Bleeding and thrombosis in children with acute lymphoblastic leukaemia, treated according to the ALL-BFM-90 protocol

Thrombosis Complications in Pediatric Acute Lymphoblastic Leukemia: Risk Factors, Management, and Prevention: Is There Any Role for Pharmacologic Prophylaxis?

Pediatric acute lymphoblastic leukemia (ALL) has achieved close to 90% cure rates through extensive collaborative and integrative molecular research, clinical studies, and advances in supportive care. Despite this high achievement, venous thromboembolic complications (VTE) remain one of the most common and potentially preventable therapy-associated adverse events in ALL. The majority of thromboses events involve the upper central venous system which is related to the use and location of central venous catheters (CVC). The reported rates of symptomatic and asymptomatic CVC-related VTE range from 2.6 to 36.7% and 5.9 to 43%, respectively. Thrombosis can negatively impact not only disease-free survival [e.g., therapy delays and/or interruption, omission of chemotherapy agents (e.g., asparaginase therapy)] but also can result in long-term adverse effects that can impair the quality of life of ALL survivors (e.g., post-thrombotic syndrome, central nervous system (CNS)-thrombosis related complications: seizures, neurocognitive deficits). In this review, will discuss thrombosis pathophysiology in pediatric ALL, risk factors, treatment, and prevention strategies. In addition, the recently published clinical efficacy and safety of direct oral anticoagulants (DOACs) use in thrombosis treatment, and their potential role in primary/secondary thrombosis prevention in pediatric patients with ALL will be discussed. Future clinical trials involving the use of these novel oral anticoagulants should be studied in ALL not only for primary thrombosis prevention but also in the treatment of thrombosis and its secondary prevention. These future research findings could potentially extrapolate to VTE prevention strategies in other pediatric cancer diagnoses and children considered at high risk for VTE.

Cerebral Sinus Venous Thrombosis in Indian Pediatric Patients With Acute Lymphoblastic Leukemia: Incidence, Risk Factors, and Outcome

Cerebral sinus venous Thrombosis (CSVT) is a rare complication of acute lymphoblastic leukemia (ALL) treatment, with an incidence rate ranging from 1.1% to 2.9%. Steroids and L-asparaginase (LASP) are the major risk factors.

The aim of this study was to find the incidence rate and risk factors for CSVT in our patients. Ninety-two pediatric ALL diagnosed and treated with ALL-Berlin–Frankfurt–Munster-95 protocol over a period of 5 years (2013–2017) were the subject of the study. Six (6.5%) patients developed CSVT during their therapy and were further analyzed.

Six (five males and one female) patients had a CSVT event. The mean age at presentation was 13.5 ± 4.1 years. CSVT event occurred during the induction/re-induction phase of chemotherapy. The superior sagittal sinus was the most frequent site of thrombosis. The timing of CSVT was related to using of LASP and steroids. High-risk disease was associated with an increased risk of thrombosis. Infection and dehydration were other important risk factors. No association was observed between the risk of CSVT and age, sex, immunophenotype, and white blood cell count. All the patients were treated with low-molecular-weight heparin and one patient developed heparin-induced thrombocytopenia. No death occurred due to CSVT.

The Incidence of CSVT was 6.5% in our study which is significantly high but comparable with studies from other Asian countries. It is, therefore, important to be vigilant for the detection of CSVT during treatment of ALL and initiate the appropriate treatment to prevent adverse events.

Fifteen-minute consultation: Initial management of suspected acute leukaemia by non-specialists

Leukaemia is the most common cancer of childhood. Most children with a new diagnosis of leukaemia are clinically stable at initial presentation. However, there are a number of life-threatening complications that have to be considered and monitored for. These complications include sepsis, tumour lysis syndrome, mediastinal masses, bleeding and pain. The aim of this article is to equip the general paediatrician with a framework for managing children with suspected leukaemia, prior to transfer to the primary treatment centre. The presentation, diagnosis and definitive treatment of acute leukaemia is not in the remit of this article.

Analysis of apoptotic, platelet-derived, endothelial-derived, and tissue factor-positive microparticles of children with acute lymphoblastic leukemia during induction therapy

OBJECTIVES

Thromboembolism is one of the most common complications during induction therapy of pediatric acute lymphoblastic leukemia (ALL). Procoagulant microparticles in the circulation may cause thromboembolic events. The aim of our study was to determine the levels of apoptotic, platelet-derived, endothelial-derived, and tissue factor-positive microparticles of children with ALL at diagnosis and during induction therapy.

