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

Primary Thromboprophylaxis in Patients with Malignancies: Daily Practice Recommendations by the Hemostasis Working Party of the German Society of Hematology and Medical Oncology (DGHO), the Society of Thrombosis and Hemostasis Research (GTH), and the Austrian Society of Hematology and Oncology (ÖGHO)

Patients with cancer, both hematologic and solid malignancies, are at increased risk for thrombosis and thromboembolism. In addition to general risk factors such as immobility and major surgery, shared by non-cancer patients, cancer patients are exposed to specific thrombotic risk factors. These include, among other factors, cancer-induced hypercoagulation, and chemotherapy-mediated endothelial dysfunction as well as tumor-cell-derived microparticles. After an episode of thrombosis in a cancer patient, secondary thromboprophylaxis to prevent recurrent thromboembolism has long been established and is typically continued as long as the cancer is active or actively treated. On the other hand, primary prophylaxis, even though firmly established in hospitalized cancer patients, has only recently been studied in ambulatory patients. This recent change is mostly due to the emergence of direct oral anticoagulants (DOACs). DOACs have a shorter half-life than vitamin K antagonists (VKA), and they overcome the need for parenteral application, the latter of which is associated with low-molecular-weight heparins (LMWH) and can be difficult for the patient to endure in the long term. Here, first, we discuss the clinical trials of primary thromboprophylaxis in the population of cancer patients in general, including the use of VKA, LMWH, and DOACs, and the potential drug interactions with pre-existing medications that need to be taken into account. Second, we focus on special situations in cancer patients where primary prophylactic anticoagulation should be considered, including myeloma, major surgery, indwelling catheters, or immobilization, concomitant diseases such as renal insufficiency, liver disease, or thrombophilia, as well as situations with a high bleeding risk, particularly thrombocytopenia, and specific drugs that may require primary thromboprophylaxis. We provide a novel algorithm intended to aid specialists but also family practitioners and nurses who care for cancer patients in the decision process of primary thromboprophylaxis in the individual patient.

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.

Venous thromboembolism in patients with esophageal or gastric cancer undergoing neoadjuvant chemotherapy

There is a well-established link between cancer and venous thromboembolism (VTE), and patients receiving chemotherapy for esophageal or gastric cancer appear at high risk of developing VTE. The incidence of VTE in the neoadjuvant setting in these patients is poorly understood, as is the role for thromboprophylaxis during neoadjuvant chemotherapy. A PubMed search was conducted using a combination of terms including; esophageal & gastric cancer, deep venous thrombosis (DVT), VTE, neoadjuvant, chemotherapy and chemoradiotherapy. One hundred and fifty-four articles were retrieved and a narrative review was conducted. For patients with esophageal and gastric cancer the incidence of VTE ranged from 4 to 19%. Gastric cancer (Odds Ratio [OR] 6.38, [95% CI: 1.96-20.80]) and Stage III/IV disease, (OR 5.16 [95% CI: 1.29-20.73]) were identified as risk factors for developing VTE. Neoadjuvant chemotherapy was identified as an independent risk factor for developing VTE. Symptomatic and asymptomatic VTE have a similar effect on mortality. Median overall survival for asymptomatic VTE was 13.9 months (95% CI: 5.0-∞) versus 12.8 months (95% CI: 4.7-30.3) if the VTE was symptomatic. Neoadjuvant chemotherapy is a significant risk factor for VTE in patients with esophageal and gastric cancer. Intervention to minimize the risk using pharmacological and mechanical thromboprophylaxis should be considered, and this should start in the neoadjuvant period.

Primary prophylaxis for venous thromboembolism in patients undergoing cardiac or thoracic surgery

BACKGROUND

Cardiac and thoracic surgery are associated with an increased risk of venous thromboembolism (VTE). The safety and efficacy of primary thromboprophylaxis in patients undergoing these types of surgery is uncertain.

OBJECTIVES

To assess the effects of primary thromboprophylaxis on the incidence of symptomatic VTE and major bleeding in patients undergoing cardiac or thoracic surgery.

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched May 2014) and CENTRAL (2014, Issue 4). The authors searched the reference lists of relevant studies, conference proceedings, and clinical trial registries.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs comparing any oral or parenteral anticoagulant or mechanical intervention to no intervention or placebo, or comparing two different anticoagulants.

DATA COLLECTION AND ANALYSIS

We extracted data on methodological quality, participant characteristics, interventions, and outcomes including symptomatic VTE and major bleeding as the primary effectiveness and safety outcomes, respectively.

