Primary Thromboprophylaxis in Ambulatory Cancer Patients: Where Do We Stand?

Cancer-associated venous thromboembolism: a comprehensive review

It has been 200 years since the first case of cancer-associated thrombosis (CAT) was reported. Venous thromboembolism (VTE) remains a leading cause of morbidity and mortality in cancer patients. Malignant tumors interact with the coagulation system in complex ways. CAT continues to pose a significant challenge in clinical practice. The risk factors for CAT are complex and multifactorial, primarily including patient, cancer, and therapy-related factors. We have introduced assessment models for CAT and bleeding risk, but the performance of these models has been less than satisfactory. Currently, the main anticoagulant drugs for treating CAT include vitamin K antagonists (VKAs), low molecular weight heparin (LMWH), and direct oral anticoagulants (DOACs). We have provided a detailed overview of the advantages and disadvantages of these three types of drugs and suggestions on choosing the appropriate type of medication for different clinical scenarios. CAT incidence, pathophysiology, risk factors, risk prediction models, and recent advancements in treatment and management are summarized in this review.

Tumor gene expression is associated with venous thromboembolism in patients with ductal pancreatic adenocarcinoma

INTRODUCTION

In patients with pancreatic cancer, the risk of venous thromboembolism (VTE) is high compared to other cancer types, suggesting that tumor-intrinsic features drive hypercoagulability. Tumor gene expression analysis may help unravel the pathogenesis of VTE in these patients and help to identify high-risk patients.

AIM

To evaluate the association between tumor gene expression patterns and VTE in patients with pancreatic cancer.

METHODS

In this retrospective cohort study RNA-sequence data from surgically resected tumor material from patients with pancreatic ductal adenocarcinoma (PDAC) was used to identify genes associated with the presence of venous thromboembolism (i.e., pulmonary embolism or deep-vein thrombosis) within one year follow-up after surgery. Additionally, VTE risk and expression of coagulation related genes in two molecular subtypes of pancreatic cancer was assessed.

RESULTS

Out of 151 patients, 10 (6.6 %) developed deep-vein thrombosis or pulmonary embolism within one year follow-up. Differential expression analysis yielded 89 genes significantly differentially expressed in patients with VTE compared to those without VTE, including ATP6V0A4, SYT14 and ZNF114. The incidence of VTE in classical subtype was higher (n = 9; 7.6 %) than in basal-like subtype (n = 1;4 %), but this difference was not statistically significant (SHR 1.79; 95 % CI 0.22-14.3). Forty-two coagulation-associated genes were identified that were differentially expressed between these molecular subtypes, including F5, PLAU, SERPINE1, and C4BPB.

CONCLUSIONS

Patients with pancreatic cancer and VTE show a different tumor gene expression profile than those without VTE. Multiple coagulation-related genes were differentially expressed in classical versus basal-like molecular subtype, suggesting that there is a difference in pro-thrombotic phenotype.

Characterization of thrombosis risk in ambulatory patients with cancer: results of the observational, prospective, multicenter CARTAGO study

BACKGROUND

Venous thromboembolism (VTE) is one of the leading causes of death in patients with cancer. Currently, there is a need to develop an easily applicable risk model that can identify patients who will benefit from receiving primary thromboprophylaxis to reduce the incidence of VTE.

PATIENTS AND METHODS

This was a non-interventional, multicenter, observational, prospective study carried out in 62 Oncology and Hematology services in Spain and Portugal between January 2018 and December 2019. The main objective of the CARTAGO study was to develop a predictive model within a competitive risk framework to assess the risk of VTE in patients with cancer undergoing chemotherapy, biological, or hormonal treatment.

RESULTS

A total of 1596 patients were analyzed. VTE events occurred in 124 (8%) during the 6-month follow-up period (42% of deep vein thrombosis [DVT], 48% of pulmonary embolism [PE], and 10% of both DVT and PE). Four variables were selected for the multivariate predictive model to determine the risk of VTE (tumor type, D-dimer, compression of a vessel by the tumor, and leukocyte count). The 4 variables were associated with an increased risk of VTE (C-statistic, 0.646 [95%CI, 0.620-0.673]). The most significant variables in the internal validation with bootstrapping were the "very high risk" tumors (hazard ratio [HR] 2.032; 95%CI, 1.287-3.211).

CONCLUSION

The CARTAGO model predicts the VTE risk in patients with cancer receiving anticancer therapy in an outpatient setting. This model can easily aid in identifying ambulatory patients who would probably benefit from primary thromboprophylaxis.

