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Agnes Y Y Lee

Publications and source records attributed to Agnes Y Y Lee.

18 recordsLinked to original sources
PubMed2006

Incidence, risk factors, and outcomes of catheter-related thrombosis in adult patients with cancer.

PURPOSE: Thrombosis of long-term central venous catheters (CVC) is a serious complication that causes morbidity and interrupts the infusion of chemotherapy, intravenous medication, and blood products. We performed a prospective study to examine the incidence, risk factors, and long-term complications of symptomatic catheter-related thrombosis (CRT) in adults with cancer. PATIENTS AND METHODS: Consecutive patients with cancer, undergoing insertion of a CVC, were enrolled and prospectively followed while their catheter remained in place plus 4 subsequent weeks or a maximum of 52 weeks, whichever came first. Patients with symptomatic CRT were followed for an additional 52 weeks from the date of CRT diagnosis. The end points were symptomatic CRT, symptomatic pulmonary embolism (PE), postphlebitic syndrome, and catheter life span. RESULTS: Over 76,713 patient-days of follow-up, 19 of 444 patients (4.3%) had symptomatic CRT in 19 of 500 catheters (0.3 per 1,000 catheter-days). The median time to CRT was 30 days and the median catheter life span was 88 days. Significant baseline risk factors for CRT were: more than one insertion attempt (odds ratio [OR] = 5.5; 95% CI, 1.2 to 24.6; P = .03); ovarian cancer (OR = 4.8; 95% CI, 1.5 to 15.1; P = .01); and previous CVC insertion (OR = 3.8; 95% CI, 1.4 to 10.4; P = .01). Nine of the 19 CRT patients were treated with anticoagulants alone, eight patients were treated with anticoagulants and catheter removal, while two patients did not receive anticoagulation. None had recurrent CRT or symptomatic PE. Postphlebitic symptoms were infrequent. CONCLUSION: In adults with cancer, the incidence of symptomatic CRT is low and long-term complications are uncommon.

Adolescent↗
PubMed2006

Thrombosis and cancer: the role of screening for occult cancer and recognizing the underlying biological mechanisms.

The association between cancer and thrombosis is well recognized. What is not known, however, is the exact relationship between these two common medical conditions. Although the development of venous thromboembolism (VTE) in a patient with known cancer is the most common presentation, in some patients, VTE may precede the diagnosis of malignancy by many months. The variation in clinical presentation is likely due to the heterogeneous biology of different tumor types and also reflects the limitations of detection or available diagnostic methods. Accumulating evidence now suggests that critical oncogenic events may also trigger activation of the coagulation cascade, leading to a prothrombotic environment that not only manifests as venous thromboembolic disease but also promotes the growth and progression of the malignancy. This chapter will review the evidence for screening for occult malignancy in patients presenting with unprovoked or idiopathic thrombosis, briefly outline the known biological relationships between malignancy and thrombosis, and summarize the clinical data on the potential anticancer effects of low molecular weight heparins (LMWHs).

Heparin, Low-Molecular-Weight↗
PubMed2006

Venous thromboembolism and cancer: prevention and therapy.

Venous thromboembolism (VTE) is a common problem in patients with cancer that complicates management and predicts for a worse prognosis. Hence, effective methods to prevent and treat VTE can reduce morbidity and mortality. Low molecular weight heparins have simplified and improved management of VTE and recent studies suggest these agents may improve survival in cancer patients. This review will provide an update on the primary prevention and treatment of VTE, as well as prophylaxis for central venous catheters, in patients with malignancy.

Anticoagulants↗
PubMed2005

Randomized comparison of low molecular weight heparin and coumarin derivatives on the survival of patients with cancer and venous thromboembolism.

