Low molecular weight heparin versus unfractionated heparin for perioperative thromboprophylaxis in patients with cancer

Thromboprophylaxis in oesophageal cancer patients-a study protocol for a randomised, controlled trial (TOP-RCT)

BACKGROUND

The purpose of the study is to examine if prolonged thromboprophylaxis decreases the risk of thrombosis after intended curative surgery for oesophageal cancer. Study results are expected to inform a guideline for thromboprophylaxis after oesophageal cancer surgery. The perspective is to reduce morbidity and mortality in this critically ill patient group. Thrombosis is the second-most common cause of cancer death after the cancer itself. The risk of thrombosis depends on the cancer type, and upper gastrointestinal cancers are considered high risk. This risk is further increased when patients undergo surgery. However, only few studies have investigated the peri- and postoperative coagulation profile in oesophageal cancer patients. Due to this lack of knowledge, prophylaxis is currently restricted to 5000 IU (international units) low-molecular weight heparin daily from surgery until discharge from hospital (approximately 10 days), whereas patients with gastric cancer receive 30 days of treatment. The present study examines whether a 30-day treatment is superior and safe, compared with the current standard treatment.

METHODS

The study is a randomised controlled trial. Inclusion is ongoing, and we aim to include 100 patients. Blood samples are drawn before and after surgery, and the coagulation is extensively examined. The primary endpoint is the difference in plasma levels of prothrombin fragment 1 + 2 (F1 + 2) 30 days after surgery between the intervention and the standard group. Furthermore, patients are examined with ultrasound to screen for asymptomatic venous thrombotic events (VTE). Secondary endpoints are incidence of bleeding, symptomatic and asymptomatic VTE and mortality 30 days 1 one year after surgery.

DISCUSSION

The study will provide valuable information on the perioperative coagulation profile and VTE risk of oesophageal cancer patients. The study seeks to aid in optimising the postoperative thromboprophylaxis, and the perspective is to reduce morbidity and mortality in this at-risk patient population.

TRIALS REGISTRATION

The trial was prospectively registered at the EU Clinical Trials Register with ID 2021-001335-24 on 30 June 2021 and at ClinicalTrials.gov with study identifier NCT05067153.

Venous thromboembolic events following cytoreductive surgery for lower gastrointestinal neoplasia

Introduction

Cytoreductive surgery (CRS) and intraperitoneal chemotherapy (IPC) represent a high-risk for venous thromboembolism (VTE) due to malignancy, prolonged surgery and immobility. We investigated the incidence of and risk factors for VTE following CRS/IPC.

Materials and methods

Data was analysed on 130 CRS/IPC performed over a 6-year period at a single centre, the Western Australian Peritonectomy Service (WAPS), on lower gastrointestinal neoplasia: pseudomyxoma peritoneii (PMP), colorectal cancer (CRC) and appendix cancer (AC). Data was analysed by univariate and multivariate logistic regression to identify risk factors for VTE.

Results

31 patients (24 %) experienced a VTE. The percentages of VTE among patients with PMP (n = 50), CRC (n = 53) and AC (n = 27) were 36 %, 17 % and 15 % respectively. 60 % of these cases were asymptomatic. The odds of VTE were higher for PMP patients than in patients with a other histopathology (OR=2.9, p = 0.01). Other significant risk factors for VTE on univariate analysis were PCI (OR=1.07, p = 0.001), pelvic dissection (OR=5.52, p = 0.001) and operation time (OR=1.36, p = 0.001).

Conclusion

This study demonstrates high rates of VTE in patients undergoing CRS/IPC. Patients with PMP have a three-fold higher risk of VTE compared to other malignancies (CRC+AC). As most VTE cases were asymptomatic, aggressive early investigation and intervention is indicated for patients undergoing CRS/IPC.