The Role of Anticoagulation on Venous Thromboembolism Primary Prophylaxis in Low- to Intermediate-Risk Ambulatory Cancer Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

The role of anticoagulants in the primary prevention of venous Thromboembolism(VTE) in high-risk cancer patients has been proven in previous studies; however, the routine use of thromboprophylaxis in cancer patients with Khorana score≤ 2 is still debated. This systematic review and meta-analysis aimed to investigate the role of prophylaxis with anticoagulants in cancer patients with low to moderate risk for first time.

METHODS

PubMed, Scopus, Google Scholar, and Web of Science databases were searched with Mesh terms to find Randomized controlled trial studies (RCTs) that evaluated the effect of thromboprophylaxis against placebo on VTE up to January 2024 in low-risk cancer patients. This systematic review was conducted based on the PRISMA guidelines. Heterogeneity between studies was evaluated using the I2 test. Egger's test was used to check publication bias. In general, 21 studies with 9985 participants were included.

RESULTS

The majority of studies had high quality and low risk of bias. The pooled estimate showed that using anticoagulants compared to placebo significantly reduces the risk of VTE (HR: 0.53, 95% CI: 0.43, 0.60, I2: 8.1%). Analysis of subgroups based on the class of anticoagulants showed that both direct oral anticoagulants (DOACs) (HR: 0.46, 95% CI: 0.36, 0.56, I2:8.5%) and Low molecular weight heparin (LMWH) (HR: 0.60, 95% CI: 0.51, 70, I2:0%) were significantly related to VTE risk compared to placebo. A pooled estimate of 18 studies did not show a significant association between increased major bleeding and anticoagulant prophylaxis. (HR: 1.25, 95% CI: 0.96, 1.54, I2: 4%).

CONCLUSION

Anticoagulant prophylaxis with both classes of LMWHs and DOACs compared to placebo can be associated with a reduction in VTE risk in low-to-intermediate risk cancer patients. DOACs were associated with a greater reduction in VTE risk. Anticoagulant prophylaxis had no significant relationship with increased major bleeding.

A nomogram for predicting the risk of venous thromboembolism in patients with solid cancers

Cancer patients with venous thromboembolism (VTE) are prone to poor prognoses. Thus, we aimed to develop a nomogram to predict the risk of VTE in these patients. We retrospectively analyzed 791 patients diagnosed with solid tumors between January 2017 and May 2021 at Tongji Hospital. Univariate logistic analysis and multivariate logistic regression were adopted in this study. Our results indicated that age ≥ 60 years, tumor stages III-IV, platelet distribution width (PDW) ≤ 12.6%, albumin concentration ≤ 38.8 g/L, lactate dehydrogenase (LDH) concentration ≥ 198 U/L, D-dimer concentration ≥ 1.72 µg/mL, blood hemoglobin concentration ≤ 100 g/dL or the use of erythropoiesis-stimulating agents and cancer types were independent risk factors. The nomogram prediction model was developed based on the regression coefficients of these variables. We assessed the performance of the nomogram by calibration plot and the area under the receiver operating characteristic curve and compared it with the Khorana score. The concordance index (C- index) of the nomogram was 0.852 [95% confidence interval (CI) 0.823 to 0.880], while the Khorana score was 0.681 (95% CI 0.639 to 0.723). Given its performance, this nomogram could be used to select cancer patients at high risk for VTE and guide thromboprophylaxis treatment in clinical practice, provided it is validated in an external cohort.

Risk of venous thromboembolism and bleeding after major surgery for ovarian cancer: standard in-hospital versus extended duration of thromboprophylaxis

BACKGROUND

Venous thromboembolism (VTE) is a frequent complication in patients with ovarian cancer after major surgery. Based on limited data, international guidelines recommend extended thromboprophylaxis for up to 28 days.

OBJECTIVES

To assess the incidence of VTE and bleeding within 30 days following major surgery in patients with ovarian cancer and to evaluate the association between VTE and thromboprophylaxis duration.

METHODS

This was a single-center, retrospective, "before-after" cohort study in patients with ovarian cancer undergoing major surgery. Before July 2019, the local protocol mandated a standard course of thromboprophylaxis during hospital stay only. From July 2019 onward, patients received extended thromboprophylaxis for 28 days. The cumulative incidences of VTE and major bleeding within 30 days after surgery were estimated using the Kaplan-Meier method, with 95% confidence intervals (CIs). Cox regression analysis was performed to evaluate the association between thromboprophylaxis duration and VTE incidence.