MAIN RESULTS

We identified 12 RCTs and one quasi-RCT (6923 participants), six for cardiac surgery (3359 participants) and seven for thoracic surgery (3564 participants). No study evaluated fondaparinux, the new oral direct thrombin, direct factor Xa inhibitors, or caval filters. All studies had major study design flaws and most lacked a placebo or no treatment control group. We typically graded the quality of the overall body of evidence for the various outcomes and comparisons as low, due to imprecise estimates of effect and risk of bias. We could not pool data because of the different comparisons and the lack of data. In cardiac surgery, 71 symptomatic VTEs occurred in 3040 participants from four studies. In a study of 2551 participants, representing 85% of the review population in cardiac surgery, the combination of unfractionated heparin with pneumatic compression stockings was associated with a 61% reduction of symptomatic VTE compared to unfractionated heparin alone (1.5% versus 4.0%; risk ratio (RR) 0.39; 95% confidence interval (CI) 0.23 to 0.64). Major bleeding was only reported in one study, which found a higher incidence with vitamin K antagonists compared to platelet inhibitors (11.3% versus 1.6%, RR 7.06; 95% CI 1.64 to 30.40). In thoracic surgery, 15 symptomatic VTEs occurred in 2890 participants from six studies. In the largest study evaluating unfractionated heparin versus an inactive control the rates of symptomatic VTE were 0.7% versus 0%, respectively, giving a RR of 6.71 (95% CI 0.40 to 112.65). There was insufficient evidence to determine if there was a difference in the risk of major bleeding from two studies evaluating fixed-dose versus weight-adjusted low molecular weight heparin (2.7% versus 8.1%, RR 0.33; 95% CI 0.07 to 1.60) and unfractionated heparin versus low molecular weight heparin (6% and 4%, RR 1.50; 95% CI 0.26 to 8.60).

AUTHORS' CONCLUSIONS

The evidence regarding the efficacy and safety of thromboprophylaxis in cardiac and thoracic surgery is limited. Data for important outcomes such as pulmonary embolism or major bleeding were often lacking. Given the uncertainties around the benefit-to-risk balance, no conclusions can be drawn and a case-by-case risk evaluation of VTE and bleeding remains preferable.

Comparison of LMWH versus UFH for hemorrhage and hospital mortality in the treatment of acute massive pulmonary thromboembolism after thrombolytic treatment : randomized controlled parallel group study

PURPOSE

Current guidelines recommend the use of low molecular weight heparin (LMWH) for most haemodynamically stable patients with pulmonary thromboembolism (PTE), however, it is not clear whether LMWH is preferable to unfractionated heparin (UFH) for the treatment of massive PTE. We aimed to compare the use of LMWH versus UFH after thrombolytic treatment in the management of acute massive PTE for hemorrhage and hospital mortality.

METHODS

The study, a randomized, single center, parallel design trial, included the patients who had confirmed the diagnosis of massive PTE according to clinical findings and computerized thorax angiography and no contraindication to the treatment between January 2011 and October 2013. After thrombolytic treatment, the patients assigned to therapy with LMWH or UFH. Any hemorrhage, major hemorrhage, and hospital mortality were assessed.

RESULTS

A total of 121 patients, 71 female (58.7 %) and 50 male (41.3 %), who had massive PTE with an average age 62.6 ± 15.7 (ranges 22-87) were included for analyses in the study. They were allocated to either LMWH (n = 60) or UFH (n = 61) group. Although the occurrence of any adverse event (21.7 vs 27.9 %) and each individual type of adverse event were all lower in the LMWH group compared to UFH group (6.7 vs 11.5 %, 3.3 vs 9.8 %, and 15.0 vs 19.7 % for death, major hemorrhage, and any hemorrhage, respectively), the differences were not statistically significant.

CONCLUSIONS

Our findings suggest that LMWH might be a better option in the management of the patients with massive PTE. Multi-center larger randomized controlled trials are required to confirm our results.

Venous thromboembolic prophylaxis after a hepatic resection: patterns of care among liver surgeons

INTRODUCTION

No consensus exists for post-hepatectomy venous thromboembolic (VTE) prophylaxis. Factors impacting VTE prophylaxis patterns among hepato-pancreato-biliary (HPB) surgeons were defined.

METHOD

Surgeons were invited to complete a web-based survey on VTE prophylaxis. The impact of physician and clinical factors was analysed.