Cancer-associated thrombosis and drug-drug interactions of antithrombotic and antineoplastic agents

Venous thromboembolism (VTE) is often associated with malignant diseases and notably contributes to morbidity and mortality in patients with cancer. Cancer-associated thrombosis (CAT) brings additional costs to health expenditures and has a negative impact on oncological outcomes. Either the recurrence rate of VTE or bleeding complications are also higher in patients with cancer. Prophylactic anticoagulation has been recommended in peri-surgical periods, inpatient settings, and high-risk ambulatory patients. Although various risk stratification scores are used, none are ideal for identifying patients who can benefit from anticoagulant prophylaxis. New risk scoring systems or biomarkers are needed to identify patients who are more likely to benefit from prophylaxis with low bleeding risk. The questions about the patients who will be given prophylaxis and those who develop thromboembolism, with which drug, and how long they will be treated are still not fully answered. Anticoagulation is the cornerstone of the treatment, but management of CAT remains complex. Low molecular weight heparins and direct oral anticoagulants are effective and safe options for the treatment of CAT. Recognizing adverse effects, drug-drug interactions, and accompanying conditions that cause dose adjustment is crucial. Prevention and treatment of VTE in patients with cancer require a multidisciplinary and patient-based approach. PLAIN LANGUAGE SUMMARY: Cancer-associated thrombosis is a significant cause of mortality and morbidity in patients with cancer. Chemotherapy, surgery, and/or use of central venous access remarkably increase the risk of thrombosis. Prophylactic anticoagulation should be considered not only in inpatient follow-up and during peri-surgical period but also ambulatory patients with a high risk of thrombosis. Many parameters, such as drug-drug interactions, primary side of cancer, and comorbidities of patients should be considered when selecting anticoagulant drugs. More accurate risk stratification scores or biomarkers are still an unmet need.

New prophylaxis strategies to reduce the risk of thromboembolism in cancer

INTRODUCTION

: Patients with cancer are at risk of thrombotic events, mainly deep vein thrombosis and/or pulmonary embolism. The thrombosis risk is generally 4-6 times higher than in a healthy population and depends on factors related to patient characteristics, tumor factors, and treatment-related factors. The decision-making for prophylactic anticoagulation is individualized according to the relative risks and benefits. The VTE risk has been quantified using different assessment scores. In recent years, an effort has been made to establish "risk assessment models" specifically for patients undergoing chemotherapy.

AREAS COVERED

This article reviews current data and ongoing research on predictive factors involved in cancer-related thrombosis and it is highlighted the currently suggested strategies for prophylaxis. Several trials that compared the two treatment options, direct factor Xa inhibitor or LMWH, with placebo and not each other are discussed. In this article, was analyzed the safety and efficacy features that led several international organizations such as ASCO, NCCN, and others, to issue guidelines for the prophylaxis and treatment of patients at high risk of thrombosis by using LMWH, fondaparinux and DOACs.

EXPERT OPINION

ASCO, NCCN, and other international organizations recommend thromboprophylaxis in high risk patients. However, further investigation is needed to define better biomarkers for more accurate identification of cancer patients that will benefit from anticoagulant treatment.

American Society of Hematology 2021 guidelines for management of venous thromboembolism: prevention and treatment in patients with cancer

BACKGROUND

Venous thromboembolism (VTE) is a common complication among patients with cancer. Patients with cancer and VTE are at a markedly increased risk for morbidity and mortality.

OBJECTIVE

These evidence-based guidelines of the American Society of Hematology (ASH) are intended to support patients, clinicians, and other health care professionals in their decisions about the prevention and treatment of VTE in patients with cancer.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The guideline development process was supported by updated or new systematic evidence reviews. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to assess evidence and make recommendations.

RESULTS

Recommendations address mechanical and pharmacological prophylaxis in hospitalized medical patients with cancer, those undergoing a surgical procedure, and ambulatory patients receiving cancer chemotherapy. The recommendations also address the use of anticoagulation for the initial, short-term, and long-term treatment of VTE in patients with cancer.

CONCLUSIONS

Strong recommendations include not using thromboprophylaxis in ambulatory patients receiving cancer chemotherapy at low risk of VTE and to use low-molecular-weight heparin (LMWH) for initial treatment of VTE in patients with cancer. Conditional recommendations include using thromboprophylaxis in hospitalized medical patients with cancer, LMWH or fondaparinux for surgical patients with cancer, LMWH or direct oral anticoagulants (DOAC) in ambulatory patients with cancer receiving systemic therapy at high risk of VTE and LMWH or DOAC for initial treatment of VTE, DOAC for the short-term treatment of VTE, and LMWH or DOAC for the long-term treatment of VTE in patients with cancer.