RESULTS

Between January 2018 and December 2020, 250 women were included, of which 118 (47.2%) received extended and 132 (52.8%) standard thromboprophylaxis. During follow-up, 12 patients developed VTE (cumulative incidence, 4.8%; 95% CI, 2.1-7.4) and 2 major bleeding (cumulative incidence 0.8%; 95% CI, 0.0-1.9). Compared with standard thromboprophylaxis, VTE incidence was numerically lower with extended duration of thromboprophylaxis (5/118 [4.2%] vs 7/132 [5.3%]) but not significantly different (hazard ratio, 0.80; 95% CI, 0.25-2.52). The risk of major bleeding was similar in both groups (1/118 [0.8%] vs 1/132 [0.8%]; hazard ratio, 1.12; 95% CI, 0.07-17.89).

CONCLUSIONS

The cumulative VTE incidence in patients with ovarian cancer following major surgery was considerable. Extended thromboprophylaxis was safe and associated with a numerically lower risk of VTE but not significantly different.

[Prophylaxis and management of cancer-associated thrombosis: Practical issues about anticoagulant use]

Cancer-associated thrombosis (CAT) is a common complication resulting from various vascular mechanisms related to cancer, antitumoral therapy and patient status, and is associated with a poor prognosis. Anticoagulants recommended for CAT treatment or prevention mainly include low molecular weight heparin (LMWH) and direct oral anticoagulants (DOACs). Regarding thromboprophylaxis, a situation for which LMWH is a preferred option due to a lower risk of hemorrhage especially in patients with unresected gastro-intestinal and genito-urinary malignancies, the identification of patients at risk is a major issue. For patients with established CAT, the main issue is the choice of the most appropriate anticoagulant therapy. Because of the convenience of oral formulation, DOACs are an attractive option, and their efficacy has been shown in randomized trials. However, such studies are limited by selection biases, which make the analyzed population not representative of the real-life setting, as for instance cancers associated with a high risk of hemorrhage, or antitumoral therapies (e.g., tyrosine kinase inhibitors) known to interact with DOACs and then modifying their bioavailability. Caution associated with DOAC use is highlighted by most updated guidelines that recommend a case-by-case-based approach. The aim of the present paper is to help the oncologists make the most appropriate decision regarding the choice of anticoagulant therapy in a context of thromboprophylaxis or established CAT management in a patient with a solid tumor. The main issues are addressed through key practical questions, the answers of which are based on the current guidelines and additional published data or expert opinions.

The association between cancer diagnosis, care, and outcomes in 1 million patients hospitalized for acute pulmonary embolism

OBJECTIVES

To evaluate the clinical care provided to cancer patients hospitalized for acute pulmonary embolism (PE), as well as the association between type of cancer, in-hospital care, and clinical outcomes.

METHODS

This study examined the in-hospital care (systemic thrombolysis, catheter-directed thrombolysis, and surgical thrombectomy/embolectomy) and clinical outcomes (mortality, major bleeding, and hemorrhagic stroke) among adults hospitalized due to acute PE between October 2015 to December 2018 using the National Inpatient Sample (NIS). Multivariable logistic regression analysis was used to determine adjusted odds ratios (aOR) with 95% confidence interval (95% CI).

RESULTS

Of 1,090,130 hospital records included in the analysis, 216,825 (19.9%) had current cancer diagnoses, including lung (4.7%), hematological (2.5%), colorectal (1.6%), breast (1.3%), prostate (0.8%), and 'other' cancer (9.0%). Cancer patients had lower adjusted odds of receiving systemic thrombolysis, catheter-directed therapy, and surgical thrombectomy/embolectomy compared with their non-cancer counterparts (P < 0.001), except for systemic thrombolysis (aOR 0.96, 95% CI 0.85-1.09, P = 0.553) and catheter-directed therapy (aOR 0.82, 95% CI 0.67-1.00, P = 0.053) for prostate cancer. Cancer patients had greater odds of mortality (P < 0.05). Lung cancer patients had the highest odds of mortality (aOR 2.68, 95% CI 2.61-2.76, P < 0.001) and hemorrhagic stroke (aOR 1.75, 95% CI 1.61-1.90, P < 0.001), while colorectal cancer patients had the greatest odds of bleeding (aOR 2.04, 95% CI 1.94-2.15, P < 0.001).

CONCLUSION

Among those hospitalized for PE, cancer diagnoses were associated with lower odds of invasive management and poorer in-hospital outcomes, with metastatic status being an especially important determinant. Appropriateness of care could not be assessed in this study.