METHODS

Sixteen precursor B-cell ALL cases and 30 healthy children between 1 and 18 years of age were included. Microparticle levels were analyzed from peripheral blood samples at initial diagnosis, on days 12 and 13 (before and after the first L-asparaginase administration), and on day 33 of ALL-BFM 2000 treatment protocol. Microparticle levels were analyzed by using flow cytometry.

RESULTS

At initial diagnosis, platelet, endothelial-derived, and tissue factor-positive microparticle levels were significantly high in children with ALL. They increased significantly after prednisone and L-asparaginase administration. Apoptotic microparticle levels were not elevated at diagnosis, but remained high during all induction therapy period. None of the patients had evidence of thromboembolism during induction therapy.

CONCLUSION

Our study demonstrated that children with ALL have increased levels of apoptotic, platelet-derived, endothelial-derived, and tissue factor-positive microprticles during induction therapy. Further studies are needed in larger groups of patients in order to evaluate the risk of elevated microprticles for development of thromboembolism during induction therapy period in children with ALL.

Human Fibrinogen Concentrate and Fresh Frozen Plasma in the Management of Severe Acquired Hypofibrinogenemia in Children With Acute Lymphoblastic Leukemia: Results of a Retrospective Survey

OBJECTIVE OF THE STUDY

In this study we aimed to retrospectively evaluate how centers, belonging to the Associazione Italiana Ematologia e Oncologia Pediatrica (AIEOP), manage severe acquired hypofibrinogenemia in children with acute lymphoblastic leukemia, particularly evaluating the therapeutic role of human fibrinogen concentrate (HFC) and fresh frozen plasma (FFP).

METHODS

We conducted a survey among AIEOP centers; thereafter, we collected and analyzed data with regard to the treatment of episodes of severe acquired hypofibrinogenemia occurring during the induction and reinduction phases of the AIEOP-BFM ALL 2009 protocol.

RESULTS

In total, 15 of the 37 AIEOP centers invited to join the survey agreed to collect the data, with 10 and 5 centers declaring to react to severe acquired hypofibrinogenemia (<70 mg/dL) by administering HFC or FFP, respectively. Of the 150 episodes of severe hypofibrinogenemia occurring in 101 patients, 47.3% were treated with HFC and 52.7% with FFP, with a normalization of fibrinogen levels achieved in greater proportion and in a shorter amount of time in the HFC group as compared with the FFP group. None of the patients presented with bleeding or thrombosis during the observation period.

CONCLUSIONS

Even with the limitations of the retrospective nature of this study, HFC seems to be a safe and effective alternative to FFP for replacement therapy in case of severe hypofibrinogenemia in children with acute lymphoblastic leukemia.

Venous thromboembolism in a large cohort of children with acute lymphoblastic leukemia: Risk factors and effect on prognosis

BACKGROUND

Venous thromboembolism (VTE) is relatively common in children with acute lymphoblastic leukemia (ALL). Thrombotic risk factors in ALL are asparaginase and steroids. However, within the ALL populations treated on the same regimen, it is less clear which other risk factors play a role. Furthermore, few data are available on the effect of VTE on ALL outcomes.

METHODS

In 778 children (1-18 years) with newly diagnosed precursor-B-lineage or T-lineage ALL, treated in the Dutch Childhood Oncology Group (DCOG) ALL-10 protocol in the Netherlands (October 2004 to April 2013), we conducted a nested case control study with 59 VTE cases and 118 controls to identify risk factors for VTE.

RESULTS

Fifty-nine of 778 ALL patients developed VTE (7.6%), with cerebral venous sinus thrombosis (CVST) in 26 of 59 patients (44.1%). VTE occurred during induction treatment in 59.3% (n = 35) and in 40.7% (n = 24) during medium risk intensification. Conditional multivariable logistic regression analysis showed that age and ALL subtype were significantly associated with VTE (age ≥7 years: OR 2.72, 95% CI 1.33-5.57; ALL subtype T-ALL: OR 2.95, 95% CI 1.02-8.57). A multivariable Cox model showed no association between the occurrence of VTE and event free survival. In CVST patients, permanent disability was present in 34.6%.

CONCLUSION

Within this large pediatric ALL cohort, we demonstrated a high morbidity in CVST patients. Age ≥7 years at diagnosis and T-ALL subtype were the main risk factors for VTE, and should be considered in preventive strategies.

