Unanswered questions in cancer-associated thrombosis

Underlying Mechanisms of Thrombosis Associated with Cancer and Anticancer Therapies

OPINION STATEMENT

Cancer-associated thrombosis (CAT) has been identified as the second most prevalent cause of death after cancer itself. Moreover, the risk of thrombotic events in cancer patients increases due to anticancer drugs, such as tyrosine kinase inhibitors (TKIs). Venous thromboembolism (VTE) as well as arterial thromboembolic (ATE) events are present in CAT. Although VTE occurs more frequently, ATE events are very significant and in some cases are more dangerous than VTE. Guidelines for preventing thrombosis refer mainly VTE as well as the contribution of ATE events. Several factors are involved in thrombosis related to cancer, but the whole pathomechanism of thrombosis is not clear and may differ between patients. The activation of the coagulation system and the interaction of cancer cells with other cells including platelets, endothelial cells, monocytes, and neutrophils are promoted by a hypercoagulable state caused by cancer. We present an update on the pathomechanisms of CAT and the effect of anticancer drugs, mainly targeted therapies with a focus on TKIs. Considering the risk of bleeding associated with anticoagulation in each cancer patient, the anticoagulation strategy may involve the use of FXIa inhibitors, direct oral anticoagulants, and low-molecular-weight heparin. Further research would be valuable in developing strategies for reducing CAT.

Gynecological Cancer and Venous Thromboembolism: A Narrative Review to Increase Awareness and Improve Risk Assessment and Prevention

The prevention and appropriate management of venous thromboembolism in cancer patients is of paramount importance. However, the literature data report an underestimation of this major problem in patients with gynecological cancers, with an inconsistent venous thromboembolism risk assessment and prophylaxis in this patient setting. This narrative review provides a comprehensive overview of the available evidence regarding the management of venous thromboembolism in cancer patients, focusing on the specific context of gynecological tumors, exploring the literature discussing risk factors, risk assessment, and pharmacological prophylaxis. We found that the current understanding and management of venous thromboembolism in gynecological malignancy is largely based on studies on solid cancers in general. Hence, further, larger, and well-designed research in this area is needed.

[Translation into French and republication of: "Recurrent venous thromboembolism in anticoagulated cancer patients: diagnosis and treatment"]

Patients with cancer are at significantly increased risk of venous thromboembolism (VTE), due both to the impact of malignant disease itself and to the impact of certain anticancer drugs on haemostasis. This is true both for first episode venous thromboembolism and recurrence. The diagnosis and management of VTE recurrence in patients with cancer poses particular challenges, and these are reviewed in the present article, based on a systematic review of the relevant scientific literature published over the last decade. Furthermore, it is uncertain whether diagnostic algorithms for venous thromboembolism, validated principally in untreated non-cancer patients, are also valid in anticoagulated cancer patients: the available data suggests that clinical decision rules and D-dimer testing perform less well in this clinical setting. In patients with cancer, computed tomography pulmonary angiography and venous ultrasound appear to be the most reliable diagnostic tools for diagnosis of pulmonary embolism and deep vein thrombosis respectively. Options for treatment of venous thromboembolism include low molecular weight heparins (at a therapeutic dose or an increased dose), fondaparinux or oral direct factor Xa inhibitors. The choice of treatment should take into account the nature (pulmonary embolism or VTE) and severity of the recurrent event, the associated bleeding risk, the current anticoagulant treatment (type, dose, adherence and possible drug-drug interactions) and cancer progression.

Research progress on venous thrombosis development in patients with malignant tumors

The coexistence of venous thromboembolism (VTE) within patients with cancer, known as cancer-associated thrombosis (CAT), stands as a prominent cause of mortality in this population. Over recent years, the incidence of VTE has demonstrated a steady increase across diverse tumor types, influenced by several factors such as patient management, tumor-specific risks, and treatment-related aspects. Furthermore, mutations in specific genes have been identified as potential contributors to increased CAT occurrence in particular cancer subtypes. We conducted an extensive review encompassing pivotal historical and ongoing studies on CAT. This review elucidates the risks, mechanisms, reliable markers, and risk assessment methodologies that can significantly guide effective interventions in clinical practice.

