Treatment of Cancer-Associated Thrombosis: Recent Advances, Unmet Needs, and Future Direction.

Cancer-associated thrombosis, with the incidence rising over the years, is associated with significant morbidity and mortality in patients with cancer. Recent advances in the treatment of cancer-associated venous thromboembolism (VTE) include the introduction of direct oral anticoagulants (DOACs), which provide a more convenient and effective option than low-molecular-weight heparin (LMWH). Nonetheless, important unmet needs remain including an increased risk of bleeding in certain patient subgroups such as those with gastroesophageal cancer, concerns about drug-drug interactions, and management of patients with severe renal impairment. Although DOACs are more convenient than LMWH, persistence can decline over time. Factor XI inhibitors have potential safety advantages over DOACs because factor XI appears to be essential for thrombosis but not hemostasis. In phase II trials, some factor XI inhibitors were superior to enoxaparin for the prevention of VTE after knee replacement surgery without increasing the risk of bleeding. Ongoing trials are assessing the efficacy and safety of factor XI inhibitors for the treatment of cancer-associated VTE.

Genomic profiling identifies somatic mutations predicting thromboembolic risk in patients with solid tumors.

Venous thromboembolism (VTE) associated with cancer (CAT) is a well-described complication of cancer and a leading cause of death in patients with cancer. The purpose of this study was to assess potential associations of molecular signatures with CAT, including tumor-specific mutations and the presence of clonal hematopoiesis. We analyzed deep-coverage targeted DNA-sequencing data of >14 000 solid tumor samples using the Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets platform to identify somatic alterations associated with VTE. End point was defined as the first instance of cancer-associated pulmonary embolism and/or proximal/distal lower extremity deep vein thrombosis. Cause-specific Cox proportional hazards regression was used, adjusting for pertinent clinical covariates. Of 11 695 evaluable individuals, 72% had metastatic disease at time of analysis. Tumor-specific mutations in KRAS (hazard ratio [HR], 1.34; 95% confidence interval (CI), 1.09-1.64; adjusted P = .08), STK11 (HR, 2.12; 95% CI, 1.55-2.89; adjusted P < .001), KEAP1 (HR, 1.84; 95% CI, 1.21-2.79; adjusted P = .07), CTNNB1 (HR, 1.73; 95% CI, 1.15-2.60; adjusted P = .09), CDKN2B (HR, 1.45; 95% CI, 1.13-1.85; adjusted P = .07), and MET (HR, 1.83; 95% CI, 1.15-2.92; adjusted P = .09) were associated with a significantly increased risk of CAT independent of tumor type. Mutations in SETD2 were associated with a decreased risk of CAT (HR, 0.35; 95% CI, 0.16-0.79; adjusted P = .09). The presence of clonal hematopoiesis was not associated with an increased VTE rate. This is the first large-scale analysis to elucidate tumor-specific genomic events associated with CAT. Somatic tumor mutations of STK11, KRAS, CTNNB1, KEAP1, CDKN2B, and MET were associated with an increased risk of VTE in patients with solid tumors. Further analysis is needed to validate these findings and identify additional molecular signatures unique to individual tumor types.

A tumor-selective adenoviral vector platform induces transient antiphospholipid antibodies, without increased risk of thrombosis, in phase 1 clinical studies.

Tumor-selective viruses are a novel therapeutic approach for treating cancer. Tumor-Specific Immuno Gene Therapy (T-SIGn) vectors are tumor-selective adenoviral vectors designed to express immunomodulatory transgenes. Prolonged activated partial thromboplastin time (aPTT), associated with the presence of antiphospholipid antibodies (aPL), has been observed in patients with viral infections, and following administration of adenovirus-based medicines. aPL may be detected as lupus anticoagulant (LA), anti-cardiolipin (aCL) and/or anti-beta 2 glycoprotein antibodies (aß2GPI). No subtype alone is definitive for development of clinical sequalae, however, patients who are 'triple positive' have a greater thrombotic risk. Additionally, isolated aCL and aß2GPI IgM do not appear to add value in thrombotic association to aPL positivity, rather IgG subtypes must also be present to confer an increased risk. Here we report induction of prolonged aPTT and aPL in patients from eight Phase 1 studies who were treated with adenoviral vectors (n = 204). Prolonged aPTT (≥ Grade 2) was observed in 42% of patients, with a peak at 2-3 weeks post-treatment and resolution within ~ 2 months. Among patients with aPTT prolongation, LA, but not aCL IgG nor aß2GPI IgG, was observed. The transience of the prolongation and discordance between positive LA and negative aCL/aß2GPI IgG assays is not typical of a prothrombotic state. Among the patients with prolonged aPTT there was no evidence of an increased rate of thrombosis. These findings elucidate the relationship between viral exposure and aPL in the context of clinical trials. They suggest a framework in which hematologic changes can be monitored in patients receiving similar treatments.Clinical trial registration:NCT02028442, NCT02636036, NCT02028117, NCT03852511, NCT04053283, NCT05165433, NCT04830592, NCT05043714.