Quality of Life in Patients With Cancer Under Prolonged Anticoagulation for High-Risk Deep Vein Thrombosis: a Long-Term Follow-Up

Current guidelines recommend to prolong anticoagulant treatment in patients with cancer with venous thromboembolism (VTE); only few studies evaluated other parameters than cancer itself for selecting patients at higher risk of recurrent VTE. Long-term management of VTE is thus challenged by several controversies mainly for patients compliance. We here report results of a long-term follow-up in patients with deep vein thrombosis under anticoagulant treatment with low-molecular-weight heparin (LMWH) for residual vein thrombosis (RVT) detected at compression ultrasonography (CUS), 6 months after standard anticoagulant treatment. Patients with RVT were deemed at high risk of recurrences and included in the current observational study. They continued LMWH (reduced at 75% standard dose) for further additional 2 years after enrolment or until death. Patients were followed up every 3 months or earlier, if needed. Among ancillary study end points, there was the assessment of patients’ quality of life during daily treatment with subcutaneous injections. Quality of life was determined by the EORTC-C30 questionnaire, administered by a skilled psychologist at enrolment and every 6 months follow-up visits. Overall, 128 patients were evaluated during follow-up. Mean global EORTC-C30 score at enrollment and at 6, 12 and 24 months follow-up were 52.1, 51.4, 50.8 and 50.1, respectively. There were no statistically significant differences between scores at enrolment and at the last available follow-up (P = .1). Long-term treatment with LMWH resulted, effective and safe, it was globally well tolerated and exempt of negative impact on quality of life of the enrolled patients. Reported results support long-term anticoagulant treatment with LMWH in cancer patients at risk of recurrent VTE.

American Society of Hematology 2019 guidelines for management of venous thromboembolism: prevention of venous thromboembolism in surgical hospitalized patients

BACKGROUND

Venous thromboembolism (VTE) is a common source of perioperative morbidity and mortality.

OBJECTIVE

These evidence-based guidelines from the American Society of Hematology (ASH) intend to support decision making about preventing VTE in patients undergoing surgery.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline-development process, including performing systematic reviews. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 30 recommendations, including for major surgery in general (n = 8), orthopedic surgery (n = 7), major general surgery (n = 3), major neurosurgical procedures (n = 2), urological surgery (n = 4), cardiac surgery and major vascular surgery (n = 2), major trauma (n = 2), and major gynecological surgery (n = 2).

CONCLUSIONS

For patients undergoing major surgery in general, the panel made conditional recommendations for mechanical prophylaxis over no prophylaxis, for pneumatic compression prophylaxis over graduated compression stockings, and against inferior vena cava filters. In patients undergoing total hip or total knee arthroplasty, conditional recommendations included using either aspirin or anticoagulants, as well as for a direct oral anticoagulant over low-molecular-weight heparin (LMWH). For major general surgery, the panel suggested pharmacological prophylaxis over no prophylaxis, using LMWH or unfractionated heparin. For major neurosurgery, transurethral resection of the prostate, or radical prostatectomy, the panel suggested against pharmacological prophylaxis. For major trauma surgery or major gynecological surgery, the panel suggested pharmacological prophylaxis over no prophylaxis.

Enhanced recovery after surgery (ERAS) programs for esophagectomy

A perioperative treatment protocol, enhanced recovery after surgery (ERAS) focuses on accelerating patient recovery. Previous studies confirmed that ERAS decreases surgical trauma and the stress response, which improved outcomes including reduced length of hospital stay (LOS) and decreased postoperative morbidity. While ERAS protocols have been successfully implemented in a variety of surgical disciplines (colorectal, bariatric, orthopedic, and gynecologic surgery), its use in esophageal surgery is still limited. This paper analyzes the feasibility and value of the ERAS protocol for esophageal surgery. Reviewing the literature found that implementation of ERAS resulted in decreased costs, length of stay and pulmonary specific complication reduction, but not overall morbidity. The evidence lacks randomized control trials. Further, the ERAS Society published recommendations for esophageal resection. This opportunity for unification of the protocol would make the studies more comparable and leads to stronger conclusions. Surgery specific items also require further confirmation. Nonetheless, the successful introduction of the ERAS protocol into a wide variety of surgical disciplines provides optimism for ERAS's effectiveness in esophageal surgery.

