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Patients with cancer have an increased risk of thrombosis requiring anticoagulants and/or antiplatelet agents, and they can also encounter thrombocytopenia due to cancer itself or cancer therapies. They often undergo many procedures such as tissue or bone marrow biopsies, placement of central access lines, diagnostic or therapeutic draining procedures, lumbar puncture, and more. Management of antithrombotic agents or thrombocytopenia around the time of these procedures is highly variable. In this document, the Hemostasis and Malignancy Subcommittee of the International Society on Thrombosis and Haemostasis aims to provide useful practice guidance in the management of antithrombotic agents and thrombocytopenia around the time of common procedures in patients with cancer.

Venous thromboembolism (VTE) is a common and impactful complication of cancer. Several clinical prediction rules have been devised to estimate the risk of a thrombotic event in this patient population, however they are associated with limitations. We aimed to develop a predictive model of cancer-associated VTE using machine learning as a means to better integrate all available data, improve prediction accuracy and allow applicability regardless of timing for systemic therapy administration. A retrospective cohort was used to fit and validate the models, consisting of adult patients who had next generation sequencing performed on their solid tumor for the years 2014 to 2019. A deep learning survival model limited to demographic, cancer-specific, laboratory and pharmacological predictors was selected based on results from training data for 23,800 individuals and was evaluated on an internal validation set including 5,951 individuals, yielding a time-dependent concordance index of 0.72 (95% CI = 0.70–0.74) for the first 6 months of observation. Adapted models also performed well overall compared to the Khorana Score (KS) in two external cohorts of individuals starting systemic therapy; in an external validation set of 1,250 patients, the C-index was 0.71 (95% CI = 0.65–0.77) for the deep learning model vs 0.66 (95% CI = 0.59–0.72) for the KS and in a smaller external cohort of 358 patients the C-index was 0.59 (95% CI = 0.50–0.69) for the deep learning model vs 0.56 (95% CI = 0.48–0.64) for the KS. The proportions of patients accurately reclassified by the deep learning model were 25% and 26% respectively. In this large cohort of patients with a broad range of solid malignancies and at different phases of systemic therapy, the use of deep learning resulted in improved accuracy for VTE incidence predictions. Additional studies are needed to further assess the validity of this model.

"The frequent concurrence of phlegmasia alba dolens with an appreciable cancerous tumor, led me to the inquiry whether a relationship of cause and effect did not exist between the two, and whether the phlegmasia was not the consequence of the cancerous cachexia." (translated from the original French). This famous quote, delivered in a lecture by Armand Trousseau in 1865, is widely recognized as the initial and insightful understanding of the relationship of thrombosis and cancer.Although the association of thrombosis with cancer has been recognized for over 150 years, only recently has there been meaningful advances in our understanding of the relationship. Contemporary translational research tools have greatly enhanced our understanding the unique aspects of the pathophysiology of the relationship; how cancer cells exploit multiple aspects of the coagulation system for primary and metastatic growth leading, leading to an increased thrombotic risk. Further, there has been a growing appreciation of the complexity of the treatment of cancer-associated thrombosis. The superiority of low molecular weight heparin over warfarin, published in 2003, represented the first important divergence from the approach to management of thrombosis in the non-cancer population. With the introduction of the new generation of anticoagulants, the direct oral anticoagulants, there has been continued evolution of management guidelines.This text presents a much needed and comprehensive update of the field of thrombosis and hemostasis in cancer. We are fortunate to have so many leading authorities contribute their expertise and insight into this work. In the following chapters, the reader will find insight and guidance that will enhance scholarship, as well as patient care.

Chemotherapy-induced thrombocytopenia (CIT) is a frequent complication of cancer therapy, leading to increased risk of bleeding, when the thrombocytopenia is severe (10,000/mcL). However, the major clinical relevance of CIT is the subsequent delay or dose reduction in chemotherapy. CIT, therefore, leads to reduced relative dose intensity (RDI) of cancer therapy. Reduced RDI has been shown in several studies to impact progression-free survival and other cancer outcomes. While there are a number of factors leading to reduced RDI, CIT is a common cause. We review the causes and clinical manifestations of CIT, the current recommendations for management, and the status of research to develop targeted therapies to treat CIT.

