The prophylaxis of venous thrombosis in patients with cancer undergoing major abdominal surgery: emerging options

Cancer-Associated Thrombosis: Pathophysiology, Laboratory Assessment, and Current Guidelines

Dysregulated hemostasis in cancer patients is associated with various clinical conditions, from thromboembolic complications to disseminated intravascular coagulation. Despite the well-established association between cancer and thromboembolic complications, the mechanisms involved are not completely elucidated. There are several predisposing factors in cancer for increased thrombus generation, such as immobilization and chemotherapy. The term cancer-associated thrombosis (CAT) has been introduced to describe the close bidirectional relationship between cancer and thromboembolic events. Conventional coagulation tests (PT/aPTT) are more accurate in detecting a hypocoagulable rather than a hypercoagulable state; thus, their contribution to CAT management is limited. Traditionally, D-dimer levels have been the most common laboratory study for the evaluation of thrombotic risk. However, D-dimer levels only display a snapshot of the coagulation cascade, and they cannot provide a dynamic evaluation of evolving clot formation. Non-conventional assays, such as viscoelastic methods and microparticle formation are promising tools for the identification of patients at risk for developing CAT. Recent guidelines from the American Society of Clinical Oncology counsel against the estimation of thrombotic risk through a single test and recommend the use of scoring systems that take into account several risk factors. The present review outlines the current insights into the pathophysiological mechanisms of CAT and provides a comprehensive review of the latest advances in the laboratory assessment of CAT and the recent guidelines for the management of patients at risk for developing thromboembolic complications.

Characteristics and significance of changes of thrombomodulin and plasma protein C in patients with cancer before and after PICC

Objective

This study aimed to evaluate the changes and clinical significance of thrombomodulin (TM) and plasma protein C (PC) in patients with cancer before and after peripherally inserted central catheter placement (PICC).

Materials and Methods

The levels of plasma TM and PC in 35 patients with cancer before and after PICC were measured by enzyme-linked immunosorbent assay, and the significance of the differences was analyzed.

Results

TM was 3.57 ± 1.01 μg/L at 1 day after catheterization, which was significantly lower than the value of 4.41 ± 1.26 μg/L before catheterization; these values were 4.30 ± 1.81 and 4.73 ± 0.97 μg/L at 30 and 90 days after catheterization, respectively (F = 4.14,P < 0.05). PC was 3.32 ± 1.35 μg/L at 1 day after catheterization, which was significantly lower than the value of 5.32 ± 2.12 μg/L before catheterization; these values were 4.64 ± 2.44 and 5.83 ± 3.14 μg/L at 30 and 90 days after catheterization, respectively (F = 6.28,P < 0.01). There were no significant differences in platelet (PLT) counts, plasma D-D, and coagulation parameters among the four time points before and after catheterization. There was a positive correlation between TM and PC (r = 0.5420,P < 0.01) on day 1 after PICC line insertion. The levels of TM and PC were not related to PLT, plasma D-dimer, or various coagulation parameters.

Conclusions

The levels of TM and PC in the patients 1 day after PICC were significantly decreased and showed a positive correlation, but were not related to PLT, plasma D-dimer, or coagulation function.

Venous thromboembolic events in lymphoma patients: Actual relationships between epidemiology, mechanisms, clinical profile and treatment

Venous thromboembolic events (VTE) are an underestimated health problem in patients with lymphoma. Many factors contribute to the pathogenesis of thromboembolism and the interplay between various mechanisms that provoke VTE is still poorly understood. The identification of parameters that are associated with an increased risk of VTE in lymphoma patients led to the creation of several risk-assessment models. The models that evaluate potential VTE risk in lymphoma patients in particular are quite limited, and have to be validated in larger study populations. Furthermore, the VTE prophylaxis in lymphoma patients is largely underused, despite the incidence of VTE. The lack of adequate guidelines for the prophylaxis and treatment of VTE in lymphoma patients, together with a cautious approach due to an increased risk of bleeding, demands great efforts to ensure the implementation of current knowledge in order to reduce the incidence and complications of VTE in lymphoma patients.