PURPOSE: Experimental studies and indirect clinical evidence suggest that low molecular weight heparins may have antineoplastic effects. We investigated the influence of a low molecular weight heparin dalteparin on the survival of patients with active cancer and acute venous thromboembolism. PATIENTS AND METHODS: Survival data were examined in a posthoc analysis in patients with solid tumors and venous thromboembolism who were randomly assigned to dalteparin or a coumarin derivative for 6 months in a multicenter, open-label, randomized, controlled trial. All-cause mortality at 12 months was compared between treatment groups in patients with and without metastatic malignancy. The effect of dalteparin on survival was compared between the two patient subgroups. RESULTS: During the 12-month follow-up period, 356 of 602 patients with solid tumors and acute venous thromboembolism died. Among patients without metastatic disease, the probability of death at 12 months was 20% in the dalteparin group, as compared with 36% in the oral anticoagulant group (hazard ratio, 0.50; 95% CI, 0.27 to 0.95; P = .03). In patients with metastatic cancer, no difference in mortality between the treatment groups was observed (72% and 69%, respectively; hazard ratio, 1.1; 95% CI, 0.87 to 1.4; P = .46). The observed effects of dalteparin on survival were statistically significantly different between patients with and without metastatic disease (P = .02). CONCLUSION: The use of dalteparin relative to coumarin derivatives was associated with improved survival in patients with solid tumors who did not have metastatic disease at the time of an acute venous thromboembolic event. Additional studies are warranted to investigate these findings.

Acute Disease↗
PubMed2005

Management of thrombosis in cancer: primary prevention and secondary prophylaxis.

Although traditional anticoagulant regimens are highly effective and safe in most patients with venous thromboembolism (VTE), the aggressive natural history of VTE and the high risk of serious bleeding in cancer patients can complicate the management of VTE. In addition, because few clinical trials have focused on the prevention and treatment of VTE in this unique patient population, many clinical questions regarding the care of cancer patients with VTE remain unanswered. Currently, low-molecular-weight heparins and oral vitamin K antagonists are the most commonly used agents for the primary and secondary prophylaxis of VTE in patients with or without cancer, but their use is associated with pharmacological and practical limitations. This review will provide an up-to-date summary of the clinical trials that have addressed the management of VTE in patients with cancer. A brief discussion of the potential application of novel anticoagulants in these clinical settings is also included.

Anticoagulants↗
PubMed2004

Deep venous thrombosis.

Venous thromboembolism (VTE), manifested as either deep venous thrombosis (DVT) or pulmonary embolism (PE), is an extremely common medical problem, occurring either in isolation or as a complication of other diseases or procedures. Yet, despite its frequency, much remains to be learned regarding the pathogenic mechanisms that initiate VTE, about tailoring its treatment to the individual with her/his specific set of risk factors for recurrence, and about its medical management when associated with specific disease entities, such as cancer. These three topics are addressed in this chapter. In Section I, Drs. López and Conde discuss the mechanisms by which venous thrombi may be initiated on the vessel wall in the absence of anatomically overt vessel wall injury. The authors propose a model whereby tissue factor (TF)-bearing microvesicles that arise from cells of monocyte/macrophage lineage can fuse with activated endothelial cells in regions of vessel activation or inflammation and initiate blood coagulation. Key components of this model include docking of the microvesicles to the stimulated endothelium through P-selectin glycoprotein ligand-1 on their surfaces binding to either P-selectin or E-selectin on the endothelium, and the role of hypoxia during blood stasis in initiating local endothelial activation. Elevations in the levels of TF-bearing microvesicles associated with inflammatory conditions would help to explain the increased risk of thrombosis associated with infections and inflammatory states such as inflammatory bowel disease. In Section II, Dr. Clive Kearon discusses the risk factors for recurrent thrombosis and strategies for determining length of therapy and tailoring specific therapies through risk stratification. Those patients who experience VTE in association with a major reversible risk factor such as surgery are much less likely to experience a recurrence when anticoagulation is discontinued than are patients with a persistent risk factor, such as thrombophilia or cancer unresponsive to therapy. Those with a minor reversible risk factor, such as prolonged air travel, have an intermediate risk of recurrence after discontinuance of anticoagulant therapy. The author provides an algorithm for using risk assessment as a means of determining the length and type of therapy to be used to minimize the rate of recurrence while simultaneously diminishing the risk of bleeding associated with anticoagulation. In Section III, Dr. Agnes Lee updates the topic of VTE associated with malignancy. Patients with cancer make up approximately 20% of those presenting with first time VTE, and the presence of VTE forebodes a much poorer prognosis for patients with cancer, likely because of the morbidity associated with VTE itself and because VTE may herald a more aggressive cancer. Recent evidence indicates that low-molecular weight heparins (LMWHs) improve survival in patients with advanced cancer through mechanisms beyond their effect as anticoagulants. Because of their improved efficacy and safety and potential anti-neoplastic effect, the LMWHs have become the anticoagulants of choice for treating VTE associated with cancer.