Anticoagulation in venous thromboembolism for the general physician

Venous thromboembolism (VTE) is frequently encountered across various specialties. The management of VTE has become more nuanced, requiring consideration of several factors when deciding on the choice and duration of anticoagulation. This evidence-based review article summarises the current practice and evidence behind anticoagulation in VTE, incorporating national and international guidelines. Factors influencing decision-making around the choice and duration of anticoagulation, along with special circumstances such as cancer and antiphospholipid syndrome, are discussed. The clinical utility of thrombophilia screening is also addressed.

Oral Anticoagulants Beyond Warfarin

Direct oral anticoagulants (DOACs) have largely replaced vitamin K antagonists, mostly warfarin, for the main indications for oral anticoagulation, prevention and treatment of venous thromboembolism, and prevention of embolic stroke in atrial fibrillation. While DOACs offer practical, fixed-dose anticoagulation in many patients, specific restrictions or contraindications may apply. DOACs are not sufficiently effective in high-thrombotic risk conditions such as antiphospholipid syndrome and mechanical heart valves. Patients with cancer-associated thrombosis may benefit from DOACs, but the bleeding risk, particularly in those with gastrointestinal or urogenital tumors, must be carefully weighed. In patients with frailty, excess body weight, and/or moderate-to-severe chronic kidney disease, DOACs must be cautiously administered and may require laboratory monitoring. Reversal agents have been developed and approved for life-threatening bleeding. In addition, the clinical testing of potentially safer anticoagulants such as factor XI(a) inhibitors is important to further optimize anticoagulant therapy in an increasingly elderly and frail population worldwide.

Recurrent venous thromboembolism in anticoagulated cancer patients: Diagnosis and treatment

Patients with cancer are at significantly increased risk of venous thromboembolism (VTE), due both to the impact of malignant disease itself and to the impact of certain anticancer drugs on haemostasis. This is true both for first episode venous thromboembolism and recurrence. The diagnosis and management of VTE recurrence in patients with cancer poses particular challenges, and these are reviewed in the present article, based on a systematic review of the relevant scientific literature published over the last decade. Furthermore, it is uncertain whether diagnostic algorithms for venous thromboembolism, validated principally in untreated non-cancer patients, are also valid in anticoagulated cancer patients: the available data suggests that clinical decision rules and D-dimer testing perform less well in this clinical setting. In patients with cancer, computed tomography pulmonary angiography and venous ultrasound appear to be the most reliable diagnostic tools for diagnosis of pulmonary embolism and deep vein thrombosis respectively. Options for treatment of venous thromboembolism include low molecular weight heparins (at a therapeutic dose or an increased dose), fondaparinux or oral direct factor Xa inhibitors. The choice of treatment should take into account the nature (pulmonary embolism or VTE) and severity of the recurrent event, the associated bleeding risk, the current anticoagulant treatment (type, dose, adherence and possible drug-drug interactions) and cancer progression.

Effect of factor XI inhibition on tumor cell-induced coagulation activation

BACKGROUND

Cancer-associated thrombosis is a frequent complication in patients with malignancies. While factor XI (FXI)/FXIa inhibition is efficacious in preventing postoperative venous thromboembolism, its role in tumor cell-induced coagulation is less defined.

OBJECTIVES

We thus aimed to provide mechanistic insights into FXI/FXIa inhibition in tumor cell-induced coagulation activation.

METHODS

Procoagulant activity (PCA) of 4 different tissue factor (TF) expressing tumor cell lines was analyzed by single-stage clotting and thrombin generation assay in the presence of a FXIa inhibitor, BMS-262084 (BMS), an inhibitory FXI antibody (anti-FXI), or peak and trough concentrations of rivaroxaban or tinzaparin. Further, tumor cell-induced platelet aggregation was recorded. Recombinant human TF served as positive control.

RESULTS

Although BMS and anti-FXI potently inhibited FXIa amidolytic activity, both inhibitors efficiently mitigated recombinant human TF- and tumor cell-induced fibrin clot formation and platelet aggregation only in the presence of low TF PCA. The anticoagulant effects showed an inverse correlation with the magnitude of cellular TF PCA expression. Similarly, BMS markedly interfered with tumor cell-induced thrombin generation, with the most prominent effects on peak and total thrombin. In addition, anticoagulant effects of FXIa inhibition by 10 μM BMS were in a similar range to those obtained by 600 nM rivaroxaban and 1.6 μM tinzaparin at low TF PCA levels. However, rivaroxaban and tinzaparin also exerted marked anticoagulant activity at high TF PCA levels.