In Surgical Colon Cancer Patients Extended-Duration Thromboprophylaxis (30 days) with the Highest Dose of Tinzaparin (4,500 IU s.c./q.d.) Normalizes the Postoperative VEGF Levels

Background/Purpose: In colon cancer (CC) patients preoperative (pre-op) levels of VEGF-A₁₆₅ (VEGF) is a strong predictor for disease recurrence. Elevated postoperative (post-op) VEGF levels could have undesirable effects by enhancing tumor growth and metastasis formation. It has been suggested that thromboprophylaxis with a Low Molecular Weight Heparin (LMWH) in surgical cancer patients, further to thromboembolic protection, may exert some anti-neoplastic properties, as well. The aim of our study was to assess the potential impact of the LMWH Tinzaparin (Innohep® - Leo Pharma, Copenhagen, Denmark), given at different doses and for different perioperative (peri-op) periods, upon the post-op variability of serum VEGF levels in surgical CC patients. Methods: A total of 54 consecutive CC patients who underwent a curative resection were randomized in four groups according to their peri-op thromboprophylaxis scheme, which was based on administrating Tinzaparin in different doses and at different periods, as follows: group I: 3,500 IU for 10 days, group II: 3,500 IU for 30 days, group III: 4,500 IU for 10 days and group IV: 4,500 IU for 30 days. Serum VEGF concentrations were evaluated on the pre-op day (Day 0) and on the 10^th and 30^th post-op days (Day 10 and Day 30, respectively). For statistical analyses the mixed design ANOVA was used. P < 0.05 was considered significant. Results: On Day 0, VEGF didn't differ between groups I, II, III and IV (p>0.05, for every comparison). On Day 10, VEGF was increased in all groups. Between Day 10 and Day 30, VEGF remained stable in groups I (p=0.031) and II (p=1.000) and increased significantly in group III (p=0.005). On the contrary, VEGF decreased significantly in group IV (p<0.001). The most remarkable finding was observed when we compared VEGF between Day 0 and Day 30: while in groups I, II and III, VEGF remained significantly higher compared to Day 0 (p<0.001, p=0.041 and p<0.001, respectively), on the contrary, in group IV (extended-duration with the highest dose of 4,500 IU of tinzaparin) it was comparable to Day 0 (p=1.000). Conclusions: In surgical CC patients only the recommended thromboprophylaxis scheme with the highest prophylactic dose of Tinzaparin (4,500 IU) for extended-duration (30 days) normalizes VEGF levels at the end of the first post-op month by reducing them to the pre-op levels.

Thromboprophylaxis in ambulatory lung cancer treatment

Venous thromboembolism (VTE), including deep vein thrombosis and pulmonary embolism, are common problems experienced by patients with lung cancer that can impact treatment plans, prognoses, and survival. Patients with lung cancer are at greatest risk for development of VTE in the ambulatory care treatment setting. Literature does exist on VTE management for medical and surgical oncology inpatients, as well as clinical guidelines for inpatient prophylaxis; however, published evidence is lacking on outpatient risk and thromboprophylaxis in medical oncology outpatients, particularly patients with lung cancer. Because patients with lung cancer treated in the ambulatory setting have established risks for VTE, they may benefit from thromboprophylaxis. Clinical guidelines for outpatient thromboprophylaxis direct the clinical practice for thromboprophylaxis in lung cancer treatment. The purpose of the current article is to explore the VTE risks associated with ambulatory lung cancer treatment and to review the recommended guidelines for thromboprophylaxis to guide clinical decision making for patients with lung cancer.