RESULTS

Two hundred responses were received. Most respondents were male (91%) and practiced at academic centres (88%) in the United States (80%). Surgical training varied: HPB (24%), transplantation (24%), surgical oncology (34%), HPB/transplantation (13%), or no specialty (5%). Respondents estimated VTE risk was higher after major (6%) versus minor (3%) resections. Although 98% use VTE prophylaxis, there was considerable variability: sequential compression devices (SCD) (91%), unfractionated heparin Q12h (31%) and Q8h (32%), and low-molecular weight heparin (39%). While 88% noted VTE prophylaxis was not impacted by operative indication, 16% stated major resections reduced their VTE prophylaxis. Factors associated with the decreased use of pharmacologic prophylaxis included: elevated international normalized ratio (INR) (74%), thrombocytopaenia (63%), liver insufficiency (58%), large EBL (46%) and complications (8%). Forty-seven per cent of respondents wait until ≥post-operative day 1 (POD1) and 35% hold pharmacologic VTE prophylaxis until no signs of coagulopathy. A minority (14%) discharge patients on pharmacologic prophylaxis. While 81% have institutional VTE guidelines, 79% believe hepatectomy-specific guidelines would be helpful.

CONCLUSION

There is considerable variation regarding VTE prophylaxis among liver surgeons. While most HPB surgeons employ VTE prophylaxis, the methods, timing and purported contraindications differ significantly.

Effect of heparin on prevention of flap loss in microsurgical free flap transfer: a meta-analysis

The effectiveness of heparin for thromboprophylaxis during microvascular free flap transfer is uncertain. The purpose of this meta-analysis was to determine the effect of heparin on the prevention of flap loss in microsurgical free flap transfer.A search of PubMed, Cochrane databases, and Google Scholar using combinations of the search terms heparin, free flap, flap loss, free tissue transfer was conducted on March 15, 2013. Inclusion criteria were: 1) Prospective randomized trials. 2) Retrospective, non-randomized studies. 3) Patients received free tissue transfer. Flap loss rate was used to evaluate treatment efficacy. Odds ratios (ORs) with 95% confidence intervals (CI) were calculated and compared between therapies. Four studies meet the criteria for analysis and were included. Two studiescompared aspirin and heparin, and the ORs of the 2 studies were 1.688 and 2.087. The combined OR of 2.003 (95% CI 0.976–4.109, p = 0.058) did not indicate any significant difference between heparin and aspirin therapies. Two studiescompared high and low doses of dalteparin/heparin therapies, and the ORs of the 2 studies were 4.691 and 11.00. The combined OR of 7.810 (95% CI 1.859–32.808, p = 0.005) revealed a significant difference indicating that high dose dalteparin or heparin therapy is associated with a greater flap loss rate than low dose therapy. Heparin and aspirin prophylaxis are associated with similar flap loss rates after free flap transfer, and high dose dalteparin or heparin therapy is associated with a greater flap loss rate than low dose therapy.

[Prophylaxis and treatment of venous thromboembolism in cancer patients. Clinical value of low-molecular-weight heparins]

Venous thromboembolism (VTE) is a common complication in patients with cancer. Because of their improved subcutaneous bioavailability and reliable antithrombotic efficiency low-molecular-weight heparins (LMWH) are preferably used for prevention and treatment of cancer-related VTE. Thromboprophylaxis with LMWH is well established in patients undergoing cancer surgery and hospitalized cancer patients, while outpatient prophylaxis remains contentious. LMWH are recommended over unfractionated heparins and vitamin K antagonists for initial treatment and secondary prophylaxis (3-6 months) after cancer-related VTE. Long-term secondary prophylaxis should be considered for patients with ongoing active malignancy and low bleeding risk. Due to absence of clinical studies in cancer patients, the use of novel oral anticoagulants is currently not recommended.

Fatal paraneoplastic embolisms in both circulations in a patient with poorly differentiated neuroendocrine tumour

Arterial embolism with lower limb ischemia is a rare manifestation of paraneoplastic hypercoagulability in cancer patients. We report a unique case of fatal thromboembolism involving both circulations associated with a poorly differentiated neuroendocrine tumor of the lung with rapid progress despite high doses of unfractioned heparin and review the current literature on anticoagulative regimen in tumour patients.

Venous thromboembolism prevention in patients undergoing colorectal surgery for cancer

INTRODUCTION

Patients undergoing surgery for colorectal cancer are at high risk of post-operative venous thromboembolism (VTE). Thromboprophylaxis has been shown to have significant risk reduction, although there remains some controversy surrounding the optimal duration of pharmacological prophylaxis. Our institution does not routinely practise extended prophylaxis. The aim of this study was to retrospectively review the rate of post-operative thromboprophylaxis in colorectal cancer patients, and incidence of symptomatic VTE.

METHODS

We conducted a retrospective audit of 200 consecutive patients who underwent colorectal surgery for cancer. Data to 90 days post-operatively were collected from medical records and imaging and phone calls to patients and family practitioners.