Occult recurrent breast cancer masquerading as thrombotic thrombocytopenic purpura.

GATA3 immunohistochemistry stain of the bone marrow biopsy required to diagnose recurrent metastatic breast cancer.

Rivaroxaban for Thromboprophylaxis in High-Risk Ambulatory Patients with Cancer.

BACKGROUND: Ambulatory patients receiving systemic cancer therapy are at varying risk for venous thromboembolism. However, the benefit of thromboprophylaxis in these patients is uncertain. METHODS: In this double-blind, randomized trial involving high-risk ambulatory patients with cancer (Khorana score of ≥2, on a scale from 0 to 6, with higher scores indicating a higher risk of venous thromboembolism), we randomly assigned patients without deep-vein thrombosis at screening to receive rivaroxaban (at a dose of 10 mg) or placebo daily for up to 180 days, with screening every 8 weeks. The primary efficacy end point was a composite of objectively confirmed proximal deep-vein thrombosis in a lower limb, pulmonary embolism, symptomatic deep-vein thrombosis in an upper limb or distal deep-vein thrombosis in a lower limb, and death from venous thromboembolism and was assessed up to day 180. In a prespecified supportive analysis involving the same population, the same end point was assessed during the intervention period (first receipt of trial agent to last dose plus 2 days). The primary safety end point was major bleeding. RESULTS: Of 1080 enrolled patients, 49 (4.5%) had thrombosis at screening and did not undergo randomization. Of the 841 patients who underwent randomization, the primary end point occurred in 25 of 420 patients (6.0%) in the rivaroxaban group and in 37 of 421 (8.8%) in the placebo group (hazard ratio, 0.66; 95% confidence interval [CI], 0.40 to 1.09; P = 0.10) in the period up to day 180. In the prespecified intervention-period analysis, the primary end point occurred in 11 patients (2.6%) in the rivaroxaban group and in 27 (6.4%) in the placebo group (hazard ratio, 0.40; 95% CI, 0.20 to 0.80). Major bleeding occurred in 8 of 405 patients (2.0%) in the rivaroxaban group and in 4 of 404 (1.0%) in the placebo group (hazard ratio, 1.96; 95% CI, 0.59 to 6.49). CONCLUSIONS: In high-risk ambulatory patients with cancer, treatment with rivaroxaban did not result in a significantly lower incidence of venous thromboembolism or death due to venous thromboembolism in the 180-day trial period. During the intervention period, rivaroxaban led to a substantially lower incidence of such events, with a low incidence of major bleeding. (Funded by Janssen and others; CASSINI ClinicalTrials.gov number, NCT02555878.).

Mechanisms of Ischemic Stroke in Patients with Cancer: A Prospective Study.

OBJECTIVE: The objective of this study was to examine the pathophysiology of ischemic stroke with cancer. METHODS: We conducted a prospective cross-sectional study from 2016 to 2020 at 2 hospitals. We enrolled 3 groups of 50 adult participants each. The main group included patients with active solid tumor cancer and acute ischemic stroke. The control groups included patients with acute ischemic stroke only or active cancer only. The patients with stroke-only and patients with cancer-only were matched to the patients with cancer-plus-stroke by age, sex, and cancer type, if applicable. The outcomes were prespecified hematological biomarkers and transcranial Doppler microemboli detection. Hematological biomarkers included markers of coagulation (D-dimer and thrombin-antithrombin), platelet function (P-selectin), and endothelial integrity (thrombomodulin, soluble intercellular adhesion molecule-1 [sICAM-1], and soluble vascular cell adhesion molecule-1 [sVCAM-1]). Hematological biomarkers were compared between groups using the Kruskal-Wallis and Wilcoxon Rank-Sum tests. In multivariable linear regression models, we adjusted for race, number of stroke risk factors, smoking, stroke severity, and antithrombotic use. Transcranial Doppler microemboli presence was compared between groups using chi-square tests. RESULTS: Levels of all study biomarkers were different between groups. In univariate between-group comparisons, patients with cancer-plus-stroke had higher levels of D-dimer, sICAM-1, sVCAM-1, and thrombomodulin than both control groups; higher levels of thrombin-antithrombin than patients with cancer-only; and higher levels of P-selectin than patients with stroke-only. Findings were similar in multivariable analyses. Transcranial Doppler microemboli were detected in 32% of patients with cancer-plus-stroke, 16% of patients with stroke-only, and 6% of patients with cancer-only (p = 0.005). INTERPRETATION: Patients with cancer-related stroke have higher markers of coagulation, platelet, and endothelial dysfunction, and more circulating microemboli, than matched controls. ANN NEUROL 2021;90:159-169.