[Clinical Value Evaluation of Perioperative Prophylactic Anticoagulation Therapy for Lung Cancer Patients]

BACKGROUND

The incidence of pulmonary embolism (PE) in lung cancer patients who underwent surgery increased during the perioperative period, and prophylactic anticoagulation therapy was important part of enhanced recovery after surgery (ERAS). However, the timing of preventive anticoagulation in patients with lung cancer remained controversial. This study was designed to investigate the safety and efficacy of perioperative prophylactic anticoagulation therapy for lung cancer patients.

METHODS

Retrospective research was conducted on 562 lung cancer patients who underwent video-assisted thoracoscopic (VATS) anatomic pulmonary resections in West China Hospital from June 2016 to December 2016. 56 patients were treated with low molecular weight heparin (LMWH) anticoagulation 12 hours before operation until discharge, while the other 506 patients were treated with LMWH 24 hours after operation until discharge. The postoperative chest drainage volume, postoperative bleeding, pulmonary embolism incidence, and respiratory complications were analyzed.

RESULTS

(1) There were no significant differences in prothrombin time (PT), activated partial thromboplastin time (APTT) and international normalized ratio (INR) between the pre-operation prophylactic anticoagulation group (PRE group) [(11.5±3.9) s, (27.8±3.5) s, (0.96±0.06) s] and the post-operation prophylactic anticoagulation group (POST group) [(11.4±1.4) s, (28.3±4.0) s, (0.98±0.07) s] (P=0.796, P=0.250, P=0.137), and there was no significant difference in Caprini score between the PRE group (3.1±1.8) and the POST group (3.3±1.5) (P=0.104). (2) There were no significant differences in anesthesia time and intraoperative bleeding between PRE group [(130.2±53.9) min, (76.8±49.3) mL] and POST group [(142.2±56.5) min, (73.7±41.6) mL] (P=0.067, P=0.201). (3) The total drainage volume in 72 hours after operation in PRE group [(728.1±505.7) mL] was significantly higher than that of POST group [(596.4±373.5) mL] (P=0.005), while there were no significant differences between the two groups in total postoperative drainage volume [(1,066.8±1,314.6) mL vs (907.8±999.8) mL, P=0.203]. (4) There were no significant differences between the two groups in pulmonary embolism incidence (1.785% vs 0.019%, P=0.525) and postoperative bleeding rates (1.785% vs 0.039%, P=0.300). (5) There were no significant differences between PRE group and POST group in subcutaneous emphysema incidence (1.785% vs 1.581%, P=0.989) and pulmonary infection rates (14.285% vs 6.324%, P=0.085).

CONCLUSIONS

The clinical value of preoperative prophylactic anticoagulation is equal to postoperative prophylactic anticoagulation for lung cancer patients.

Anticoagulation for perioperative thromboprophylaxis in people with cancer

BACKGROUND

The choice of the appropriate perioperative thromboprophylaxis for people with cancer depends on the relative benefits and harms of different anticoagulants.

OBJECTIVES

To systematically review the evidence for the relative efficacy and safety of anticoagulants for perioperative thromboprophylaxis in people with cancer.

SEARCH METHODS

This update of the systematic review was based on the findings of a comprehensive literature search conducted on 14 June 2018 that included a major electronic search of Cochrane Central Register of Controlled Trials (CENTRAL, 2018, Issue 6), MEDLINE (Ovid), and Embase (Ovid); handsearching of conference proceedings; checking of references of included studies; searching for ongoing studies; and using the 'related citation' feature in PubMed.

SELECTION CRITERIA

Randomized controlled trials (RCTs) that enrolled people with cancer undergoing a surgical intervention and assessed the effects of low-molecular weight heparin (LMWH) to unfractionated heparin (UFH) or to fondaparinux on mortality, deep venous thrombosis (DVT), pulmonary embolism (PE), bleeding outcomes, and thrombocytopenia.

