Deep vein thrombosis (DVT) and pulmonary embolism (PE): awareness and prophylaxis practices reported by patients with cancer.

Patients with cancer are at increased risk for venous thromboembolism (VTE). An online survey to measure PE/DVT terminology awareness and understanding of VTE risks revealed 24% and 15% of the 500 cancer patients surveyed had heard of term DVT/PE; 19% and 17% could name signs/ symptoms of DVT/PE; 3% recognized cancer treatments as risk factors for DVT/PE. Only 25% of the patients received prevention education from providers; <50% received VTE prophylaxis. Cancer patient awareness of VTE terminology and cancer and/or its treatment as risk for VTE is low. More effective patient/physician dialogue about VTE risk and thromboprophylaxis is needed.

Pattern of frequent but nontargeted pharmacologic thromboprophylaxis for hospitalized patients with cancer at academic medical centers: a prospective, cross-sectional, multicenter study.

PURPOSE: Hospitalized patients with cancer are considered to be at high risk for venous thromboembolism (VTE). Despite strong recommendations in numerous clinical practice guidelines, retrospective studies have shown that pharmacologic thromboprophylaxis is underutilized in hospitalized patients with cancer. PATIENTS AND METHODS: We conducted a prospective, cross-sectional study of hospitalized patients with cancer at five academic hospitals to determine prescription rates of thromboprophylaxis and factors influencing its use during hospitalization. RESULTS: A total of 775 patients with cancer were enrolled across five academic medical centers. Two hundred forty-seven patients (31.9%) had relative contraindications to pharmacologic prophylaxis. Accounting for contraindications to anticoagulation, the overall rate of pharmacologic thromboprophylaxis was 74.2% (95% CI, 70.4% to 78.0%; 392 of 528 patients). Among the patients with cancer without contraindications for anticoagulation, individuals hospitalized with nonhematologic malignancies were significantly more likely to receive pharmacologic thromboprophylaxis than those with hematologic malignancies (odds ratio [OR], 2.34; 95% CI, 1.43 to 3.82; P=.007). Patients with cancer admitted for cancer therapy were significantly less likely to receive pharmacologic thromboprophylaxis than those admitted for other reasons (OR, 0.37; 95% CI, 0.22 to 0.61; P<.001). Sixty-three percent of patients with cancer classified as low risk, as determined by the Padua Scoring System, received anticoagulant thromboprophylaxis. Among the 136 patients who did not receive anticoagulation, 58.8% were considered to be high risk by the Padua Scoring System. CONCLUSION: We conclude that pharmacologic thromboprophylaxis is frequently administered to hospitalized patients with cancer but that nearly one third of patients are considered to have relative contraindications for prophylactic anticoagulation. Pharmacologic thromboprophylaxis in hospitalized patients with cancer is commonly prescribed without regard to the presence or absence of concomitant risk factors for VTE.

Safety and feasibility of a diagnostic algorithm combining clinical probability, d-dimer testing, and ultrasonography for suspected upper extremity deep venous thrombosis: a prospective management study.

BACKGROUND: Although well-established for suspected lower limb deep venous thrombosis, an algorithm combining a clinical decision score, d-dimer testing, and ultrasonography has not been evaluated for suspected upper extremity deep venous thrombosis (UEDVT). OBJECTIVE: To assess the safety and feasibility of a new diagnostic algorithm in patients with clinically suspected UEDVT. DESIGN: Diagnostic management study. (ClinicalTrials.gov: NCT01324037) SETTING: 16 hospitals in Europe and the United States. PATIENTS: 406 inpatients and outpatients with suspected UEDVT. MEASUREMENTS: The algorithm consisted of the sequential application of a clinical decision score, d-dimer testing, and ultrasonography. Patients were first categorized as likely or unlikely to have UEDVT; in those with an unlikely score and normal d-dimer levels, UEDVT was excluded. All other patients had (repeated) compression ultrasonography. The primary outcome was the 3-month incidence of symptomatic UEDVT and pulmonary embolism in patients with a normal diagnostic work-up. RESULTS: The algorithm was feasible and completed in 390 of the 406 patients (96%). In 87 patients (21%), an unlikely score combined with normal d-dimer levels excluded UEDVT. Superficial venous thrombosis and UEDVT were diagnosed in 54 (13%) and 103 (25%) patients, respectively. All 249 patients with a normal diagnostic work-up, including those with protocol violations (n = 16), were followed for 3 months. One patient developed UEDVT during follow-up, for an overall failure rate of 0.4% (95% CI, 0.0% to 2.2%). LIMITATIONS: This study was not powered to show the safety of the substrategies. d-Dimer testing was done locally. CONCLUSION: The combination of a clinical decision score, d-dimer testing, and ultrasonography can safely and effectively exclude UEDVT. If confirmed by other studies, this algorithm has potential as a standard approach to suspected UEDVT. PRIMARY FUNDING SOURCE: None.

Capture of lipopolysaccharide (endotoxin) by the blood clot: a comparative study.