Chemotherapy-induced thrombocytopenia in pediatric oncology: Scope of the problem and opportunities for intervention.

BACKGROUND: Chemotherapy-induced thrombocytopenia (CIT) is a known hematologic complication of oncology treatment. This single-institution study examines the degree with which CIT impacts specific pediatric solid tumor cohorts reflected by platelet transfusion burden and treatment modifications. PROCEDURE: Data regarding clinically relevant CIT were obtained via a retrospective chart review of pediatric solid tumor patients treated at Memorial Sloan Kettering Cancer Center from 2013 to 2020. Patients were stratified based on histologic diagnoses as well as chemotherapy regimen. CIT impact was assessed through platelet transfusion means, chemotherapy dose reductions, and treatment delays. RESULTS: A total of 150 patients were included with mean age 10.3 [0.2-21.0]. Patients receiving therapy for high-risk neuroblastoma and localized Ewing sarcoma, both of which included high-dose cyclophosphamide and doxorubicin, required the most platelet transfusions over the treatment course, with a mean of 13 and 9, respectively. Reduced relative dose intensity (RDI), due in part to CIT, was greatest for the patients receiving therapy for high-risk and intermediate-risk rhabdomyosarcoma. Fifty-six percent of high-risk patients experienced a reduced RDI during the final two cycles of treatment and 69% of intermediate-risk patients experienced one during the final four cycles of treatment. CONCLUSIONS: The impact of CIT varied by the administered chemotherapy regimens and dose intensity of chemotherapy agents. This study demonstrated that CIT causes both marked platelet transfusion burden as well as treatment reduction and delay within certain solid tumor cohorts. This can lend to future studies aimed at reducing the burden of CIT and targeting the most at-risk populations.

Approach to Cancer-Associated Thrombosis: Challenging Situations and Knowledge Gaps.

Malignancy is a significant risk factor for venous thromboembolism (VTE). It is estimated that up to 20% of patients with cancer may develop VTE at some time in their cancer journey. Cancer-associated VTE can lead to hospitalizations, morbidity, delayed cancer treatment, and mortality. The optimal prevention and management of cancer-associated thrombosis (CAT) is of utmost importance. Direct oral anticoagulants have been recommended as first-line therapy for VTE treatment in the general population and their efficacy has recently been demonstrated in the cancer population, leading to increased use. However, patients with cancer have unique challenges and comorbidities that can lead to increased risks and concerns with anticoagulation. Herein we will discuss commonly encountered challenges in patients with CAT, review available literature, and provide practice suggestions. IMPLICATIONS FOR PRACTICE: This article aims to specifically address cancer-associated thrombosis issues for which there is limited or absent evidence to guide best practice, for circumstances that pose unique challenges for clinicians, and for directions when the literature is conflicting. It reviews pertinent data for each selected topic and provides guidance for patient management based on the best available evidence and experiences from the panel.

Risk of venous thromboembolism in ovarian cancer patients receiving neoadjuvant chemotherapy.

