children with acute lymphoblastic leukemia, lymphoma, or sarcoma, thromboembolic disease justifies primary prophylaxis in certain populations at risk, whether genetic or environmental. The curative treatment, well codified, is based on the administration of low-molecular-weight heparin. In the absence of robust pediatric prospective studies, this article proposes a concise decision tree summarizing the preventive and curative strategy.

Epidemiology of venous thrombosis in children with cancer

There has been an extensive body of research focusing on the epidemiology of thrombosis in adult cancer populations; however, there is significantly less knowledge about thrombosis in paediatric cancer populations. Thrombosis is diagnosed with increasing frequency in children being treated for cancer, and there is an urgent need to increase our understanding of the epidemiology of thrombosis in this population. Currently, there are no guidelines for identification of high-risk groups, prophylaxis or management of thrombotic complications in paediatric cancer patients. We reviewed the available literature regarding the epidemiology, mechanisms, risk factors, prophylaxis and outcomes of thrombosis in children with cancer and identified areas that require further research. The reported incidence of symptomatic venous thromboembolism (VTE) in children with cancer ranges between 2.1% and 16%, while the incidence of asymptomatic events is approximately 40%. Approximately 30% of VTE in this population is associated with central venous lines (CVL). The most common location of VTE is upper and lower extremity deep venous thrombosis (43 to 50% of events, respectively), while 50% of events in ALL patients occur in the central nervous system. Key characteristics that increase the risk of thrombosis include the type of cancer, age of the patient, the presence of a CVL, presence of pulmonary/intra thoracic disease, as well as the type of chemotherapy. Outcomes for paediatric cancer patients with VTE include post-thrombotic syndrome, pulmonary embolism, recurrent thromboembolism, destruction of upper venous system and death. Prospective studies aimed at enabling risk stratification of patients are required to facilitate development of paediatric specific recommendations related to thromboprophylaxis in this population.

Safe Use of Low-Molecular-weight Heparin in Pediatric Acute Lymphoblastic Leukemia and Lymphoma Around Lumbar Punctures

Children with acute lymphoblastic leukemia or lymphoma (ALL) undergo multiple lumbar punctures (LPs) and frequently require low-molecular-weight heparin (LMWH) for thromboembolic complications. We evaluated if withholding LMWH 24 hours before and after LPs prevented bleeding complications. Children (n=133) with ALL from who were: (1) treated at St. Jude Children's Research Hospital, (2) received LMWH (2×/day of ~1 mg/kg) between January 2004 until December 2012, and (3) underwent a LP were analyzed. Spinal hematoma was defined as a clinical suspicion leading to diagnostic imaging. Traumatic LP was defined as ≥10 red blood cells per microliter of cerebrospinal fluid. In 1708 LPs, no hematomas occurred. For each child treated with LMWH, the probability of experiencing a spinal hematoma during the entire ALL treatment course was 0% (95% confidence interval [CI], 0.0%-2.7%), and in each LP, assuming no intrapatient correlation, the probability of spinal hematoma was 0% (95% CI, 0.0%-0.2%). Traumatic LPs were more common when performed when children were not receiving LMWH therapy (odds ratio [OR], 1.5; 95% CI, 1.1-2.2) which may be explained by clinician optimization of known risk factors for traumatic cerebrospinal fluid before the procedures. Withholding LMWH for 24 hours before and after LPs in children being treated for ALL is safe.

USE OF WARFARIN IN PEDIATRICS: CLINICAL AND PHARMACOLOGICAL CHARACTERISTICS

Objective:

To describe how children respond to oral anticoagulation with warfarin, verifying the influence of age, clinical condition, route of administration of warfarin and use of total parenteral nutrition (TPN), as well as to describe risk factors for the occurrence of thrombotic events (TE) in childhood.

Methods:

A retrospective descriptive study including all patients ≤18 years old for whom warfarin was prescribed in a university hospital. Patients were divided according to clinical condition, age, route of medication administration and use of TPN. Data was collected from the patients’ medical records and the analysis considered the risk factors for TE already described in the literature, the time and the dose required in order to reach the first International Normalized Ratio (INR) in the target and the adverse events in this period. After reaching the INR, the maintenance of anticoagulation was verified by the prescribed dose and INR tests.