In vertebrates and arthropods, blood clotting involves the establishment of a plug of aggregated thrombocytes (the cellular clot) and an extracellular fibrillar clot formed by the polymerization of the structural protein of the clot, which is fibrin in mammals, plasma lipoprotein in crustaceans, and coagulin in the horseshoe crab, Limulus polyphemus. Both elements of the clot function to staunch bleeding. Additionally, the extracellular clot functions as an agent of the innate immune system by providing a passive anti-microbial barrier and microbial entrapment device, which functions directly at the site of wounds to the integument. Here we show that, in addition to these passive functions in immunity, the plasma lipoprotein clot of lobster, the coagulin clot of Limulus, and both the platelet thrombus and the fibrin clot of mammals (human, mouse) operate to capture lipopolysaccharide (LPS, endotoxin). The lipid A core of LPS is the principal agent of gram-negative septicemia, which is responsible for more than 100,000 human deaths annually in the United States and is similarly toxic to arthropods. Quantification using the Limulus Amebocyte Lysate (LAL) test shows that clots capture significant quantities of LPS and fluorescent-labeled LPS can be seen by microscopy to decorate the clot fibrils. Thrombi generated in the living mouse accumulate LPS in vivo. It is suggested that capture of LPS released from gram-negative bacteria entrapped by the blood clot operates to protect against the disease that might be caused by its systemic dispersal.

Evidence for enhanced tissue factor expression in age-related macular degeneration.

Tissue factor (TF) is the primary initiator of blood coagulation. In addition to hemostasis, TF can initiate intracellular signaling and promote inflammation and angiogenesis, the key processes underlying the pathogenesis of age-related macular degeneration (AMD). AMD, the leading cause of irreversible blindness among the elderly, involves many genetic and environmental risk factors, including oxidative stress and inflammation. In this study, TF expression was examined in human AMD tissue and in the eyes of a model of AMD, the Ccl2(-/-)/Cx3cr1(-/-) (DKO) mouse, as well as in the ARPE-19 cell line after lipopolysaccharide (LPS) and H(2)O(2) stimulation. Total RNA was extracted from tissue samples and further analyzed by real-time RT-PCR. Immunohistochemistry was performed to evaluate TF protein expression. In the human retina, a 32-fold increase of TF mRNA expression was detected in AMD macular lesions compared with normal maculae. TF protein expression was also enhanced in human AMD maculae. Similarly, TF transcript and protein expression were moderately increased in retinal lesions, neuroretinal tissue, and cultured RPE cells of DKO mice compared with age-matched wild-type mice. TF expression level correlated with age in both wild-type and DKO mice. In order to better understand how AMD might lead to enhanced TF expression, 1, 5, and 10 µg/ml LPS as well as 100 and 200 µM H(2)O(2) were used to stimulate ARPE-19 cells for 24 and 2 h, respectively. LPS treatment consistently increased TF transcript and protein expression. H(2)O(2) alone or in combination with LPS also moderately enhanced TF expression. These results indicate that upregulated TF expression may be associated with AMD, and inflammatory and oxidative stress may contribute to TF expression in AMD eyes.

Asymptomatic factor VII deficiency: gene analysis and structure-function relationships.

Factor VII Padua is a variant form of factor VII deficiency characterized by a prolongation of the prothrombin time (PT), when the assay is performed using rabbit brain thromboplastin. The PT is normal when performed using either human or ox brain thromboplastin reagents, or a recombinant human tissue factor-based thromboplastin. We report a case of an African-American woman with asymptomatic factor VII deficiency, who had a prolonged PT and factor VII activity levels of 5-8% using rabbit brain thromboplastin, but a normal PT and factor VII activity levels when measured using recombinant human brain thromboplastin or tissue factor. The amino acid substitution (R304Q), which gives rise to factor VII Padua, was found in our patient, making this only the fourth African-American case described to date with this mutation. Our report emphasizes the importance of identifying this benign form of factor VII deficiency in order to avoid unnecessary exposure of patients to treatment with either plasma-derived products or recombinant activated factor VII.

Thrombosis associated with angiogenesis inhibitors.

Recent advances in the understanding of the pathogenesis of cancer have led to the introduction of a variety of biological agents with novel mechanisms of action into clinical trials and even into clinical practice. In particular, tumour-associated neoangiogenesis has become a major target for this new class of antineoplastic agents. Five anti-angiogenic agents (thalidomide, lenalidomide, bevacizumab, sunitinib, sorafenib) have already obtained US Food and Drug Administration approval for clinical use, and many others have entered clinical trials. Many new biological agents with anti-angiogenic properties appear to be associated with an increased risk for thrombosis and, paradoxically, bleeding. Although the mechanisms underlying the increased thromboembolic risk remain ill defined, the main hypothesis is that perturbation of tumour-associated endothelial cells can switch the endothelium from a naturally anticoagulant surface to a prothrombotic surface, thus mediating the activation of systemic coagulation in cancer patients, who are already more susceptible to thromboembolism due to their underlying disease. The toxicity profile differs between the anti-angiogenic agents. Thalidomide, lenalidomide, semaxibin (SU5416) and prinomastat have produced more venous thromboembolic complications, whereas bevacizumab, sunitinib, sorafenib and ZD6126 have been associated with a higher risk of arterial thromboembolism and, in particular, myocardial ischaemia. The observation of these vascular toxicities suggests the need to establish, in randomized clinical trials, the usefulness of thrombosis prophylaxis when anti-angiogenic agents are used in cancer patients, especially when associated with chemotherapy. In addition, careful reporting of haemostatic complications during treatment with new anti-angiogenic drugs is warranted.