Thrombosis in pediatric patients with leukemia

Acute lymphoblastic leukemia (ALL) is the most common type of cancer diagnosed in children. It is reportedly the most common malignancy associated with thromboembolism in the pediatric age group. Over the last 2 decades, venous thromboembolism (VTE) has been increasingly diagnosed among pediatric ALL patients with an estimated incidence ranging from about 5% (for symptomatic cases) to about 30-70% (following sequential imaging studies in asymptomatic children). The etiology is multifactorial and may stem from alterations of the hemostatic system following various chemotherapy protocols (including use of l-Asparaginase), the presence of central venous lines (CVL), as well as comorbidities, e.g. inherited thrombophilia risk factors. Most symptomatic thrombotic events occur in the upper venous system or in the central nervous system (CNS). Prospective studies on the establishment of guidelines for treatment or prevention are lacking. The following review will address the epidemiology, etiology and risk factors for thrombosis, describe the currently available evidence, and address issues associated with diagnosis and treatment.

De Novo Precursor B-Lymphoblastic Leukemia/Lymphoma With Double-Hit Gene Rearrangements (MYC/BCL-2) Presented With Spinal Cord Compression and Acquired Factor XIII Deficiency

Double-hit lymphomas (DHLs) are aggressive mature B-cell neoplasms associated with rearrangements involving MYC and B-cell lymphoma-2 (BCL-2). Such DH events are extremely rare in B-cell precursor acute lymphoblastic leukemia (B-ALL), especially in young adults. A 29-year-old male patient initially presented to emergency department with right mandibular mass of 2 months duration associated with intermittent fever. Laboratory workup revealed very high lactate dehydrogenase at 2,026.0 U/L. Peripheral blood revealed pancytopenia with many circulating blasts (about 77%). Bone marrow (BM) aspirate revealed infiltration with many small sized blasts of very high nucleocytoplasmic ratio, finely dispersed nuclear chromatin and prominent nucleoli. The BM biopsy reflected marked hypercellularity with diffuse replacement by sheets of blasts, positive for TdT, PAX-5, CD10, cMYC, BCL-2 and CD20 with Ki-67 > 90%. Flow cytometry on BM revealed a precursor B-immunophenotype (CD45 (dim), CD19, CD10, Tdt and CD20). The blasts are negative for cytoplasmic and surface IgM. Cytogenetics revealed complex karyotype: 46,XY,del(6)(q21q23),t(8;22)(q24.1;q11.2),t(14;18)(q32;q21)(20). A diagnosis of B-lymphoblastic leukemia/lymphoma with t(8;22)(q24.1;q11.2) and t(14;18)(q32;q21) was made. Fluorescent in situ hybridization (FISH) analysis revealed an abnormal hybridization signal pattern for CDKN2A probe, indicating biallelic (homozygous) deletion of the short arm of chromosome 9 (9p) in 94% of the cells analyzed. The patient had severe life-threatening bleeding despite of normal prothrombin time (PT) and activated partial thromboplastin time (APTT) due to acquired factor XIII deficiency, an overlooked rare coagulopathy disorder. In addition, the patient developed acute sudden onset paraplegia, and magnetic resonance imaging (MRI) of spine showed acute cord compression which necessitated emergency radiotherapy after which chemotherapy was started on hyper-CVAD (hyperfractionated cyclophosphamide, vincristine, adriamycin, and dexamethasone) protocol. MRI showed dramatic resolution of the mass. Very few cases of B-ALL with DH rearrangement with true precursor B-cell phenotype (positivity for TdT with negativity for surface light chain) have been reported. Many of these had frequent central nervous system (CNS) involvement, with complex karyotypes, highly aggressive course, with short survival of less than 1 year. This case however showed very good response to treatment. In contrary to DHL, de novo B-ALL with double-hit rearrangements is more prevalent in pediatrics and young adults. Although most of reported cases represent transformation of follicular lymphoma, our patient’s young age, acute onset and absent lymphadenopathies all support de novo ALL.

High-dose corticosteroid associated with catheter-related thrombosis after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients are at an increased risk of thrombotic complications, most of which are catheter-related and present a substantial challenge. The incidence of CRT varies considerably depending on clinical factors. However, the underlying pathogenesis and risk factors remain unclear.