Primary thromboprophylaxis in not surgically treated intra-luminal gastrointestinal cancer (ILGC) treated with first-line chemotherapy: A single institution preliminary safety report

Occurrence of venous thromboembolism in cancer patients (patients) undergoing chemotherapy is a remarkable concern for the oncologist. In addition, careful attention has to be paid to the possible major bleeding when patients carrying gastrointestinal cancer need antithrombotic therapies. To date some Cancer Associated Thrombosis (CAT) risk scores as Khorana and PROTECHT score have been developed to identify the cancer population at high-risk for venous thromboembolism (VTE). Consensus guidelines recommend to consider also low molecular weight heparin (LMWH) for primary thromboprophylaxis in high-risk patients. This is a report on a retrospective case series of 15 intra-luminal not surgically treated gastrointestinal cancer patients deemed high risk for VTE. The patients had a Khorana or PROTECHT score of 2 points or more (at least ≥ 2 points). They were undergoing first line chemotherapy in the absence of endoscopic signs of cancer spontaneous bleeding. A prophylactic dose of LMWH was administered just before starting the chemotherapy session and until 48 hours after its completion. The authors mainly aimed to report occurrence of clinically perceptible gastrointestinal bleeding events. Fifteen patients were administered LMWH - median age: 59 (range: 42-79); gender: male 12 (80%); tumor type: stomach - 13 patients (86%); gastro-esophageal junction: 2 patients (14%). Duration of heparin treatment: the total treatment duration was 228 days; mean 15.2 days (range: 5-45); nadroparin: mean 14.7 days (range: 5-45); enoxaparin: mean 10.1 days (range: 5-20); parnaparin: a total of 5 days. None of the patients experienced perceptible gastrointestinal bleeding. Short-term LMWH thromboprophylaxis appeared to be safe for this series of patients.

GDF-15, hs-TnT and NT proBNP for Predicting Risk of Venous Thromboembolism in Ambulatory Cancer Patients Receiving Chemotherapy

Growth Differentiation Factor-15 (GDF-15), high-sensitivity cardiac Troponin T (hs-TnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are associated with increased risk of venous thromboembolism (VTE) in non-cancer patients. However, the performance of these biomarkers in cancer patients is unknown. Our objective was to assess performance of these biomarkers in predicting VTE in cancer patients at intermediate to high risk for VTE (Khorana Score≥2). We used 1-month plasma samples from AVERT trial patients to determine if GDF-15, NT-proBNP and hs-TnT levels are associated with VTE incidence between one- and 7-months from the start of chemotherapy. The minimal Euclidean distance of the Receiver Operating Characteristic curve was used to derive optimal cut-offs for GDF-15 and NT-proBNP given there was no evidence of a commonly used cut-off. Logistic and Fine and Gray competing risk regression analysis were used to calculate odds ratios (OR) and subdistribution hazard ratios (SHR), respectively, while adjusting for age, sex, anticoagulation and antiplatelet therapy. We tested in two groups: all patients (n=476, Model 1) and all patients with non-primary brain cancers (n=454, Model 2). In Model 1 and 2, GDF-15 ≥2290.9pg/mL had adjusted ORs for VTE of 1.65 (95%CI: 0.89-3.08), and 2.28 (95%CI: 1.28-4.09), respectively. hs-TnT ≥14.0pg/mL was associated with higher odds of VTE in Model 1 and 2 [adjusted ORs: 2.26 (95%CI: 1.40-3.65), 2.03 (95%CI: 1.07-3.84), respectively]. For NT-proBNP, levels ≥183.5pg/mL was not associated with VTE. Similar results were observed in the Fine and Gray analysis. Our results indicate that increased GDF-15 and hs-TnT levels predicted increased VTE risk.

Validation of the Khorana score for predicting venous thromboembolism in 40 218 cancer patients initiating chemotherapy

The Khorana score is recommended for guiding primary venous thromboembolism prophylaxis in cancer patients, but its clinical utility overall and across cancer types remains debatable. Also, some previous validation studies have ignored competing risk of death, hereby potentially overestimating venous thromboembolism risk. We identified ambulatory cancer patients initiating chemotherapy without other indications for anticoagulation using Danish health registries and estimated six-month cumulative incidence of venous thromboembolism stratified by Khorana levels. Analyses were conducted with and without considering death as competing risk using the Kaplan-Meier method versus the cumulative incidence function. Analyses were performed overall and stratified by cancer types. Of 40,218 patients, 35.4% were categorized by Khorana as low risk (score 0), 53.6% as intermediate risk (score 1-2) and 10.9% as high risk (score ≥3). Considering competing risk of death, the corresponding six-month risks of venous thromboembolism were 1.5% (95% CI 1.3-1-7), 2.8% (95% CI 2.6-3.1), and 4.1% (95% CI 3.5-4.7), respectively. Among patients recommended anticoagulation by guidelines (Khorana score ≥2), six-month risk was 3.6% (95% CI 3.3-3.9). Kaplan-Meier analysis overestimated incidence up to 23% compared with competing risk analyses. Using the guideline-recommended threshold of ≥2, the Khorana score did not risk stratify patients with hepatobiliary or pancreatic cancer, lung cancer, and gynecologic cancer. In conclusion, the Khorana score was able to stratify ambulatory cancer patients according to risk of venous thromboembolism, but not for all cancer types. Absolute risks varied by methodology but were lower than in key randomized trials. Thus, although certain limitations with outcome identification using administrative registries apply, the absolute benefit of implementing routine primary thromboprophylaxis in an unselected cancer population may be smaller than seen in randomized trials.