Cancer and thrombosis in women - molecular mechanisms.

Both women and men with cancer are at increased risk for developing venous thromboembolism (VTE), a propensity that has been known for many years. Until recently it was assumed, however, that the association between cancer and thrombosis is an epiphenomenon - not causally related to the transforming malignant events. The pathophysiology of thrombosis in patients with cancer is complex involving multiple tumor-related and host-related factors. Several recent studies have provided strong evidence that activation of blood coagulation, perhaps most often mediated by tissue factor (TF)-rich microparticles (MPs), is linked directly to oncogene-induced malignant transformation. In addition, the development of VTE, either before or concurrent with the diagnosis of cancer, appears to predict an aggressive behavior of a tumor, and correlates with increased tumor angiogenesis and early onset of distant metastasis. The regulation of expression of TF in tumor cells is controlled at the molecular level by several oncogenes, as appears to be true for cyclooxygenase-2 (COX-2), an important regulator of platelet function and plasminogen activator inhibitor type 1 (PAI-1), an inhibitor of fibrinolysis. In addition, engagement of protease-activated receptors (PARs) by the TF-factor VIIa complex, factor Xa and/or thrombin, have now been shown to be important for tumor growth, angiogenesis and metastasis. Targeting blood clotting reactions in cancer, therefore, may provide a unique approach to cancer treatment.

Hemostatic complications of angiogenesis inhibitors in cancer patients.

Tumor vasculature and tumor-associated neo-angiogenesis have recently become major targets for rational drug design of antineoplastic agents. Five such agents with angiogenesis inhibiting activity (thalidomide, lenalidomide, bevacizumab, sunitinib, sorafenib) have already obtained US Food and Drug Administration approval for clinical use and many others have entered clinical trials. Vascular complications, including venous or arterial thromboembolism and hemorrhage, have emerged as relevant toxicities in several clinical trials with angiogenesis inhibitors. Given the well-known interplay between the blood clotting system, angiogenesis, and tumor growth, a better understanding of the impact of these new drugs on overall hemostatic balance is required. In this brief overview, we discuss the incidence of hemostatic complications, the likely pathogenetic mechanisms involved, and the critical need to establish in randomized clinical trials the usefulness of thrombosis prophylaxis to prevent these complications. Careful documentation of hemostatic complications during treatment with each of the new antiangiogenic drugs is warranted. Further studies are urgently required to better define the causal association of these new agents with hemostatic complications and to establish the best prophylactic strategy.

Hypercoagulability and tissue factor gene upregulation in hematologic malignancies.

Thrombotic complications in patients with hematologic malignancies are as frequent as in those with solid tumors and significantly affect morbidity and mortality. In acute leukemia, thrombosis and bleeding manifestations may occur concomitantly as a part of the same thrombo-hemorrhagic syndrome. In patients with Philadelphia chromosome-negative chronic myeloproliferative disorders (i.e., essential thrombocythemia [ET] and polycythemia vera [PV]), a thrombosis rate as high as 40% has been recorded. A hypercoagulable state is present in virtually all of these patients, even without clinical manifestations. In this review, we focus on the pathogenic mechanisms underlying the hypercoagulable state of these two hematologic malignancies. Although the pathogenesis of hypercoagulability is complex, a central role is played by the fundamental molecular changes of both the leukemic cells and of the progeny arising from the hematopoietic progenitor cells that have undergone clonal rearrangement. These cells overexpress procoagulant factors, as well as adhesion molecules and cytokines capable of inducing procoagulant changes in the vascular wall and stimulating increased cellular interactions. Recent molecular studies in experimental models of human tumors have demonstrated for the first time that oncogene- and repressor gene-mediated neoplastic transformation induces activation of blood coagulation. Similarly, in cells from patients with acute promyelocytic leukemia, the T15-17 translocation induces hyperexpression of tissue factor (TF) and renders the patient hypercoagulable. Furthermore, in blood cells from patients with PV or ET, the presence of the JAK2V617F mutation translates into activation of hemostasis, with increased expression of platelet-associated TF microparticles and the formation of increased platelet/neutrophil aggregates. Understanding the pathophysiology of hypercoagulability is critical to the design of appropriate measures for intervention in these hematologic disorders to prevent thromboembolic complications.