DATA COLLECTION AND ANALYSIS

Using a standardized form, we extracted data in duplicate on study design, participants, interventions outcomes of interest, and risk of bias. Outcomes of interest included all-cause mortality, PE, symptomatic venous thromboembolism (VTE), asymptomatic DVT, major bleeding, minor bleeding, postphlebitic syndrome, health related quality of life, and thrombocytopenia. We assessed the certainty of evidence for each outcome using the GRADE approach (GRADE Handbook).

MAIN RESULTS

Of 7670 identified unique citations, we included 20 RCTs with 9771 randomized people with cancer receiving preoperative prophylactic anticoagulation. We identified seven reports for seven new RCTs for this update.The meta-analyses did not conclusively rule out either a beneficial or harmful effect of LMWH compared with UFH for the following outcomes: mortality (risk ratio (RR) 0.82, 95% confidence interval (CI) 0.63 to 1.07; risk difference (RD) 9 fewer per 1000, 95% CI 19 fewer to 4 more; moderate-certainty evidence), PE (RR 0.49, 95% CI 0.17 to 1.47; RD 3 fewer per 1000, 95% CI 5 fewer to 3 more; moderate-certainty evidence), symptomatic DVT (RR 0.67, 95% CI 0.27 to 1.69; RD 3 fewer per 1000, 95% CI 7 fewer to 7 more; moderate-certainty evidence), asymptomatic DVT (RR 0.86, 95% CI 0.71 to 1.05; RD 11 fewer per 1000, 95% CI 23 fewer to 4 more; low-certainty evidence), major bleeding (RR 1.01, 95% CI 0.69 to 1.48; RD 0 fewer per 1000, 95% CI 10 fewer to 15 more; moderate-certainty evidence), minor bleeding (RR 1.01, 95% CI 0.76 to 1.33; RD 1 more per 1000, 95% CI 34 fewer to 47 more; moderate-certainty evidence), reoperation for bleeding (RR 0.93, 95% CI 0.57 to 1.50; RD 4 fewer per 1000, 95% CI 22 fewer to 26 more; moderate-certainty evidence), intraoperative transfusion (mean difference (MD) -35.36 mL, 95% CI -253.19 to 182.47; low-certainty evidence), postoperative transfusion (MD 190.03 mL, 95% CI -23.65 to 403.72; low-certainty evidence), and thrombocytopenia (RR 3.07, 95% CI 0.32 to 29.33; RD 6 more per 1000, 95% CI 2 fewer to 82 more; moderate-certainty evidence). LMWH was associated with lower incidence of wound hematoma (RR 0.70, 95% CI 0.54 to 0.92; RD 26 fewer per 1000, 95% CI 39 fewer to 7 fewer; moderate-certainty evidence). The meta-analyses found the following additional results: outcomes intraoperative blood loss (MD -6.75 mL, 95% CI -85.49 to 71.99; moderate-certainty evidence); and postoperative drain volume (MD 30.18 mL, 95% CI -36.26 to 96.62; moderate-certainty evidence).In addition, the meta-analyses did not conclusively rule out either a beneficial or harmful effect of LMWH compared with Fondaparinux for the following outcomes: any VTE (DVT or PE, or both; RR 2.51, 95% CI 0.89 to 7.03; RD 57 more per 1000, 95% CI 4 fewer to 228 more; low-certainty evidence), major bleeding (RR 0.74, 95% CI 0.45 to 1.23; RD 8 fewer per 1000, 95% CI 16 fewer to 7 more; low-certainty evidence), minor bleeding (RR 0.83, 95% CI 0.34 to 2.05; RD 8fewer per 1000, 95% CI 33 fewer to 52 more; low-certainty evidence), thrombocytopenia (RR 0.35, 95% CI 0.04 to 3.30; RD 14 fewer per 1000, 95% CI 20 fewer to 48 more; low-certainty evidence), any PE (RR 3.13, 95% CI 0.13 to 74.64; RD 2 more per 1000, 95% CI 1 fewer to 78 more; low-certainty evidence) and postoperative drain volume (MD -20.00 mL, 95% CI -114.34 to 74.34; low-certainty evidence) AUTHORS' CONCLUSIONS: We found no difference between perioperative thromboprophylaxis with LMWH versus UFH and LMWH compared with fondaparinux in their effects on mortality, thromboembolic outcomes, major bleeding, or minor bleeding in people with cancer. There was a lower incidence of wound hematoma with LMWH compared to UFH.