Heparin, Low-Molecular-Weight↗
PubMed2003

Low-molecular-weight heparin versus a coumarin for the prevention of recurrent venous thromboembolism in patients with cancer.

BACKGROUND: Patients with cancer have a substantial risk of recurrent thrombosis despite the use of oral anticoagulant therapy. We compared the efficacy of a low-molecular-weight heparin with that of an oral anticoagulant agent in preventing recurrent thrombosis in patients with cancer. METHODS: Patients with cancer who had acute, symptomatic proximal deep-vein thrombosis, pulmonary embolism, or both were randomly assigned to receive low-molecular-weight heparin (dalteparin) at a dose of 200 IU per kilogram of body weight subcutaneously once daily for five to seven days and a coumarin derivative for six months (target international normalized ratio, 2.5) or dalteparin alone for six months (200 IU per kilogram once daily for one month, followed by a daily dose of approximately 150 IU per kilogram for five months). RESULTS: During the six-month study period, 27 of 336 patients in the dalteparin group had recurrent venous thromboembolism, as compared with 53 of 336 patients in the oral-anticoagulant group (hazard ratio, 0.48; P=0.002). The probability of recurrent thromboembolism at six months was 17 percent in the oral-anticoagulant group and 9 percent in the dalteparin group. No significant difference between the dalteparin group and the oral-anticoagulant group was detected in the rate of major bleeding (6 percent and 4 percent, respectively) or any bleeding (14 percent and 19 percent, respectively). The mortality rate at six months was 39 percent in the dalteparin group and 41 percent in the oral-anticoagulant group. CONCLUSIONS: In patients with cancer and acute venous thromboembolism, dalteparin was more effective than an oral anticoagulant in reducing the risk of recurrent thromboembolism without increasing the risk of bleeding.

Acenocoumarol↗
PubMed2003

Venous thromboembolism and cancer: risks and outcomes.

Cancer and its treatments are well-recognized risk factors for venous thromboembolism (VTE). Evidence suggests that the absolute risk depends on the tumor type, the stage or extent of the cancer, and treatment with antineoplastic agents. Furthermore, age, surgery, immobilization, and other comorbid features will also influence the overall likelihood of thrombotic complications, as they do in patients without cancer. The role of hereditary thrombophilia in patients with cancer and thrombosis is still unclear, and screening for this condition in cancer patients is not indicated. The most common malignancies associated with thrombosis are those of the breast, colon, and lung, reflecting the prevalence of these malignancies in the general population. When adjusted for disease prevalence, the cancers most strongly associated with thrombotic complications are those of the pancreas, ovary, and brain. Idiopathic thrombosis can be the first manifestation of an occult malignancy. However, intensive screening for cancer in patients with VTE often does not improve survival and is not generally warranted. Independently of the timing of cancer diagnosis (before or after the VTE), the life expectancy of cancer patients with VTE is relatively short, because of both deaths from recurrent VTE and the cancer itself. Patients with cancer and acute VTE who take anticoagulants for an extended period are at increased risk of recurrent VTE and bleeding. A recent randomized trial, the Randomized Comparison of Low Molecular Weight Heparin versus Oral Anticoagulant Therapy for Long-Term Anticoagulation in Cancer Patients with Venous Thromboembolism (CLOT) study, showed that low molecular weight heparin may be a better treatment option for this group of patients. The antineoplastic effects of anticoagulants are being actively investigated with promising preliminary results.