CONCLUSION

Our findings indicate that FXI/FXIa inhibition interferes with tumor cell-induced coagulation activation only at low TF PCA expression levels, a finding with potential implications for future in vivo studies.

Intensify Standardized Anticoagulation for Cancer-associated Pulmonary Embolism: From Single-center Real-world Data

PURPOSE

Pulmonary embolism (PE) is a significant contributor to mortality in patients with cancer. Although anticoagulation serves as the cornerstone of treatment for cancer-associated PE, it has not been emphasized in real-world settings. The aim of this study was to examine the impact of suboptimal anticoagulant treatment on the prognosis of cancer-associated PE.

METHODS

A cohort of 356 individuals newly diagnosed with acute PE were enrolled. The primary outcome of the study was recurrent venous thromboembolism (VTE), and the secondary outcomes were all-cause mortality and major bleeding (consisting of a reduction in the hemoglobin level by at least 20 g/L, transfusion of at least 2 units of blood, or symptomatic bleeding in a critical area or organ or fatal bleeding).

FINDINGS

Of the total participants, 156 (43.8%) were diagnosed with cancer. A comparison between the cancer and noncancer groups revealed that patients with cancer were more frequently asymptomatic (41.0% vs 4.5%; P < 0.001), less likely to have right ventricular dysfunction (4.5% vs 14.0%; P = 0.001), received less anticoagulant treatment during hospitalization (85.3% vs 98.5%; P < 0.001), and had a shorter duration of anticoagulation (5.02 [7.40] months vs 14.19 [10.65] months; P < 0.001). In addition, patients with cancer were found to be at a higher risk of recurrent VTE (17.3% vs 4.0%; P < 0.001) and all-cause mortality (23.7% vs 10.5%; P = 0.001). Multiple Cox regression analysis indicated that discontinuation of anticoagulation at 3 months was a significant risk factor for recurrent VTE in the cancer group (HR, 15.815; 95% CI, 3.047-82.079; P = 0.001).

IMPLICATIONS

The brief duration of anticoagulation therapy and elevated likelihood of recurrent VTE serve as cautionary indicators for the need to enhance awareness of standardized anticoagulant treatment for cancer-associated PE. The ultimate goal is to enhance patient prognosis and quality of life.

[Recommendations for thromboembolic disease in oncological processes. A view from primary care]

Venous thromboembolic disease (VTE) is a frequent complication in patients diagnosed with cancer and a cause of morbidity and mortality. Approximately 20% of thromboembolic episodes develop in association with active cancer. On the other hand, it is estimated that about 2-12% of cases, the thromboembolic episode is the first manifestation of an occult cancer, diagnosed at that time or subsequently, which offers an opportunity for early diagnosis and treatment. There are multiple factors that contribute to increase the risk of VTE in oncological patients in relation to specific characteristics of the patient, the tumor and the treatments. Knowledge of these risk factors will contribute to early diagnosis when signs of VTE appear, as well as the assessment of thromboprophylaxis if indicated. The diagnosis of VTE in patients with cancer does not differ of those who do not suffer from it. Regarding the treatment of VTE in these patients, low molecular weight heparin (LMWH), direct acting anticoagulants (DACs) and antivitamin K (VKA) are the most commonly used, although the dosing regimen and length are not clear yet. The management of these patients should be interdisciplinary and early, so the primary care physician plays a key role in this process as he/she is liaise with his/her patients. It is also necessary to update knowledge in order to improve the care of these patients. For these reasons, this document has been prepared by the Working Group on Vasculopathies of the Spanish Society of Primary Care Physicians (SEMERGEN) whose objective is to present the available information regarding the management of VTE that may appear in oncological patients, as well as the assessment of thromboprophylaxis and treatment, if appropriate, from an approach focused on a primary care field.

Awareness of venous thromboembolism among patients with cancer: Preliminary findings from a global initiative for World Thrombosis Day

BACKGROUND

Cancer-associated venous thromboembolism (CAT) has detrimental impact on patients' clinical outcomes and quality of life. Data on CAT education, communication, and awareness among the general cancer population are scanty.

METHODS

We present the preliminary results of an ongoing patient-centered survey including 27 items covering major spheres of CAT. The survey, available in 14 languages, was promoted and disseminated online through social networks, email newsletters, websites, and media.