PURPOSE: To determine the incidence of venous thromboembolism (VTE) and define clinical risk factors associated with the development of new-onset VTE in patients receiving neoadjuvant chemotherapy (NACT) for ovarian cancer (OC). METHODS: An institutional ovarian cancer database was used to identify all OC patients receiving NACT from 04/2015-09/2018. VTE events were recorded and included clinically diagnosed deep venous thrombosis (DVT) and/or pulmonary embolism (PE). The incidence of VTE events was categorized according to treatment phases (P): P0) First visit/prior to induction of NACT; P1) during NACT before interval debulking surgery (IDS); P2) intraoperative through day 28 post-IDS; P3) during adjuvant chemotherapy. RESULTS: A total of 290 patients were identified during the study period. Seventy-five (25.9%) developed a VTE at some point from time of presentation through the peri-operative period. Forty (13.8%) presented with VTE prior to initiation of NACT. An additional 27 (11.6%) developed a VTE during NACT (P1); 6 (3.9%) during the intraoperative and 28-day post-operative period (P2); and 2 (1.3%) during the adjuvant period (P3). The overall VTE rate was 25.9% (n = 75). FIGO stage IV disease was the only factor associated with increased risk for a new-onset VTE [Odds Ratio (OR): 3.9 (95% Confidence Interval [CI] = 1.2-13.6; p = 0.03]. CONCLUSIONS: Patients receiving NACT for advanced OC are at extremely high risk for developing thromboembolic events, either at initial presentation or during induction of NACT, a treatment phase that is traditionally without use of prophylactic anticoagulation. Since Khorana scoring is not predictive in this population, clinicians might need to consider increased screening or use of prophylactic anticoagulation in patients receiving NACT for OC, particularly in advanced metastatic disease.

The incidence of thrombocytopenia in adult patients receiving chemotherapy for solid tumors or hematologic malignancies.

OBJECTIVES: To estimate the risk of thrombocytopenia in various cancers and chemotherapy regimens. METHODS: Structured patient-level data from the Flatiron Health Electronic Health Record database were used to identify adult patients who received chemotherapy for a solid tumor or hematologic malignancy from 2012 to 2017. Three-month cumulative incidence of thrombocytopenia was assessed based on platelet counts, overall and by grade of thrombocytopenia. Co-occurrence of anemia, neutropenia, and leukopenia was evaluated. RESULTS: Of 15,521 patients with solid tumors, 13% had thrombocytopenia within 3 months (platelet count < 100 × 109 /L); 4% had grade 3 (25 to < 50 × 109 /L), and 2% grade 4 (<25 × 109 /L) thrombocytopenia. Of 2537 patients with hematologic malignancies, 28% had any thrombocytopenia, 16% with grade 3, and 12% with grade 4. Among patients with thrombocytopenia, it occurred without another cytopenia in 18% of solid tumors and 7% of hematologic malignancies. CONCLUSIONS: In a large, US-representative sample of patients undergoing chemotherapy in clinical practice, thrombocytopenia incidence varied across tumor and regimen types. Despite recommendations to alter chemotherapy to avoid severe thrombocytopenia, 4% of patients with solid tumors and 16% with hematologic malignancies experienced grade 3 thrombocytopenia. Prediction and prevention of thrombocytopenia may help oncologists avoid dose modifications and their adverse effects on survival.

Use of Direct Oral Anticoagulants for Treating Venous Thromboembolism in Patients With Cancer.

For patients with cancer who experience venous thromboembolism (VTE), low-molecular-weight heparin (LMWH) remains the standard of care in the NCCN Guidelines for VTE, but under certain conditions direct oral anticoagulants (DOACs) are acceptable alternatives. A growing body of literature suggests that DOACs may more effective than LMWHs in preventing recurrences, but they do carry some increased risk of bleeding. Most of this risk is seen in patients with gastrointestinal or urinary pathology or implanted devices. DOACs are also acceptable when the pain, cost, and inconvenience of LMWHs are expected to be obstacles to compliance. Through careful patient selection, most patients can be treated successfully with a DOAC, although for most patients with gastrointestinal or urinary pathology, LMWH remains the safer choice.

Enoxaparin dose reduction for thrombocytopenia in patients with cancer: a quality assessment study.