Results:

Twenty-nine patients were included in the study. The major risk factor for TE was the use of a central venous catheter in 89.6% of the patients. Patients with short bowel syndrome and total parenteral nutrition required significantly higher doses (p≤0.05) to achieve and maintain the INR in the target. Patients ≤1 year old needed longer periods and required an increased dose of anticoagulation and maintenance than older patients. The mean number of INR examinations below the target was 48.2% in the groups studied.

Conclusions:

The observed complexity of anticoagulant therapy reinforces the need to develop protocols that guide clinical practice.

Venous thrombosis in children and adolescents with Hodgkin lymphoma in Sweden

INTRODUCTION

Pediatric patients with Hodgkin lymphoma (HL) have several risk factors for venous thromboembolism (VTE). Although these patients are occasionally treated with thromboprophylaxis, no guidelines are implemented in Sweden. Scarce data from adult patients indicate an increased risk of VTE, but pediatric data is largely missing. Given the favorable overall survival of HL, there should reasonably be more focus on preventing complications.

MATERIALS AND METHODS

We conducted a retrospective cohort study, including all patients registered in the Childhood Cancer Registry under the age of 18years diagnosed with HL between January 2005 and December 2015 in Sweden.

RESULTS

Data was retrieved from the medical records of all 163 patients (100%) at six Swedish pediatric cancer centers. The incidence of VTE was 7.7% (symptomatic VTE 3.9%). The median follow-up was 3.4years (range 0.3-10.5). Only five patients (3.1%) were treated with thromboprophylaxis. All VTE events occurred in the older age category (11-17years) and all but one (92.7%) had a mediastinal mass. While the VTE did not significantly affect the treatment of HL, it caused increased morbidity and 2/12 developed a post-thrombotic syndrome. No significant risk factors for VTE were identified.

CONCLUSIONS

VTE is a relatively common complication of HL and its treatment, causing increased acute and long-term morbidity. However, due to limited number of events we could not demonstrate risk-factors for VTE that would identify patients who might benefit from thromboprophylaxis.

Assessment of the outcomes associated with periprocedural anticoagulation management in children with acute lymphoblastic leukemia

OBJECTIVE

To report the outcomes of an institutional protocol for periprocedural anticoagulant (AC) management in children with acute lymphoblastic leukemia (ALL).

STUDY DESIGN

Children being treated for ALL who received full-dose (therapeutic) anticoagulation before undergoing at least 1 lumbar puncture (LP) were included in this retrospective cohort study. The main outcome was the risk of traumatic LP; exploratory analysis included the risks of symptomatic spinal hematoma and progression/recurrence of the thrombotic event. Analyses were conducted using logistic regression analysis with a generalized estimating equation approach.

RESULTS

Twenty-two children with ALL receiving an AC underwent a total of 396 LPs. Although traumatic LP was associated with full-dose AC therapy in univariable analysis, a multiple logistic regression model controlling for other risk factors for traumatic LP showed that AC therapy was not significantly associated with the risk of traumatic LP when the ACs were held as per the institutional protocol. No patient developed symptomatic spinal hematoma. Exploratory analysis revealed that AC dose, a likely marker of thrombus burden, was significantly associated with progression/recurrence of the thrombotic event in univariable analysis.

CONCLUSION

In our cohort, recent AC therapy was not statistically associated with an increased risk of bleeding after LP when following a specific protocol for periprocedural AC management. The risk associated with the progression/recurrence of thromboembolic events requires further evaluation.

Current practice managements regarding thromboembolic prophylaxis within the pediatric sarcoma patient population

OBJECTIVE

Children with cancer are approximately 600 times more likely to develop thromboses than the general pediatric population. Current management strategies for children have been extrapolated from adult studies and prophylaxis guidelines remain controversial. The purpose of this study is to survey the current thromboembolic prophylaxis practice methods of physicians treating pediatric sarcoma patients.

METHODS

Physicians involved in the care of sarcoma patients were surveyed using a 5-question survey designed to evaluate current clinical practices.

RESULTS

Of 107 responding physicians, 67 identified themselves as involved in the treatment of pediatric sarcoma patients. The providers most likely to use any form of deep vein thrombosis prophylaxis were orthopedic surgeons (60%), followed by general surgeons (45%), pediatric oncologists (30%), and medical oncologists (25%). Of the providers polled, 48% use mechanical forms, 20% use chemical forms, and 31% use a combination.