The management of cancer-associated thrombosis (CAT) is complex, and treatment strategies have been evolving over the past 15 years. It is well recognized that oral vitamin K antagonists are difficult to use in cancer patients, with higher rates of treatment failure and bleeding complications than in non-cancer patients. Low-molecular-weight-heparin (LMWH) became the widely accepted standard of care for treatment of cancer-associated thrombosis, following the CLOT study comparing dalteparin with warfarin in 2003. LMWH remains widely used for the treatment of CAT. However, in the past two years, several studies have served to validate direct oral anticoagulants as a safe and effective alternative to LMWH. Two randomized clinical trials comparing edoxaban and rivaroxaban with dalteparin, and several retrospective studies have shown the efficacy of edoxaban and rivaroxaban for the treatment of CAT. However, there is an evidence of increased bleeding with the DOACs, particularly gastrointestinal or urinary tract bleeding in patients with lesions within the gastrointestinal or urinary tracts. This chapter discusses the ongoing development of optimal treatment strategies for cancer-associated thrombosis.

Red blood cell (RBC) hydration is regulated in part by the Ca(2+) -activated K(+) efflux (Gardos) channel. Senicapoc selectively blocks potassium efflux through the Gardos channel, reducing RBC dehydration and haemolysis, and increasing haemoglobin levels in sickle cell disease (SCD). This randomized, placebo-controlled trial was designed to determine the safety and clinical efficacy of senicapoc in SCD patients. One hundred and forty-five patients were randomized to receive senicapoc and 144 patients to receive placebo for 52 weeks. Consistent with a previous study, patients in the senicapoc group had significantly increased haematocrit, haemoglobin, and decreased numbers of both dense erythrocytes and reticulocytes when compared to the placebo group. The unblinded Data Monitoring Committee terminated this study early due to a lack of efficacy when it determined that, despite improvements in anaemia and haemolysis, no significant improvement in the rate of sickle cell painful crises was observed in patients treated with senicapoc compared to those on placebo (0·38 vs. 0·31, respectively). Comparisons of the times to first, second and third crises between the senicapoc and placebo groups were not statistically significant. Nausea and urinary tract infections occurred more frequently in the senicapoc group than placebo. Serious adverse events were similar in the two groups.

Thrombosis is a major cause of morbidity and mortality in cancer patients. The pathogenesis of blood coagulation activation in oncological patients is complex and involves both clinical and biological factors. Abnormalities in one or more coagulation test are common in cancer patients, even without thrombotic manifestations, indicating an ongoing hypercoagulable condition. Moreover, venous thromboembolism (VTE) can be the first symptom of an occult malignancy in an otherwise healthy individual. The levels of laboratory markers of activation of blood coagulation parallel the development of malignancy, being the coagulant mechanisms important for both thrombogenesis and tumor progression. Besides general clinical risk factors for VTE, also disease-specific clinical factors, i.e., type and stage of the tumor, and anticancer therapies increase the thrombotic risk in these patients. Furthermore, biological factors, including the cancer cell-specific prothrombotic properties together with the host cell inflammatory response to the tumor, are relevant as well as unique players in the pathogenesis of the cancer-associated hypercoagulability. Cancer cells produce and release procoagulant and fibrinolytic proteins, inflammatory cytokines, and procoagulant microparticles. They also express adhesion molecules binding to the receptors of host vascular cells (i.e., endothelial cells, platelets, and leukocytes), thereby stimulating the prothrombotic properties of these normal cells, including the shed of cell-specific microparticles and neutrophil extracellular traps. Of interest, several genes responsible for the cellular neoplastic transformation drive the programs of hemostatic properties expressed by cancer tissues. A better understanding of such mechanisms will help the development of novel strategies to prevent and treat the Trousseau’s syndrome (i.e., cancer-associated thrombosis).