The development of thrombocytopenia in the setting of therapeutic anticoagulation for venous thromboembolic disease (VTE) is common in cancer patients, but guidelines for management are based on limited past data and have not been validated. In 2011, Memorial Sloan Kettering Cancer Center (MSKCC) implemented the following guidelines in this setting: administer full dose enoxaparin for a platelet count > 50,000/mcL, half-dose enoxaparin for a platelet count of 25,000-50,000/mcL, and hold anticoagulation for a platelet count < 25,000/mcL. We now report validation of safety and efficacy of these guidelines. As a Quality Assessment Initiative, we evaluated our guidelines for adult cancer patients at MSKCC who were on therapeutic-dose enoxaparin for VTE during the years 2011 through 2013 and experienced at least one 7-day period of thrombocytopenia (platelet count ≤ 50,000/mcL). We assessed adherence to the enoxaparin dose modification guidelines, major bleeding, clinically relevant non-major bleeding, recurrent VTE, and mortality during the thrombocytopenic episodes. We identified 99 patients with 140 episodes of thrombocytopenia of 7 or more days. The median duration of these thrombocytopenic episodes was 12 days. The enoxaparin dose was modified in 133 of the 140 episodes (95%), reflecting satisfactory adherence to our institutional guidelines. There were no recurrent VTE events or major bleeding episodes when the anticoagulant dose was reduced or held. In this cohort, there was only one major bleeding episode, a trauma-associated retroperitoneal hemorrhage that occurred on the third day of a thrombocytopenic episode, prior to enoxaparin dose modification. There were 13 clinically relevant non-major bleeding episodes. Lastly, 10 patients died of cancer-related causes during an episode of thrombocytopenia. This Quality Assessment Initiative supports the safety and efficacy of our guidelines for therapeutic enoxaparin dose modification.

Safe and effective use of rivaroxaban for treatment of cancer-associated venous thromboembolic disease: a prospective cohort study.

Low-molecular weight heparin (LMWH) has been the standard of care for treatment of venous thromboembolism (VTE) in patients with cancer. Rivaroxaban was approved in 2012 for the treatment of pulmonary embolism (PE) and deep vein thrombosis (DVT), but no prior studies have been reported specifically evaluating the efficacy and safety of rivaroxaban for cancer-associated thrombosis (CAT). Under a Quality Assessment Initiative (QAI), we established a Clinical Pathway to guide rivaroxaban use for CAT and now report a validation analysis of our first 200 patients. A 200 patient cohort with CAT (PE or symptomatic, proximal DVT), whose full course of anticoagulation was with rivaroxaban, were accrued. In competing risk analysis, primary endpoints at 6 months included new or recurrent PE or symptomatic proximal lower extremity DVT, major bleeding, clinically-relevant non-major bleeding leading to discontinuation of rivaroxaban, or death. In competing risk analysis, the 6 months cumulative incidence of new or recurrent VTE was 4.4 % (95 % CI = 1.4-7.4 %), major bleeding was 2.2 % (95 % CI = 0-4.2 %) and all-cause mortality 17.6 % (95 % CI = 11.7-23.0 %). In this cohort of 200 patients with active cancer and CAT the rates of new or recurrent VTE and major bleeding were comparable to the cancer subgroup analysis from the EINSTEIN studies. The results of our Clinical Pathway provide guidance on Rivaroxaban use for treatment of CAT, and suggest that safety and efficacy is preserved, compared with past-published experience with LMWH.

What's new in the pathogenesis of the coagulopathy in acute promyelocytic leukemia?

PURPOSE OF REVIEW: Acute promyelocytic leukemia (APL) is associated with a complex coagulopathy. In spite of substantial recent improvements in treatment regimens, hemorrhagic death remains the main cause of induction failure. In this review, we delineate recent understanding of the pathophysiology and management of the hemorrhagic diathesis of APL. RECENT FINDINGS: Laboratory and clinical data suggest that the malignant leukocytes mediate the hemorrhagic diathesis associated with APL through multiple mechanisms which lead to a combination of consumptive coagulopathy and primary hyperfibrinolysis. Exposure of tissue factor and Annexin II by the leukemic blasts is the main determinants of these processes. Promyelocyte-derived microparticles have recently been implicated in the coagulopathy as well. Total white cell count and platelet count have emerged as good general predictors of hemorrhagic death, along with the different routine hemostatic parameters. Prompt treatment with all-trans retinoic acid, with or without arsenic trioxide, is the most important step in preventing bleeding complications. Repletion of coagulation factors and platelets with blood products remains the mainstay of supportive treatment, whereas the role of recombinant soluble thrombomodulin is currently being investigated. SUMMARY: The coagulopathy of APL is multifactorial, with both disseminated intravascular coagulation and primary hyperfibrinolysis mediated largely by the malignant leukocytes.

Alternatively spliced tissue factor promotes plaque angiogenesis through the activation of hypoxia-inducible factor-1α and vascular endothelial growth factor signaling.