CONCLUSIONS

Currently, there is a lack of consensus regarding thromboembolic prophylaxis for pediatric sarcoma patients.

Successful treatment of acute lymphoblastic leukemia in a child with trisomy 21 and complex congenital heart disease with mechanical prosthetic valve

A 10-year-old girl with trisomy 21 and complex congenital heart disease presented with acute lymphoblastic leukemia. Her chemotherapy required modifications due to poor baseline cardiac status and a mechanical prosthetic heart valve that was dependent on anticoagulation. We describe our management including the use of low-molecular-weight heparin as anticoagulation for a mechanical heart valve, the safe delivery of intrathecal chemotherapy included bridging with unfractionated heparin, and the use of fluoroscopic guidance to minimize the risk of bleeding. Adjustments were made to avoid anthracyclines. The child tolerated therapy well without complications and remains relapse free five years after diagnosis.

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.

Antithrombotic therapy in neonates and children: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

Neonates and children differ from adults in physiology, pharmacologic responses to drugs, epidemiology, and long-term consequences of thrombosis. This guideline addresses optimal strategies for the management of thrombosis in neonates and children.

METHODS

The methods of this guideline follow those described in the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines.

RESULTS

We suggest that where possible, pediatric hematologists with experience in thromboembolism manage pediatric patients with thromboembolism (Grade 2C). When this is not possible, we suggest a combination of a neonatologist/pediatrician and adult hematologist supported by consultation with an experienced pediatric hematologist (Grade 2C). We suggest that therapeutic unfractionated heparin in children is titrated to achieve a target anti-Xa range of 0.35 to 0.7 units/mL or an activated partial thromboplastin time range that correlates to this anti-Xa range or to a protamine titration range of 0.2 to 0.4 units/mL (Grade 2C). For neonates and children receiving either daily or bid therapeutic low-molecular-weight heparin, we suggest that the drug be monitored to a target range of 0.5 to 1.0 units/mL in a sample taken 4 to 6 h after subcutaneous injection or, alternatively, 0.5 to 0.8 units/mL in a sample taken 2 to 6 h after subcutaneous injection (Grade 2C).

CONCLUSIONS

The evidence supporting most recommendations for antithrombotic therapy in neonates and children remains weak. Studies addressing appropriate drug target ranges and monitoring requirements are urgently required in addition to site- and clinical situation-specific thrombosis management strategies.

Venous thrombosis in children: an emerging issue

More and more cases of venous thrombosis are diagnosed in children thanks to newer imaging modalities. Central venous catheters have become commonplace in the care of critically ill children and have contributed to the increased rate of thrombotic events. Lastly, children who develop life-threatening or chronic medical conditions are surviving longer because of advanced medical therapies; these intensive therapies can be complicated by events such as thrombosis. Over the last 10 years, specific guidelines for treating thrombosis in children have become available. Nevertheless, in many situations anticoagulant treatment is specially tailored to each individual patient's needs. Some new antithrombotic drugs which have undergone clinical testing in adults might be beneficial to paediatric patients with thromboembolic disorders; unfortunately, clinical data and reports on the use of these drugs in children, when available, are extremely limited. The aim of this review is to provide physicians with enough background information to be able to manage thrombosis in children. First, by helping them detect a thrombotic event in a child. Upon confirmation of the diagnosis, the physician will request the appropriate tests and will choose the best treatment on the basis of the guidelines and recommendations. Moreover, the paediatrician will have the information he or she needs to identify which children are at highest risk of acute thrombotic events and relevant long-term sequelae and, therefore, to decide on the appropriate prophylactic or pharmacologic strategy. Lastly, we would like to provide the paediatrician with information on future drugs with regard to the treatment and prophylaxis of thrombosis.

Cerebral venous sinus thrombosis in an adolescent with Ewing sarcoma

BACKGROUND

Although thromboembolic complications are common in adult patients with malignant diseases, cerebral venous sinus thrombosis has been rarely described in cancer afflicted pediatric and adolescent population.