Thromboprophylaxis in Head and Neck Microvascular Reconstruction

Head and neck patients undergoing microvascular reconstruction are at high risk for thromboembolism. While the prevention of thromboembolism has become an essential aspect of care, within the field of microsurgery, concern for anastomotic complications have hindered the creation of an accepted regimen. The aim of this review was to evaluate the risks and benefits of prophylactic agents for thromboprophylaxis. A literature search was conducted in MEDLINE, Cochrane Library, and PubMed/NCBI databases. Articles discussing thromboprophylaxis in otolaryngology, head and neck surgery, or microvascular reconstruction were considered in the review from the past 30 years. The majority of patients undergoing microvascular surgery have multiple risk factors for thrombus formation. Several consensus guidelines exist for the prophylaxis in patients who are critically ill, undergoing surgery, or with malignancy. Significant evidence supports the routine use of mechanical means, such as early mobilization and pneumatic compression along with subcutaneous heparin. Low-molecular-weight heparin is also frequently utilized, although results are largely divided. Data on aspirin remain equivocal. Studies on microvascular failure and flap loss have demonstrated little to no association with chemoprophylaxis. The evidence for postoperative thromboprophylaxis regimens in patients undergoing head and neck free tissue transfer is variable. Multiple studies have supported the use of unfractionated heparin or low-molecular-weight heparin. There appears to be an expert consensus for the combined use of mechanical prophylactic methods and chemical prophylaxis. Prospective randomized trials are required to validate the most effective combination of chemoprophylaxis agents.

Thrombosis in cancer patients: etiology, incidence, and management

Venous thromboembolism (VTE) is the second most common cause of mortality in cancer patients. The mechanisms of cancer-associated thrombosis (CAT), much like cancer itself, are multi-factorial and incompletely understood. Cancer type, stage, tumor-derived factors and genetics all affect CAT risk. Furthermore, cancer therapies as well as the indwelling vascular devices through which these therapies are delivered can increase the risk for CAT. In this review, we summarize mechanisms of hypercoagulability in cancer patients, patterns of thrombosis associated with cancer, current guidelines for the diagnosis and management of CAT, and important considerations regarding the placement of implantable vascular devices in the care of cancer patients with VTE.

International clinical practice guidelines including guidance for direct oral anticoagulants in the treatment and prophylaxis of venous thromboembolism in patients with cancer

Venous thromboembolism (VTE) is the second leading cause of death in patients with cancer. These patients are at an increased risk of developing VTE and are more likely to have a recurrence of VTE and bleeding while taking anticoagulants. Management of VTE in patients with cancer is a major therapeutic challenge and remains suboptimal worldwide. In 2013, the International Initiative on Thrombosis and Cancer (ITAC-CME), established to reduce the global burden of VTE in patients with cancer, published international guidelines for the treatment and prophylaxis of VTE and central venous catheter-associated thrombosis. The rapid global adoption of direct oral anticoagulants for management of VTE in patients with cancer is an emerging treatment trend that needs to be addressed based on the current level of evidence. In this Review, we provide an update of the ITAC-CME consensus recommendations based on a systematic review of the literature ranked according to the Grading of Recommendations Assessment, Development, and Evaluation scale. These guidelines aim to address in-hospital and outpatient cancer-associated VTE in specific subgroups of patients with cancer.

Unfractionated heparin versus low molecular weight heparins for avoiding heparin-induced thrombocytopenia in postoperative patients

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is an adverse drug reaction presenting as a prothrombotic disorder related to antibody-mediated platelet activation. It is a paradoxical immune reaction resulting in thrombin generation in vivo, which leads to a hypercoagulable state and the potential to initiate venous or arterial thrombosis. A number of factors are thought to influence the incidence of HIT including the type and preparation of heparin (unfractionated heparin (UFH) or low molecular weight heparin (LMWH)) and the heparin-exposed patient population, with the postoperative patient population at higher risk.Although LMWH has largely replaced UFH as a front-line therapy, there is evidence supporting a lack of superiority of LMWH compared with UFH regarding prevention of deep vein thrombosis and pulmonary embolism following surgery, and similar frequencies of bleeding have been described with LMWH and UFH. The decision as to which of these two preparations of heparin to use may thus be influenced by harmful effects such as HIT. We therefore sought to determine the relative impact of UFH and LMWH on HIT in postoperative patients receiving thromboembolism prophylaxis. This is an update of a review first published in 2012.