METHODS

We performed a retrospective nested case-control study in patients following allo-HSCT. Thrombotic episodes were diagnosed based on the clinical suspicion of the physician (pain, swelling, etc.) with subsequent CVC or PICC thrombosis confirmed via duplex ultrasound. Cases with CRT and controls were matched for time of HSCT, age at HSCT, donor source and type of insertion (CVCs or PICC).

RESULTS

During the 8-year period, catheters were placed in 2896 patients, with a total of 40 patients (1.38%) developed CRT, among which 11 were associated with CVCs and 29 were associated with PICCs. The median duration from catheter insertion to thrombosis was 97days. Despite reports of an association between thrombosis and infection, central line-associated bloodstream infection was comparable between groups. No significant differences were noted in terms of primary disease, donor type, conditioning regimen or catheter type between the cases and controls. A multivariate regression analysis identified high-dose corticosteroids as independent risk factors for the development of CRT. CRT seems to negatively affect prognosis in allo-HSCT patients.

CONCLUSION

In conclusion, we demonstrate that the use of high-dose corticosteroids is correlated with the onset of CRT. However, the efficacy and safety of thromboprophylaxis in this population require further investigation.

Screening for coagulopathy and identification of children with acute lymphoblastic leukemia at a higher risk of symptomatic venous thrombosis: an AIEOP experience

INTRODUCTION

Venous thromboembolic events (VTEs) are frequent complications of childhood acute lymphoblastic leukemia (ALL) treatment. The aim of the study was to evaluate the rate of symptomatic VTEs in children with ALL and the predictive value of clinical and biological factors and routine monitoring of coagulation parameters in identifying children at a higher risk of this complication.

MATERIALS AND METHODS

Between September 2000 and July 2006, 2042 children (≥1 and younger than 18 y) with newly diagnosed ALL were enrolled in Italy in the AIEOP (Italian Association of Pediatric Hematology and Oncology)-BFM (Berlin-Frankfurt-Muenster) ALL 2000 trial. Patients with symptomatic VTEs (deep venous thromboses or cerebral venous thromboses) were identified after a careful review of clinical records. The impact of coagulation derangement at the onset of VTEs was evaluated by a nested case-control study.

RESULTS

Forty-eight (2.4%) children presented with a VTE. The rate of VTEs was higher in male patients (P=0.001); patients randomized to receive dexamethasone tended to have a higher rate of VTE compared with those who received prednisone (P=0.10). The coagulation derangement at the onset of VTE was not associated with VTE occurrence. The prevalence of a factor V Leiden G1691A mutation and the prothrombin G20210A variant was higher in children with VTE than that expected in the general population.

The evaluation of protein Z levels of children with acute lymphoblastic leukaemia during induction therapy

The objective of this study was to evaluate the protein Z levels of children with acute lymphoblastic leukaemia (ALL) during induction therapy. Although several studies investigated the association between steroid and L-asparaginase (L-ASP) administration and levels of coagulation proteins such as protein C, protein S and antithrombin in children with ALL, protein Z levels have not been examined in any study yet. Peripheral blood was drawn from the study group before chemotherapy (PZ0) at diagnosis, at 12th day (PZ1), 15th day (PZ2), 18th day (PZ3) and 21st day (PZ4) of treatment wherein L-ASP treatment is given along with steroid administration according to ALL BFM-1995 chemotherapy protocol. Plasma protein Z levels were measured by enzyme immunoassay method. Mean protein Z level at PZ0 was 1.628 ± 0.485 μg/ml in the study group and 1.672 ± 0.662 μg/ml in the control group. No statistical difference was observed. In the study group, there was a slight increase in protein Z levels between the PZ0 and PZ1 periods in which only steroid therapy was administered. Statistically significant decrease was observed between protein Z levels in PZ0-PZ4, PZ1-PZ2, PZ1-PZ3, PZ1-PZ4 and PZ3-PZ4 periods. During the induction treatment, symptomatic haemorrhage or thrombosis was not followed up in any patients. We demonstrated that children with ALL have similar protein Z values to those of the control group at diagnosis. A significant decrease occurs at the end of the induction treatment with steroid and L-ASP administration. However, this deficiency does not result in development of symptomatic thrombosis or bleeding in these patients.