CASE HISTORY

A 16-year-old adolescent girl referred for complaints of pain and swelling on her left leg. On physical examination, a solid tibial mass was discovered. After the diagnosis of Ewing sarcoma with a tru-cut biopsy, chemotherapy protocol consisting of cisplatin, ifosfamide, adriamycine, and vincristine was started. During the first course of the treatment, the patient expressed headache, diplopia, and ptosis. Contrast-enhanced magnetic resonance (MR) images and MR angiography showed superior sagittal and transverse sinus thromboses. After anticoagulant therapy, the thromboses disappeared within 1.5 months. She received her chemotherapy protocol with the anticoagulant prophylaxis. After a follow-up period of 12 months, she is still in a good neurological recovery without any sequel.

CONCLUSION

Children and adolescents with cancer should be monitored closely for thrombotic complications. We discuss this uncommon case to draw attention to the importance of early diagnosis and adequate treatment of intracranial thrombosis in childhood cancer, and we review the relevant literature.

Antithrombotic therapy in neonates and children: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This chapter about antithrombotic therapy in neonates and children is part of the Antithrombotic and Thrombolytic Therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs, and Grade 2 suggests that individual patient values may lead to different choices (for a full understanding of the grading, see Guyatt et al in this supplement, pages 123S-131S). In this chapter, many recommendations are based on extrapolation of adult data, and the reader is referred to the appropriate chapters relating to guidelines for adult populations. Within this chapter, the majority of recommendations are separate for neonates and children, reflecting the significant differences in epidemiology of thrombosis and safety and efficacy of therapy in these two populations. Among the key recommendations in this chapter are the following: In children with first episode of venous thromboembolism (VTE), we recommend anticoagulant therapy with either unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) [Grade 1B]. Dosing of IV UFH should prolong the activated partial thromboplastin time (aPTT) to a range that corresponds to an anti-factor Xa assay (anti-FXa) level of 0.35 to 0.7 U/mL, whereas LMWH should achieve an anti-FXa level of 0.5 to 1.0 U/mL 4 h after an injection for twice-daily dosing. In neonates with first VTE, we suggest either anticoagulation or supportive care with radiologic monitoring and subsequent anticoagulation if extension of the thrombosis occurs during supportive care (Grade 2C). We recommend against the use of routine systemic thromboprophylaxis for children with central venous lines (Grade 1B). For children with cerebral sinovenous thrombosis (CSVT) without significant intracranial hemorrhage (ICH), we recommend anticoagulation initially with UFH, or LMWH and subsequently with LMWH or vitamin K antagonists (VKAs) for a minimum of 3 months (Grade 1B). For children with non-sickle-cell disease-related acute arterial ischemic stroke (AIS), we recommend UFH or LMWH or aspirin (1 to 5 mg/kg/d) as initial therapy until dissection and embolic causes have been excluded (Grade 1B). For neonates with a first AIS, in the absence of a documented ongoing cardioembolic source, we recommend against anticoagulation or aspirin therapy (Grade 1B).

Thromboembolism in children with sarcoma

BACKGROUND

Thromboembolism (TE) is a common complication and cause of death in adults with cancer. Cancer has been identified as a major risk factor in children with TE. However, the information regarding the epidemiology of TE in children with cancer, especially in association with childhood solid tumors, is scant.

OBJECTIVE

To define the prevalence and epidemiology of TE in children with sarcoma.

PROCEDURE

Hospital records of children </=18 years of age with sarcoma diagnosed and treated at McMaster Children's Hospital during January 1990 to December 2005 were reviewed for demographic details, details of diagnosis and therapy for sarcoma, and details of diagnosis and management of TE. Statistical analysis was performed using Fisher's exact t-test.

RESULTS

Ten of 70 (14.3%; 95% CI; 7.1, 24.7) patients with sarcoma developed symptomatic TE. Patients with CVL-dysfunction (n = 9) were at significantly higher risk for symptomatic TE compared to those without CVL dysfunction (n = 61) (55.5 vs. 8.2%; P = 0.002, 95% CI; 14.2, 80.5). Patients with pulmonary disease (n = 23) had higher prevalence of TE compared to those without pulmonary disease (n = 47) (26 vs.8.5%; P = 0.07, 95% CI; -2.06, 37.2). Older patients, patients with metastatic disease and those with Ewing sarcoma had higher prevalence of TE.

CONCLUSIONS

TE is a significant complication in children with sarcoma. Over 50% of patients with CVL dysfunction had symptomatic TE; such patients may warrant careful evaluation for associated TE. Large prospective studies are needed to define the epidemiology and identify risk factors predisposing to TE in children with sarcoma.

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.

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.