RESULTS

Of the patients, 98% received pharmacological prophylaxis, with a median duration of eight days. Eight (4%) symptomatic VTEs were diagnosed within the 90-day follow-up period: two deep vein thrombosis (DVTs), five pulmonary emboli (PE) and one patient with both PE and DVT. A higher proportion of patients developed DVT/PE if they received prophylaxis other than low molecular weight heparin and similarly there was a trend in increased risk of DVT in the presence of metastatic disease. However, using univariate analysis, these results were not statistically significant (P = 0.18 and 0.11, respectively).

DISCUSSION

The use of thromboprophylaxis was high in our centre, and the incidence of VTE was low when patients received a median of 8 days pharmacological prophylaxis combined with mechanical prophylaxis. The VTE incidence of 4% is similar to previous studies using extended prophylaxis. Our study findings do not support changing local protocol to extended prophylaxis.

Systematic evaluation of the methodology of randomized controlled trials of anticoagulation in patients with cancer

Background

Randomized controlled trials (RCTs) that are inappropriately designed or executed may provide biased findings and mislead clinical practice. In view of recent interest in the treatment and prevention of thrombotic complications in cancer patients we evaluated the characteristics, risk of bias and their time trends in RCTs of anticoagulation in patients with cancer.

Methods

We conducted a comprehensive search, including a search of four electronic databases (MEDLINE, EMBASE, ISI the Web of Science, and CENTRAL) up to February 2010. We included RCTs in which the intervention and/or comparison consisted of: vitamin K antagonists, unfractionated heparin (UFH), low molecular weight heparin (LMWH), direct thrombin inhibitors or fondaparinux. We performed descriptive analyses and assessed the association between the variables of interest and the year of publication.

Results

We included 67 RCTs with 24,071 participants. In twenty one trials (31%) DVT diagnosis was triggered by clinical suspicion; the remaining trials either screened for DVT or were unclear about their approach. 41 (61%), 22 (33%), and 11 (16%) trials respectively reported on major bleeding, minor bleeding, and thrombocytopenia. The percentages of trials satisfying risk of bias criteria were: adequate sequence generation (85%), adequate allocation concealment (61%), participants’ blinding (39%), data collectors’ blinding (44%), providers’ blinding (41%), outcome assessors’ blinding (75%), data analysts’ blinding (15%), intention to treat analysis (57%), no selective outcome reporting (12%), no stopping early for benefit (97%). The mean follow-up rate was 96%. Adequate allocation concealment and the reporting of intention to treat analysis were the only two quality criteria that improved over time.

Conclusions

Many RCTs of anticoagulation in patients with cancer appear to use insufficiently rigorous outcome assessment methods and to have deficiencies in key methodological features. It is not clear whether this reflects a problem in the design, conduct or the reporting of these trials, or both. Future trials should avoid the shortcomings described in this article.

Heparin inhibits Hepatocyte Growth Factor induced motility and invasion of hepatocellular carcinoma cells through early growth response protein 1

The Hepatocyte Growth Factor (HGF)/c-Met signaling pathway regulates hepatocyte proliferation, and pathway aberrations are implicated in the invasive and metastatic behaviors of hepatocellular carcinoma (HCC). In addition to c-Met, heparin acts as a co-receptor to modulate pathway activity. Recently, anti-metastatic and anti-cancer effects of heparin have been reported. However, the role of heparin in the regulation of HGF signaling remains controversial and the effects of heparin on HGF-induced biological responses during hepatocarcinogenesis is not yet defined. In this study we determined the effects of heparin on HGF-induced activities of HCC cells and the underlying molecular mechanisms. Here, we report for the first time that heparin inhibits HGF-induced adhesion, motility and invasion of HCC cells. In addition, heparin reduced HGF-induced activation of c-Met and MAPK in a dose-dependent manner, as well as decreased transcriptional activation and expression of Early growth response factor 1 (Egr1). HGF-induced MMP-2 and MMP-9 activation, and MT1-MMP expression, also were inhibited by heparin. Stable knockdown of Egr1 caused a significant decrease in HGF-induced invasion, as well as the activation and expression of MMPs. Parallel to these findings, the overexpression of Egr1 increased the invasiveness of HCC cells. Our results suggest that Egr1 activates HGF-induced cell invasion through the regulation of MMPs in HCC cells and heparin inhibits HGF-induced cellular invasion via the downregulation of Egr1. Therefore, heparin treatment might be a therapeutic approach to inhibit invasion and metastasis of HCC, especially for patients with active HGF/c-Met signaling.