Thrombosis and acute leukemia

Thrombosis is a common complication in patients with acute leukemia. While the presence of central venous lines, concomitant steroids, the use of Escherichia coli asparaginase and hereditary thrombophilic abnormalities are known risk factors for thrombosis in children, information on the pathogenesis, risk factors, and clinical outcome of thrombosis in adult patients with acute lymphoid leukemia (ALL) or acute myeloid leukemia (AML) is still scarce. Expert consensus and guidelines regarding leukemia-specific risk factors, thrombosis prevention, and treatment strategies, as well as optimal type of central venous catheter in acute leukemia patients are required. It is likely that each subtype of acute leukemia represents a different setting for the development of thrombosis and the risk of bleeding. This is perhaps due to a combination of different disease-specific pathogenic mechanisms of thrombosis, including the type of chemotherapy protocol chosen, the underlying patients health, associated risk factors, as well as the biology of the disease itself. The risk of thrombosis may also vary according to ethnicity and prevalence of hereditary risk factors for thrombosis; thus, it is advisable for Latin American, Asian, and African countries to report on their specific patient population.

The frequency and management of asparaginase-related thrombosis in paediatric and adult patients with acute lymphoblastic leukaemia treated on Dana-Farber Cancer Institute consortium protocols

The optimal management of asparaginase-associated thrombotic complications is not well-defined. We report the features, management and outcome of paediatric (ages 0-18years) and adult (18-50years) patients with acute lymphoblastic leukaemia (ALL) with asparaginase-related venous thromboembolic events (VTE) treated at Dana-Farber Cancer Institute on clinical trials for newly diagnosed ALL between 1991-2008. Of 548 patients, 43 (8%) had VTE, including 27/501 (5%) paediatric and 16/47 (34%) adult patients. Sinus venous thrombosis occurred in 1·6% of patients. Age was the only significant predictor of VTE, with those aged >30years at very high risk (VTE rate 42%). 74% of patients received low molecular weight heparin after VTE. Complications of anticoagulation included epistaxis (9%), bruising (2%) and, in two adult patients, major bleeding. Thirty patients (70%) ultimately received at least 85% of the intended doses of asparaginase. 33% of patients experienced recurrent VTE (paediatric 17% vs. adults 47%, P=0·07). The 48-month event-free survival for patients with VTE was 85±6% compared with 88±2% for those without VTE (P=0·36). This study confirms that, after VTE, asparaginase can be restarted with closely monitored anticoagulation after imaging demonstrates clot stabilization or improvement. With this management strategy, a history of VTE does not appear to adversely impact prognosis.

Cerebral thrombotic complications in adolescent leukemia/lymphoma patients treated with L-asparaginase-containing chemotherapy

We described the cerebral thrombotic complications developed in 2 adolescent patients treated with L-asparaginase-containing regimens. For determining risk factors, we retrospectively analysed hemostatic markers in 19 pediatric patients with leukemia or lymphoma who were treated with either 1 of the 2 L-asparaginase-containing regimens; 11 were treated with VLP1 and the remaining 8 were treated with the VLAD protocol. The data indicated that low coagulation factors in association with increased plasma D-dimer levels during or post-L-asparaginase administration combined with fresh frozen plasma infusion might have activated coagulation processes in these patients. Careful management is required to prevent such episodes in patients with markedly decreased coagulation factors and increased D-dimer levels following L-asparaginase administration.

Thrombosis in childhood acute lymphoblastic leukaemia: epidemiology, aetiology, diagnosis, prevention and treatment

Acute lymphoblastic leukaemia (ALL) is the most common malignancy associated with venous thromboembolism (VTE) in children. The prevalence of symptomatic VTE ranges from 0% to 36%, and the variation can be explained, at least in part, by differences in chemotherapeutic protocols. The mechanism for increased risk of VTE is associated with alterations in the haemostatic system by use of L-asparaginase (ASP) alone or in combination with vincristine or prednisone, presence of central venous lines (CVLs) and/or inherited thrombophilia. The children at greatest risk are generally those receiving Escherichia coli ASP concomitant with prednisone. The majority of symptomatic VTEs occur in the central nervous system or in the upper venous system. In the majority of cases, asymptomatic VTEs are associated with CVLs. External CVLs are affected more often than internal CVLs. Evidence-based guidelines on prevention and treatment guidelines for ALL-related VTE are lacking, and carefully designed clinical trials are needed urgently.

Prevalence of post-thrombotic syndrome following asymptomatic thrombosis in survivors of acute lymphoblastic leukemia

BACKGROUND

Deep vein thrombosis (DVT) is a complication of treatment of acute lymphoblastic leukemia (ALL) in children but little is known about the long-term outcomes of these DVT.

