Cancer-associated thrombosis: an update

Effects of malignancy on blood coagulation in septic intensive care patients

: The objectives of the study are to examine the effect of sepsis on the coagulation profile of patients having solid cancer and to test the hypothesis that septic patients with cancer have normal or increased hemostatic capacity despite prolonged standard coagulation tests (SCTs) compared with noninfected cancer patients. Patients with solid cancer were included in the study forming two groups: study group included patients with sepsis with minimum two organ dysfunctions and control group formed by noninfected cancer patients. SCTs, platelet count, plasma levels of coagulation factors and rotation thromboelastometry (TEM International GmbH, Munich, Germany) were determined in both groups. Study group patients (n = 35) showed prolonged SCTs, thrombocytopenia, decreased coagulation factor levels and increased D-dimer compared with control group (n = 35). However, fibrinogen levels and clot firmness assessed by rotation thromboelastometry were not different between groups and clot lysis indexes at 45 and 60 min were increased in study group compared with control group. The first derivative of the clot firmness curve revealed an increased time to the maximum velocity of clot formation for study group, without differences in the maximum velocity of clot formation, or in total thrombus formation. Sepsis with organ dysfunction in cancer patients is associated with delayed initiation of coagulation and reduced fibrinolysis compared with control patients, but overall clot formation and stabilization is not different. For septic cancer patients, SCTs and plasmatic indicators of fibrinolysis do not translate well to whole blood clot formation and may be misleading indicators of thrombotic or bleeding risk.

A retrospective study of venous thromboembolism in acute leukemia patients treated at the University of Texas MD Anderson Cancer Center

The purpose was to determine the incidence and prevalence of venous thromboembolism (VTE) in acute leukemia patients from our institution. We conducted a retrospective study on newly diagnosed acute leukemia patients who presented at our institution from November 1999 to May 2005. Descriptive statistics and cross-tabulation were used to describe patient characteristics. Measures of morbidity were used to address VTE risk. Chi-square testing, Fisher's exact testing, Mann-Whitney analyses, or median testing were used to determine between-group differences. Data analyses were conducted using Stata version 11 (Stata Corp., College Station, TX). Two hundred and ninety-nine patients with acute lymphoblastic leukemia (ALL) and 996 patients with acute myeloid leukemia (AML) were included. After excluding patients diagnosed with VTE prior to or at the time of leukemia diagnosis, during the mean time follow-up period of 2.5 years (range: 0.0025-10.3 years), the overall incidence rate of VTE was 3.7 per 100 person-years: 4.2 per 100 person-years for ALL and 3.4 per 100 person-years for AML. Among all patients, the majority (80.6%) developed VTE within 12 months after diagnosis and during thrombocytopenia. The most common VTE was central venous catheter (CVC)-associated upper-extremity deep venous thrombosis. Pulmonary embolism occurred in 15% of ALL patients and 8% of AML patients. VTE recurred in 20.7% of ALL patients and 18.6% of AML patients. VTE occurs frequently in patients with acute leukemia. Studies are needed to identify risk factors for the development and recurrence of VTE among patients with acute leukemia and to establish more effective methods for preventing and treating VTEs in leukemia patients who have thrombocytopenia and/or CVC.

Ecology meets cancer biology: the cancer swamp promotes the lethal cancer phenotype

As they grow, tumors fundamentally alter their microenvironment, disrupting the homeostasis of the host organ and eventually the patient as a whole. Lethality is the ultimate result of deregulated cell signaling and regulatory mechanisms as well as inappropriate host cell recruitment and activity that lead to the death of the patient. These processes have striking parallels to the framework of ecological biology: multiple interacting ecosystems (organ systems) within a larger biosphere (body), alterations in species stoichiometry (host cell types), resource cycling (cellular metabolism and cell-cell signaling), and ecosystem collapse (organ failure and death). In particular, as cancer cells generate their own niche within the tumor ecosystem, ecological engineering and autoeutrophication displace normal cell function and result in the creation of a hypoxic, acidic, and nutrient-poor environment. This "cancer swamp" has genetic and epigenetic effects at the local ecosystem level to promote metastasis and at the systemic host level to induce cytokine-mediated lethal syndromes, a major cause of death of cancer patients.

Engineered nanoparticles: thrombotic events in cancer

Engineered nanoparticles are being increasingly produced for specific applications in medicine. Broad selections of nano-sized constructs have been developed for applications in diagnosis, imaging, and drug delivery. Nanoparticles as contrast agents enable conjugation with molecular markers which are essential for designing effective diagnostic and therapeutic strategies. Such investigations can also lead to a better understanding of disease mechanisms such as cancer-associated thrombosis which remains unpredictable with serious bleeding complications and high risk of death. Here we review the recent and current applications of engineered nanoparticles in diagnosis and therapeutic strategies, noting their toxicity in relation to specific markers as a target.