OBJECTIVES

The objective of this review was to compare the incidence of heparin-induced thrombocytopenia (HIT) and HIT complicated by venous thromboembolism in postoperative patients exposed to unfractionated heparin (UFH) versus low molecular weight heparin (LMWH).

SEARCH METHODS

For this update, the Cochrane Vascular Information Specialist searched the Specialised Register (May 2016), CENTRAL (2016, Issue 4) and trials registries. The authors searched Lilacs (June 2016) and additional trials were sought from reference lists of relevant publications.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in which participants were postoperative patients allocated to receive prophylaxis with UFH or LMWH, in a blinded or unblinded fashion. Studies were excluded if they did not use the accepted definition of HIT. This was defined as a relative reduction in the platelet count of 50% or greater from the postoperative peak (even if the platelet count at its lowest remained greater than 150 x 109/L) occurring within five to 14 days after the surgery, with or without a thrombotic event occurring in this timeframe. Additionally, we required circulating antibodies associated with the syndrome to have been investigated through laboratory assays.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias. Disagreements were resolved by consensus with participation of a third author.

MAIN RESULTS

In this update, we included three trials involving 1398 postoperative participants. Participants were submitted to general surgical procedures, minor and major, and the minimum mean age was 49 years. Pooled analysis showed a significant reduction in the risk of HIT with LMWH compared with UFH (risk ratio (RR) 0.23, 95% confidence interval (CI) 0.07 to 0.73); low-quality evidence. The number needed to treat for an additional beneficial outcome (NNTB) was 59. The risk of HIT was consistently reduced comparing participants undergoing major surgical procedures exposed to LMWH or UFH (RR 0.22, 95% CI 0.06 to 0.75); low-quality evidence. The occurrence of HIT complicated by venous thromboembolism was significantly lower in participants receiving LMWH compared with UFH (RR 0.22, 95% CI 0.06 to 0.84); low-quality evidence. The NNTB was 75. Arterial thrombosis occurred in only one participant who received UFH. There were no amputations or deaths documented. Although limited evidence is available, it appears that HIT induced by both types of heparins is common in people undergoing major surgical procedures (incidence greater than 1% and less than 10%).

AUTHORS' CONCLUSIONS

This updated review demonstrated low-quality evidence of a lower incidence of HIT, and HIT complicated by venous thromboembolism, in postoperative patients undergoing thromboprophylaxis with LMWH compared with UFH. Similarily, the risk of HIT in people undergoing major surgical procedures was lower when treated with LMWH compared to UFH (low-quality evidence). The quality of the evidence was downgraded due to concerns about the risk of bias in the included studies and imprecision of the study results. These findings may support current clinical use of LMWH over UFH as front-line heparin therapy. However, our conclusions are limited and there was an unexpected paucity of RCTs including HIT as an outcome. To address the scarcity of clinically-relevant information on HIT, HIT must be included as a core harmful outcome in future RCTs of heparin.

Hypercoagulation and complement: Connected players in tumor development and metastases

Hypercoagulation is a common feature of several tumors to the extent that individuals with coagulation defects often present with occult visceral cancers. Recent evidence has shown that hypercoagulation is not just a mere secondary effect due to the presence of the tumor, rather it actively contributes to tumor development and dissemination. Among the numerous mechanisms that can contribute to cancer-associated hypercoagulation, the ones involving immune-mediated processes are gaining increasing attention. In particular, complement cascade and hypercoagulation are one inducing the other in a vicious circle that involves neutrophil extracellular traps (NETs) formation. Together, in this feedback loop, they can promote the protumorigenic phenotype of immune cells and the protection of tumor cells from immune attack, ultimately favouring tumor development, progression and metastases formation. In this review, we summarize the role of these processes in cancer development and highlight new possible intervention strategies based on anticoagulants that can arrest this vicious circle.