OBJECTIVE

To determine the incidence of post-thrombotic syndrome (PTS) in (i) children with ALL diagnosed with asymptomatic DVT using radiographic testing and (ii) an unselected group of ALL survivors.

METHODS

Cross-sectional study in two populations. Group I comprised children in the Prophylactic Antithrombin Replacement in Kids with ALL treated with L-Asparaginase (PARKAA) study diagnosed with DVT by radiographic tests. Group II consisted of non-selected childhood ALL survivors <21 years. PTS was assessed using a standardized scoring sheet.

RESULTS

Group I: 13 PARKAA patients (median age 12 years) were assessed, and 7 had PTS (54%; 95% CI, 25-81). All patients had collaterals, three also had increased arm circumference. Group II: 41 patients (median age 13 years) with a history of ALL were enrolled, and 10 had PTS (24%; 95% CI, 11-38). All patients had collaterals; five also had increased arm circumference.

CONCLUSION

There is a high incidence of PTS in survivors of childhood ALL with radiographically diagnosed asymptomatic DVT. A significant proportion of ALL survivors develop PTS, indicating previously undiagnosed DVT.

Thrombosis and acute lymphoblastic leukaemia

Venous thrombosis is more frequent in patients treated for acute lymphoblastic leukaemia (ALL) than other malignancies and has distinctive causes, clinical features and remedies. The reported incidence varies from 1% to 36%, depending on the chemotherapy protocol and whether the reported cases are symptomatic or detected on screening radiography. The risk is thought to arise from increased thrombin generation at diagnosis combined with reduced thrombin inhibitory capacity due to depletion of circulating anti-thrombin (AT) by asparaginase. A number of patient and treatment variables have been reported to influence the risk of thrombosis including hereditary thrombophilia, early insertion of central venous catheters and exposure to a combination of steroids and asparaginase during induction. Erwinia asparaginase is associated with a lower risk of thrombosis compared with Escherichia coli asparaginase. The majority of symptomatic thromboses are related to central venous catheters and involve the upper venous system. Central nervous system thrombosis involving the cerebral venous sinuses is a unique feature of asparaginase-related thrombosis and is reported to occur in 1-3% of patients. Conclusive evidence to support the use of anti-coagulant treatment or AT concentrates for primary prevention is lacking, as is evidence for the efficacy of AT concentrates in the management of established thrombosis. Preventative strategies are hampered by conflicting data on factors that would enable identification of those at highest risk of thrombosis.

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.

Thrombotic complications in childhood acute lymphoblastic leukemia: a meta-analysis of 17 prospective studies comprising 1752 pediatric patients

The risk of thrombosis in children with acute lymphoblastic leukemia (ALL) reportedly ranges between 1% and 37%. Epidemiologic studies have usually been hampered by small numbers, making accurate estimates of thrombosis risk in ALL patients very difficult. The aim of this study was to better estimate the frequency of this complication and to define how the disease, its treatment, and the host contribute to its occurrence. We made an attempt to combine and analyze all published data on the association between pediatric ALL and thrombosis, by using a meta-analytic method. The rate of thrombosis in 1752 children from 17 prospective studies was 5.2% (95% CI: 4.2-6.4). The risk varies depending on several factors. Most of the events occurred during the induction phase of therapy. Lower doses of asparaginase (ASP) for long periods were associated with the highest incidence of thrombosis, as were anthracyclines and prednisone (instead of dexamethasone). The presence of central lines and of thrombophilic genetic abnormalities also appeared to be frequently associated with thrombosis. In conclusion, the overall thrombotic risk in ALL children was significant, and the subgroup analysis was able to identify high-risk individuals, a finding that will hopefully guide future prospective studies aimed at decreasing this risk.

Epidemiology of venous thromboembolism in neonates and children

Venous thromboembolism is an increasingly recognised problem in paediatric practice, particularly in the context of tertiary care paediatric services. In recent years, several national and international registries have helped to define the epidemiology of venous thromboembolism in both neonates and older children. These studies have generated information on the incidence and risk factors associated with venous thromboembolism in different age groups. Data from these and other studies have demonstrated important differences between paediatric and adult practice and highlight the need for specific evidence based guidelines for the prevention and management of venous thromboembolism in neonates and children.