Anticoagulants↗
PubMed2003

Epidemiology and management of venous thromboembolism in patients with cancer.

Cancer and its treatments are well-recognized risk factors for venous thromboembolism (VTE). Although the incidence of VTE in cancer patients is not well documented, there is evidence that the absolute risk depends on the tumor type, the stage or extent of the cancer, and treatment with antineoplastic agents. The most common cancer types seen in patients with thrombosis are breast, colorectal and lung, reflecting the prevalence of these malignancies in the general population. When the underlying prevalence is taken into account, cancers of the pancreas, ovary and brain are the most strongly associated with thrombotic complications. Although idiopathic thrombosis can be the first manifestation of an occult malignancy, extensive screening for cancer in these patients has not been shown to improve survival and is not warranted. Prophylaxis in patients undergoing major surgery for cancer with either unfractionated or low-molecular-weight heparin (LMWH) is strongly recommended, but prophylaxis in ambulatory medical oncology patients is not routinely indicated. Anticoagulant therapy remains the mainstay treatment of VTE in cancer patients and recent evidence shows that LMWH is effective and well tolerated for both initial therapy and secondary prophylaxis. Despite treatment, cancer patients with thrombosis have a poor prognosis. This is likely due to premature deaths from recurrent VTE and to the aggressive nature of the underlying cancer. Whether LMWH is capable of modifying tumour biology remains unanswered. Further research is needed to address the many clinical questions in the management of thrombosis in patients with cancer.

Anticoagulants↗
PubMed2003

A diagnostic strategy involving a quantitative latex D-dimer assay reliably excludes deep venous thrombosis.

BACKGROUND: Because clinical diagnosis is inaccurate, objective testing is usually considered necessary when patients present with suspected deep venous thrombosis (DVT). OBJECTIVE: To determine whether a negative result on a quantitative latex D dimer assay eliminates the need for further investigation in patients with a low or moderate pretest probability of DVT. DESIGN: Prospective cohort study. SETTING: Three tertiary care hospitals in Canada. PATIENTS: 556 consecutive outpatients with suspected first DVT. INTERVENTION: Patients were categorized as having a low, moderate, or high pretest probability of DVT and then underwent D-dimer testing. Patients with low or moderate pretest probability and a negative D-dimer result had no further diagnostic testing and received no anticoagulant therapy. Serial compression ultrasonography was performed in all other patients. Patients who did not receive a diagnosis of DVT were followed for symptomatic venous thromboembolism. MEASUREMENTS: Objectively confirmed symptomatic venous thromboembolic events during 3 months of follow-up. RESULTS: 283 patients (51%) had low or moderate pretest probability and a negative D-dimer result. One of these patients had DVT during follow-up (negative likelihood ratio, 0.05 [CI, 0.01 to 0.23]). The negative likelihood ratio of the d -dimer test in all patients was 0.03 (CI, 0.01 to 0.16). CONCLUSION: A negative result on a quantitative latex d -dimer assay safely eliminates the need for further testing in patients with low or moderate pretest probability of DVT.

Fibrin Fibrinogen Degradation Products↗
PubMed2003

The role of low-molecular-weight heparins in the prevention and treatment of venous thromboembolism in cancer patients.

Accumulating evidence suggests that low-molecular-weight heparins are the drug of choice for the prevention and treatment of venous thromboembolism in patients with cancer. For prophylaxis in the surgical setting, once-daily subcutaneous injections of low-molecular-weight heparin are as effective and safe as multiple doses of unfractionated heparin. Extending prophylaxis with low-molecular-weight heparins beyond hospitalization was recently found to reduce safely the risk of postoperative thrombosis after abdominal surgery for cancer. For the long-term treatment of deep vein thrombosis and in select patients with pulmonary embolism, recently completed clinical trials have shown that secondary prophylaxis with low-molecular-weight heparin is feasible and more effective than oral anticoagulant therapy in preventing recurrent venous thromboembolism in cancer patients. There is also evidence that low-molecular-weight heparins are effective in cancer patients who develop recurrent thrombosis while on warfarin therapy. Lastly, the potential antineoplastic effects of low-molecular-weight heparins make these agents an attractive option in patients with cancer. Although the management of cancer patients with venous thromboembolism remains challenging, low-molecular-weight heparins have simplified and improved the prevention and treatment of venous thromboembolism in these high-risk patients.