Cancer-associated thrombosis

Cancer-associated thrombosis accounts for almost one-fifth of all cases of venous thromboembolism (VTE) and is a leading cause of death, morbidity, delays in care, and increased costs. Our understanding of risk factors for cancer-associated thrombosis has expanded in recent years, and investigators have begun to use biomarkers and clinical prediction models to identify those cancer patients at greatest risk for VTE. The Khorana Risk Model, which is based on easily obtained biomarkers and clinical factors, has now been validated in several studies. Recent clinical trials of prophylaxis and treatment of VTE in cancer patients are reviewed here. In addition, consensus guidelines and expert opinion regarding management of VTE in specific challenging situations are presented.

Association study of selected genetic polymorphisms and occurrence of venous thromboembolism in patients with multiple myeloma who were treated with thalidomide

INTRODUCTION/BACKGROUND

Venous thromboembolism (VTE), with the subsequent risk of pulmonary embolism, is a common adverse effect of thalidomide treatment in patients with multiple myeloma (MM). In our retrospective study, we analyzed candidate single-nucleotide polymorphisms (SNP), CINP (rs7011), CETP (rs289747), ALDH1A1 (rs610529), CDKN1A (rs3829963), GAN (rs2608555), vascular endothelial growth factor (rs699947), and ALDH1A1 (rs168351), previously identified in a large association study based on the hypothesis-driven candidate gene approach nominated by the International Myeloma Foundation "Bank On A Cure" (3404 SNPs). In that study, the researchers built a classification tree that enables prediction of individual risk of VTE in patients with MM.

PATIENTS AND METHODS

Genotypes of these SNPs were determined in an independent cohort of 111 patients with MM through TaqMan real-time polymerase chain reaction (PCR) allelic discrimination and were used for prediction of individual VTE risk.

RESULTS

The results of this study did not confirm the ability of this classification tree to predict VTE risk in patients with MM from the Czech Republic; of these patients, 21 (19%) developed high-grade VTE. However, in patients with VTE, we found higher frequency of the AC genotype in the CDKN1A gene (42.9% vs. 16.7%; odds ratio 3.64) in comparison with the CC genotype (P = .015). SNPs of other genes as well as age and sex of the patients had no statistically significant influence on the risk of VTE.

CONCLUSION

Further studies are needed to confirm the initial analysis that provided predictive information of genetic variations in patients with myeloma that may influence risk of VTE.

Emerging risk stratification approaches to cancer-associated thrombosis: risk factors, biomarkers and a risk score

Cancer patients are well-known to be at increased risk of venous thromboembolism (VTE). However, the risk varies widely between patients and over the natural history of malignancy. Recent data have identified multiple clinical risk factors as well as biomarkers predictive of VTE. Risk factors include patient-associated factors such as age, obesity and medical comorbidities, cancer-associated factors such as site and stage of cancer, and treatment-associated factors, particularly chemotherapy and anti-angiogenic therapy. Biomarkers associated with increased risk of cancer-associated VTE include leukocyte count, platelet count, and levels of tissue factor, P-selectin and D-dimer. This review focuses on the evidence for risk stratification of cancer patients, based on these risk factors and biomarkers, as well as a recently validated predictive model which can be used to identify patients at highest risk. Targeted thromboprophylaxis utilizing model-based and/or biomarker-based approaches may provide an optimal risk-benefit ratio and is currently the focus of ongoing clinical trials.

[Venous thromboembolic disease in general surgery]

About one-fourth of patients undergoing general surgery and not receiving antithrombotic prophylaxis will suffer postoperative venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) of the legs and pulmonary embolism (PE). Apart from fatal PE, which affects 0.8% of general surgical patients, about one-third of patients with DVT will develop long-term complications, such as posthrombotic syndrome and recurrent VTE. The best strategy to reduce the high morbidity and mortality associated with postoperative VTE, is to use some of the available prophylactic methods which have been shown to be effective and safe for VTE prevention. The most widely investigated and implemented methods in western countries are the pharmacological agents, namely heparin and their low molecular weight fractions, as well as mechanical methods, such as elastic stockings and intermittent pneumatic compression of the legs. Appropriate prophylaxis measures should be implemented according to the characteristics of each patient and the surgical operation to be done.