Primary prophylaxis for venous thromboembolism in ambulatory cancer patients receiving chemotherapy

[Venous thromboembolism: risk factors and prophylaxis]

Venous thromboembolism is an important complication in tumour patients as it occurs frequently in these patients and causes relevant morbidity. The risk of thromboembolic complications in tumour patients is 3-9 times higher than in non-tumour patients and is the second most common cause of death in tumour patients. The risk of thrombosis depends on tumour-induced coagulopathy and on individual factors, type and stage of cancer, time since cancer diagnosis as well as type of systemic cancer therapy. Thromboprophylaxis in tumour patients is effective but can be associated with increased bleeding. Even though there are currently no dedicated recommendations for individual tumour entities, international guidelines recommend prophylactic measures in high-risk patients. A thrombosis risk of >8-10% can be considered an indication for thromboprophylaxis, which is indicated by a Khorana score ≥2, and should be calculated individually using nomograms. In particular, patients with a low risk of bleeding should receive thromboprophylaxis. Risk factors and symptoms of a thromboembolic event should also be intensively discussed with the patient and materials for patient information should be handed out.

Ambulatory cancer patients: who should definitely receive antithrombotic prophylaxis and who should never receive

Up to 15-20% of cancer patients experience one or more episodes of venous thromboembolism during cancer disease. Approximately 80% of all cancer-associated venous thromboembolic events occur in non-hospitalized patients. Routine thromboprophylaxis for outpatients with cancer who start new anticancer treatment is currently not recommended by the international guidelines due to the high heterogeneity of these patients in terms of VTE or bleeding risks, the difficulties in selecting patients at high risk, and the uncertainty of duration of prophylaxis. Although the international guidelines endorsed the Khorana score for estimating the thrombotic risk in ambulatory cancer patients, the discriminatory performance of this score is not completely convincing and varies according to the cancer type. Consequently, a minority of ambulatory patients with cancer receive an accurate screening for primary prophylaxis of VTE. The aim of this review is to provide support to physicians in identifying those ambulatory patients with cancer for whom thromboprophylaxis should be prescribed and those that should not be candidate to thromboprophylaxis. In absence of high bleeding risk, primary thromboprophylaxis should be recommended in patients with pancreatic cancer and, probably, in patients with lung cancer harboring ALK/ROS1 translocations. Patients with upper gastrointestinal cancers are at high risk of VTE, but a careful assessment of bleeding risk should be made before deciding on antithrombotic prophylaxis. Primary prevention of VTE is not recommended in cancer patients at increased risk of bleeding as patients with brain cancer, with moderate-to-severe thrombocytopenia or severe renal impairment.

Anticoagulation for the Prevention of Arterial Thrombosis in Ambulatory Cancer Patients: Systematic Review and Meta-Analysis

Background

The risk of arterial thrombotic events (ATEs) is high among patients on systemic anticancer therapies. Despite the efficacy of anticoagulants in the prevention of cancer-associated venous thromboembolism, it is unknown whether anticoagulation is effective to prevent ATEs.

Objectives

This study sought to examine the efficacy and safety of anticoagulants in ATE prevention among ambulatory cancer patients.

Methods

We performed a systematic review using Medline, Embase, Scopus, and Cochrane Central Register of Controlled Trials (CENTRAL) from inception to May 21, 2022, and included studies comparing oral or parenteral anticoagulation with no anticoagulation among ambulatory patients receiving systemic anticancer therapy with no other indication for anticoagulation. The primary outcome was ATE (myocardial infarction, ischemic stroke, intra-abdominal arterial embolism, or peripheral artery occlusion). The secondary outcomes were major and nonmajor bleeding and all-cause mortality.

Results

Fourteen randomized trials involving low-molecular-weight heparins, direct oral anticoagulants, and warfarin were included. ATEs were captured as coefficacy endpoints or adverse events. Anticoagulant use was not associated with a reduction in ATEs compared with placebo or standard treatment (RR: 0.73, 95% CI: 0.50-1.04; P = 0.08; I2 = 0%). RRs of major and minor bleeding were 1.56 (95% CI: 1.12-2.17) and 2.25 (95% CI: 1.45-3.48) with anticoagulant use. In 13 trials that reported all-cause mortality, risk of death was not reduced with anticoagulants (RR: 0.99; 95% CI: 0.95-1.02; P = 0.38; I2 = 0%).

Conclusions

Anticoagulants did not reduce ATE risk among ambulatory patients on systemic anticancer therapy and were associated with increased bleeding. Based on the current data, anticoagulants have a limited role in ATE prevention in this population as a whole.

Prevention of venous thromboembolism in patients with cancer

Venous thromboembolism (VTE) is a major cause of both morbidity and mortality in patients with cancer. Venous thromboembolism, which includes both deep vein thrombosis and pulmonary embolism, affects a sizable portion of patients with malignancy and can have potentially life threatening complications. Accurate assessment of risk as well as diagnosis and treatment of this process is paramount to preventing death in this high risk population. Various risk models predictive of venous thromboembolism in patients with cancer have been developed, and knowledge of these rubrics is essential for the treating oncologist. Subgroups of particular interest are inpatients receiving chemotherapy, postoperative patients after surgical debulking, and patients undergoing radiotherapy. Numerous newer drugs have become available for the prevention of venous thromboembolism in patients with cancer who are at high risk of developing the disease. These include the class of drugs called direct oral anticoagulants, (DOACs) which do not require the same monitoring that other modalities have previously required and are taken by mouth, preventing the discomfort associated with subcutaneous strategies. The appropriate risk stratification and intervention to prevent venous thromboembolism are vital to the treatment of patients with cancer.