Anticoagulants↗
PubMed2003

Anti-thrombotic therapy in cancer patients.

Primary and secondary prevention of venous thromboembolism (VTE) are the major roles of anti-thrombotic therapy in patients with cancer. Although the choices of pharmacological agents remain limited, low molecular weight heparins (LMWHs) offer important advantages over traditional anticoagulants. For prophylaxis in the surgical setting, once-daily subcutaneous injections of LMWH are as effective and safe as multiple doses of unfractionated heparin and extending prophylaxis with LMWH beyond hospitalisation can safely reduce the risk of postoperative thrombosis after abdominal surgery for cancer. For treatment and secondary prophylaxis, clinical trials have shown that LMWHs are feasible, safe and more effective than oral anticoagulants in preventing recurrent VTE in cancer patients. Nonetheless, formal economic analyses are needed to study the cost-effectiveness of these agents. The preliminary observations that LMWHs are associated with reduction in cancer mortality make these agents an attractive therapeutic option in oncology patients.

Anticoagulants↗
PubMed2002

How we diagnose and treat deep vein thrombosis.

Making a diagnosis of deep vein thrombosis (DVT) requires both clinical assessment and objective testing because the clinical features are nonspecific and investigations can be either falsely positive or negative. The initial step in the diagnostic process is to stratify patients into high-, intermediate-, or low-risk categories using a validated clinical model. When the clinical probability is intermediate or high and the venous ultrasound result is positive, acute symptomatic DVT is confirmed. Similarly, when the probability is low and the ultrasound result is normal, DVT is ruled out. A low clinical probability combined with a negative D-dimer result can also be used to rule out DVT, thereby obviating the need for ultrasonography. In contrast, when the clinical assessment is discordant with the results of objective testing, serial venous ultrasonography or venography is required to confirm or refute a diagnosis of DVT. Once a patient is diagnosed with an acute DVT, low-molecular-weight heparin (LMWH) is the agent of choice for initial therapy and oral anticoagulant therapy is the standard for long-term secondary prophylaxis. Therapy should continue for at least 3 months; the decision to continue treatment beyond 3 months is made by weighing the risks of recurrent thrombosis and anticoagulant-related bleeding, and is influenced by patient preference. Screening for associated thrombophilia is not indicated routinely, but should be performed in selected patients whose clinical features suggest an underlying hypercoagulable state. Several new anticoagulants with theoretical advantages over existing agents are undergoing evaluation in phase 3 studies in patients with venous thromboembolism.

Adult↗
PubMed2002

Diagnosis and treatment of venous thromboembolism.

The diagnosis of deep vein thrombosis (DVT) and pulmonary embolism (PE) has been improved and simplified over the past decade thanks to advances in noninvasive and readily accessible technology. With high degrees of sensitivity and specificity, venous ultrasonography is favored as the initial investigation for DVT. To diagnose PE, most clinicians rely on diagnostic algorithms that combine clinical assessment, noninvasive lung studies, and, if necessary, venous ultrasonography of the legs and D-dimer testing. Substantial progress has also occurred in the treatment of acute venous thromboembolism with the introduction of low-molecular-weight heparins. This class of antithrombotic agents has changed initial therapy from an inpatient, intravenous regimen that required laborious monitoring to an outpatient practice using weight-adjusted doses of once-daily subcutaneous injections. In addition, several new anticoagulants with theoretical advantages over existing agents have entered phase III studies. Aspects of thrombosis treatment that remain controversial include vena caval interruption and the indications for thrombolysis and surgical thromboembolectomy.

Diagnostic Imaging↗