RESULTS

As of September 20, 2022, 749 participants from 27 countries completed the survey. Overall, 61.8% (n = 460) of responders were not aware of their risk of CAT. Among those who received information on CAT, 26.2% (n = 56) were informed only at the time of CAT diagnosis. Over two thirds (69.1%, n = 501) of participants received no education on signs and symptoms of venous thromboembolism (VTE); among those who were educated about the possible clinical manifestations, 58.9% (n = 119) were given instructions to seek consultation in case of VTE suspicion. Two hundred twenty-four respondents (30.9%) had a chance to discuss the potential use of primary thromboprophylaxis with health-care providers. Just over half (58.7%, n = 309) were unaware of the risks of bleeding associated with anticoagulation, despite being involved in anticoagulant-related discussions or exposed to anticoagulants. Most responders (85%, n = 612) valued receiving CAT education as highly relevant; however, 51.7% (n = 375) expressed concerns about insufficient time spent and clarity of education received.

CONCLUSIONS

This ongoing survey involving cancer patients with diverse ethnic, cultural, and geographical backgrounds highlights important patient knowledge gaps. These findings warrant urgent interventions to improve education and awareness, and reduce CAT burden.

Oral Squamous Cell Carcinoma-Associated Thrombosis: What Evidence?

Venous thromboembolism (VTE) disease is the second leading cause of mortality in cancer patients. In the general population, the annual incidence of a thromboembolic event is about 117 cases per 100,000 persons, but cancer increases this risk about fourfold, while in patients receiving chemotherapy and surgical treatment, it is about sevenfold. Oral squamous cell carcinoma (OSCC) is the most common form of oral cancer and represents a multistep process in which environmental factors and genetic alterations are implicated. Thrombotic risk is considered empirically low in OSCC patients, although few data are available. Having limited information available may result in poor awareness of VTE prevention in OSCC, risking jeopardising the oncologic treatment and increasing the morbidity and mortality among these patients. In this paper, the topic of OSCC-associated thrombosis will be discussed.

Multidisciplinary Care for the Prevention and Treatment of Venous Thromboembolism in Patients with Cancer-Associated Thrombosis (CAT): Impact of Educational Interventions on CAT-Related Events and on Patients' and Clinicians' Awareness

Cancer is a leading cause of death. Venous thromboembolism (VTE) is an often-overlooked cause of morbidity and mortality in cancer patients that can be readily prevented and treated. Actions are needed to reduce the morbidity and mortality of patients with cancer-associated thrombosis (CAT). There is a need to increase awareness of the impact of CAT on cancer patients' morbidity and mortality, on their quality of life and to understand the importance of more effective preventions and treatments of VTE in cancer patients. Moreover, it is of great importance to systematically assess the risk of VTE in regard to patients, cancer and treatment-related factors. Unfortunately, there are unmet clinical needs in the prevention and treatment of cancer-associated VTE. In this review, we discuss an action plan to ensure an increased awareness of and education on the issues that need to be addressed in order to improve the provision of appropriate prevention, early diagnosis and effective and safe treatment of VTE to all cancer patients and, ultimately, to reduce morbidity and mortality.

Direct Oral Anticoagulants for the Prevention and Acute Treatment of Cancer-Associated Thrombosis

Cancer is a major risk factor for venous thromboembolism (VTE), and cancer-associated thrombosis (CAT) constitutes approximately 15-25% of all VTE cases. For decades, the standard treatment for CAT used to be daily subcutaneous low molecular weight heparin (LMWH). Data on the safety and efficacy of the direct oral anticoagulants (DOACs) in this population emerged only in recent years and specific DOACs were included into recent guidelines recommendations. In this narrative review of the literature, we reported the results of the phase III randomized controlled trials that evaluated the DOACs for the prevention and the acute treatment of CAT. For the acute phase treatment, the anti-Xa inhibitors (apixaban, edoxaban, rivaroxaban) showed better efficacy than LMWH in preventing VTE recurrence; however, rivaroxaban and edoxaban were also associated with an increased risk of bleeding events. For primary prevention of CAT in ambulatory cancer patients starting chemotherapy, apixaban and rivaroxaban showed better efficacy than placebo but a trend towards higher bleeding rates. Recent guidelines suggest the DOACs for the treatment of CAT in selected cancer patients (eg, low bleeding risk, no luminal gastrointestinal or genitourinary malignancies, no interfering medications). The DOACs are also suggested for primary thromboprophylaxis in selected ambulatory cancer patients at high risk of VTE (eg, Khorana score ≥2 prior to starting new chemotherapy, low bleeding risk, no interfering medications).