Cost-effectiveness of apixaban and rivaroxaban in thromboprophylaxis of cancer patients treated with chemotherapy in Spain

BACKGROUND

Apixaban and rivaroxaban are two direct-acting oral anticoagulants (DOACs) recommended for thromboprophylaxis in cancer patients treated with chemotherapy in an ambulatory setting. We aimed to assess the cost-utility of thromboprophylaxis with apixaban and rivaroxaban vs no thromboprophylaxis in ambulatory cancer patients starting chemotherapy with an intermediate-to-high risk of venous thromboembolism (VTE), Khorana score ≥ 2 points.

METHODS

A cost-effectiveness analysis was performed from the perspective of Spain's National Health System (NHS) using an analytical decision model in the short-term (180 days) and a Markov model in the long-term (5 years). Transition probabilities were obtained from randomized, double-blind, placebo-controlled clinical trials of apixaban and rivaroxaban in adult ambulatory patients with cancer at risk for VTE, treated with chemotherapy (AVERT and CASSINI trials). The costs (€2,021) were taken from Spanish sources. The utilities of the model were obtained through the EQ-5D questionnaire. Deterministic (base case) and probabilistic (second-order Monte Carlo simulation) analyses were conducted.

RESULTS

In the probabilistic sensitivity analysis, apixaban generated a cost per patient of €1,082 ± 187, with a 95% confidence interval (CI) of €713-1,442, while no prophylaxis produced a cost per patient of €1,146 ± 218, with a 95% CI of €700-1,491, with a saving of €64 per patient and a gain of 0.008 QALYs. Likewise, rivaroxaban provided a cost per patient of €993 ± 133, with a 95% CI of €748-1,310, while no prophylaxis produced a cost per patient of €872 ± 152, with a 95% CI of €602-1,250, with an additional expense of €121 per patient and a gain of 0.008 QALYs.

CONCLUSIONS

In thromboprophylaxis of cancer patients, the use of apixaban and rivaroxaban generated similar costs compared to non-prophylaxis, without the difference found being statistically significant, with a clinically insignificant QALY gain.

2022 international clinical practice guidelines for the treatment and prophylaxis of venous thromboembolism in patients with cancer, including patients with COVID-19

The International Initiative on Thrombosis and Cancer is an independent academic working group of experts aimed at establishing global consensus for the treatment and prophylaxis of cancer-associated thrombosis. The 2013, 2016, and 2019 International Initiative on Thrombosis and Cancer clinical practice guidelines have been made available through a free, web-based mobile phone application. The 2022 clinical practice guidelines, which are based on a literature review up to Jan 1, 2022, include guidance for patients with cancer and with COVID-19. Key recommendations (grade 1A or 1B) include: (1) low-molecular-weight heparins (LMWHs) for the initial (first 10 days) treatment and maintenance treatment of cancer-associated thrombosis; (2) direct oral anticoagulants for the initial treatment and maintenance treatment of cancer-associated thrombosis in patients who are not at high risk of gastrointestinal or genitourinary bleeding, in the absence of strong drug-drug interactions or of gastrointestinal absorption impairment; (3) LMWHs or direct oral anticoagulants for a minimum of 6 months to treat cancer-associated thrombosis; (4) extended prophylaxis (4 weeks) with LMWHs to prevent postoperative venous thromboembolism after major abdominopelvic surgery in patients not at high risk of bleeding; and (5) primary prophylaxis of venous thromboembolism with LMWHs or direct oral anticoagulants (rivaroxaban or apixaban) in ambulatory patients with locally advanced or metastatic pancreatic cancer who are treated with anticancer therapy and have a low risk of bleeding.

Thrombotic events in patients using cyclin dependent kinase 4/6 inhibitors, analysis of existing ambulatory risk assessment models and the potential influences of tumor specific risk factors

Cyclin dependent kinase 4 of 6 inhibitors (CDKi) are key therapeutics in the treatment of advanced breast cancer and have recently been approved in small cell lung cancer for the prevention of myelosuppression. Thrombotic events have emerged as a significant treatment related adverse event in up to 5% of patients in clinical trials and has been reported at higher rates, up to 10%, in real world analysis. The prothrombotic mechanisms of CDKis, however, remain unknown. Cancer specific risk assessment models exist to identify who may be at highest risk of thrombosis and who could potentially benefit from prophylactic anticoagulation. However, these models may not be accurate in patients taking CDKis and may not fully capture recently identified thrombotic risk factors such as tumor specific somatic mutations. In the following manuscript, we summarize the literature on thrombotic events with CDKis in clinical trials and real-world settings, review the existing thrombosis risk assessment models for ambulatory cancer patients, and discuss the literature on tumor mutations and role in cancer associated thrombosis.