Thrombosis in children with acute lymphoblastic leukemia

At diagnosis, there is evidence of increased thrombin generation in children with acute lymphoblastic leukemia (ALL), the etiology of which is unclear. However, thromboembolism (TE) in children with ALL is most commonly reported after the initiation of antileukemic therapy indicating a possible interaction of the disease and therapy. Antileukemic therapy influences the haemostatic system either by direct effect of the chemotherapeutic agents or indirectly through the effect of supportive care, e.g. central venous line (CVL) or infectious complications secondary to immunosuppression. Asparaginase and steroids are shown to induce hypercoagulable state by suppression of natural anticoagulants, especially AT and plasminogen, and by elevations in F VIII/vWF complex, respectively. In addition, steroid therapy causes hypofibrinolytic state by dose-dependent increase in plasminogen activator inhibitor 1 (PAI-1) levels. Combination of these effects coupled with increased thrombin generation may be responsible for the increased incidence of TE observed with concomitant administration of asparaginase and steroids. Further studies to delineate the mechanism of increased thrombin in generation children with ALL and effects of various chemotherapeutic agents, in isolation and in combination, on haemostatic system are needed.

Thrombosis in children with acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common childhood malignancy. With the advent of aggressive multimodality therapy, ALL has become a curable disease for majority of pediatric patients. Thromboembolism (TE) is a well-recognized serious complication in association with ALL leading to significant morbidity. It can be potentially fatal in over 50% of the affected patients. Development of TE does interfere with the scheduled treatment plan for ALL and, thus, ultimate outcome from ALL. Recent evidence indicates that concomitant administration of asparaginase and steroids is likely to be associated with higher incidence of TE, especially in children with at least one prothrombotic risk factor. In addition, older children and patients with high risk ALL may be at higher risk for developing TE. However, the epidemiology and the exact pathogenesis of this entity have not yet been clearly defined. To reduce the incidence of TE and its impact on overall outcome as well as on the quality of life in children undergoing treatment for ALL, further studies to define the epidemiology of TE in relation to the biology of ALL and chemotherapy protocols are urgently needed. The purpose of this review is to evaluate the current knowledge of TE in association with ALL in children, especially in relation with the treatment protocols and genetic background. This review will be published in three parts. The first part will review the available information regarding epidemiology of TE in children with ALL.

Low plasma levels of hemostatic proteins during the induction phase in children with acute lymphoblastic leukemia: A retrospective study by the JACLS. Japan Association of Childhood Leukemia Study

BACKGROUND

Thromboembolic and bleeding events are serious complications associated with the administration of L-asparaginase (ASP) during the induction phase in children with acute lymphoblastic leukemia (ALL). Prophylactic supplementation of plasma-derived coagulation products remains controversial. The purposes of this study were to examine the plasma levels of hemostatic proteins during the induction phase and the efficacy of prophylactic replacement of plasma-derived products.

METHODS

A multicenter retrospective survey on the incidence of hemostatic complications and the frequency of prophylactic replacement of plasma-derived products among children with ALL who under went ASP therapy was conducted. All patients were treated according to the Japan Association of Childhood Leukemia Study (JACLS) ALL-97 protocol.

RESULTS

Thirty-six (67%) of the 54 JACLS-treatment centers responded and provided information on 127 patients. Clinically relevant hemostatic complications occurred in two patients (1.6%;2/127); one patient suffered intracranial bleeding 5 days after beginning the protocol, and the second patient suffered an ischemic attack during an ASP treatment. The administration of ASP(10 000 u/m2 x six doses) led to significant reductions in the plasma fibrinogen (180 +/- 74 to 105 +/- 57 mg/dL),antithrombin III (AT III) (126 +/- 21 to 73 +/- 18%),and plasminogen levels (97 +/- 17 to 52 +/- 18%). These laboratory parameters returned to normal levels 2 weeks after completion of the ASP treatment. Forty-eight patients (38%)received AT III concentrate (AT III-supplement group). The AT III level of the AT III-supplement group was significantly lower than that of the AT III non-supplement group, not only during the ASP therapy, but also prior to the ASP therapy. A greater percentage of patients in the AT III-supplement group received fresh-frozen plasma and in greater amounts than those in the AT III non-supplement group.

CONCLUSIONS

Severe hemorrhage and thrombosis were uncommon in the ALL patients who underwent ASP therapy in comparison with the degree of coagulation changes. Prophylactic administration of AT III concentrate or fresh-frozen plasma did not demonstrate clear beneficial effects in the treatment of ALL in preventing thromboembolic events.