BACKGROUND: Alternatively spliced tissue factor (asTF) is a novel isoform of full-length tissue factor, which exhibits angiogenic activity. Although asTF has been detected in human plaques, it is unknown whether its expression in atherosclerosis causes increased neovascularization and an advanced plaque phenotype. METHODS AND RESULTS: Carotid (n=10) and coronary (n=8) specimens from patients with stable or unstable angina were classified as complicated or uncomplicated on the basis of plaque morphology. Analysis of asTF expression and cell type-specific expression revealed a strong expression and colocalization of asTF with macrophages and neovessels within complicated, but not uncomplicated, human plaques. Our results showed that the angiogenic activity of asTF is mediated via hypoxia-inducible factor-1α upregulation through integrins and activation of phosphatidylinositol-3-kinase/Akt and mitogen-activated protein kinase pathways. Hypoxia-inducible factor-1α upregulation by asTF also was associated with increased vascular endothelial growth factor expression in primary human endothelial cells, and vascular endothelial growth factor-Trap significantly reduced the angiogenic effect of asTF in vivo. Furthermore, asTF gene transfer significantly increased neointima formation and neovascularization after carotid wire injury in ApoE(-/-) mice. CONCLUSIONS: The results of this study provide strong evidence that asTF promotes neointima formation and angiogenesis in an experimental model of accelerated atherosclerosis. Here, we demonstrate that the angiogenic effect of asTF is mediated via the activation of the hypoxia-inducible factor-1/vascular endothelial growth factor signaling. This mechanism may be relevant to neovascularization and the progression and associated complications of human atherosclerosis as suggested by the increased expression of asTF in complicated versus uncomplicated human carotid and coronary plaques.

Ovarian vein thrombosis after debulking surgery for ovarian cancer: epidemiology and clinical significance.

OBJECTIVE: Ovarian vein thrombosis is associated with pregnancy and pelvic surgery. Postpartum ovarian vein thrombosis is associated with infection and a high morbidity rate and is treated with anticoagulant and intravenous antibiotic therapy. The natural history of such thrombotic events after debulking surgery for ovarian cancer has not been well described. Our objective was to characterize the presentation and outcomes for patients with this condition at our institution. STUDY DESIGN: We conducted a retrospective study of patients who underwent surgical debulking for ovarian cancer at Memorial Sloan Kettering Cancer Center between the years 2001 and 2010. Patients were included if contrast computed tomography scans of both the abdomen and pelvis were performed within 12 weeks before and 12 weeks after the surgery. The images were reviewed to assess for the presence and extent of a new postoperative ovarian vein thrombosis. When available, subsequent studies were assessed for thrombus progression. Medical records were reviewed to determine whether anticoagulation was used for treatment of the thrombotic episode and to record the occurrence of any new significant venous thromboembolic event in the next year. RESULTS: One hundred fifty-nine patients had satisfactory imaging. New ovarian vein thrombosis was a common complication of debulking surgery, as found in 41 of patients (25.8%). Only 5 women with ovarian vein thrombosis were started on anticoagulation, of which 2 individuals had an independent venous thromboembolic event as indication for treatment. Only 2 of the ovarian vein thromboses (4.9%) progressed to the inferior vena cava or left renal vein on subsequent scan. The estimated cumulative incidence of venous thromboembolism 1 year after the first postoperative scan was 17.1% for patients in the new ovarian vein thrombosis group vs 15.3% of individuals for the group without a postoperative ovarian vein thrombosis (P = .78). CONCLUSION: Ovarian vein thrombosis is commonly encountered after debulking surgery for ovarian cancer. Anticoagulation is usually not indicated, and clinically meaningful thrombus progression rarely occurs.

Cancer-Associated Thrombosis: Management of a Patient With an Isolated Calf Deep Vein Thrombosis.

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology, to patients seen in their own clinical practice.Venous thromboembolism occurs frequently in patients with cancer and is the second leading cause of death, after the cancer itself. There is a well-established consensus of the need for anticoagulation in patients with a proximal deep vein thrombosis or pulmonary embolism. But with improved imaging technology and widescale use of contrast imaging for cancer staging, many incidental pulmonary emboli are detected in patients with cancer. Furthermore, many isolated distal deep vein thromboses and subsegmental pulmonary emboli are identified. There have been questions if these small or asymptomatic thromboses require anticoagulation management similar to more proximal or symptomatic thromboses. In this Oncology Grand Rounds, we will review the existing evidence for these situations. We will also review management strategies for cancer-associated thrombosis, reflecting the evolving drugs and evidence over the past 20 years.