Incidence, timing and risk factors of venous thromboembolic events in patients with pancreatic cancer

INTRODUCTION

Pancreatic cancer is associated with a high risk of venous thromboembolism (VTE). However, comprehensive data on incidence, timing and relevant determinants of VTE in this particular population are scarce. Current study assesses incidence, timing and predictors of VTE in pancreatic cancer through different phases of disease.

METHODS

All pancreatic cancer patients treated in our tertiary referral center between 2013 through 2017 were studied. Occurrence of VTE was evaluated from diagnosis through end of follow-up or death. Relevant determinants of VTE were identified in logistic regression models. Hazard ratios were calculated to evaluate impact of VTE on overall survival.

RESULTS

In total, 361 patients were followed for a median period of 43 months; 64 were diagnosed with VTE (18%). Most were tumor related thrombosis (59%), incidental (75%) and occurred after anti-cancer treatment had been stopped (80%), only 1.6% occurred during remission phase. Stage IV pancreatic cancer was a predictor for VTE (hazard ratio (HR) 2.46, 95% confidence interval (CI) 0.9-6.8). Biliary drainage (HR 0.52, 95%CI 0.28-0.98) and tumor resection (HR 0.45, 95%CI 0.45-1.83) were protective factors. VTE was not associated with worse survival (HR 1.3; 95% CI 0.97-1.74).

CONCLUSIONS

VTE in pancreatic cancer is disease-stage dependent, with 80% occurring in advanced phases of disease when patients no longer receive active treatment. We speculate that this is the main reason for the absence of a survival effect of VTE in our cohort. These practice-based findings should be taken into account when considering wide-spread introduction of primary thromboprophylaxis in patients with pancreatic cancer.

Primary thromboprophylaxis in ambulatory cancer patients with a high Khorana score: a systematic review and meta-analysis

Guidelines suggest thromboprophylaxis for ambulatory cancer patients starting chemotherapy with an intermediate to high risk of venous thromboembolism (VTE) according to Khorana score. Data on thromboprophylaxis efficacy in different Khorana score risk groups remain ambiguous. We sought to evaluate thromboprophylaxis in patients with an intermediate- to high-risk (≥2 points) Khorana score and an intermediate-risk score (2 points) or high-risk score (≥3 points) separately. MEDLINE, Embase, and CENTRAL were searched for randomized controlled trials (RCTs) comparing thromboprophylaxis with placebo or standard care in ambulatory cancer patients. Outcomes were VTE, major bleeding, and all-cause mortality. Relative risks (RRs) were calculated in a profile-likelihood random-effects model. Six RCTs were identified, involving 4626 cancer patients. Thromboprophylaxis with direct oral anticoagulants (DOACs) or low molecular weight heparin (LMWH) significantly reduced VTE risk in intermediate- to high-risk (RR, 0.51; 95% confidence interval [CI], 0.34-0.67), intermediate-risk (RR, 0.58; 95% CI, 0.36-0.83), and high-risk patients (RR, 0.45; 95% CI, 0.28-0.67); the numbers needed to treat (NNTs) were 25 (intermediate to high risk), 34 (intermediate risk), and 17 (high risk), respectively. There was no significant difference in major bleeding (RR, 1.06; 95% CI, 0.69-1.67) or all-cause mortality (RR, 0.90; 95% CI, 0.82-1.01). The numbers needed to harm (NNHs) for major bleeding in intermediate- to high-risk, intermediate-risk, and high-risk patients were 1000, -500, and 334, respectively. The overall NNH was lower in DOAC studies (100) versus LMWH studies (-500). These findings indicate thromboprophylaxis effectively reduces the risk of VTE in patients with an intermediate- to high-risk Khorana score, although the NNT is twice as high for intermediate-risk patients compared with high-risk patients.

Pulmonary embolism at autopsy in cancer patients

BACKGROUND

Pulmonary embolism (PE) is a potentially fatal disease, but data on the incidence of fatal PE in cancer patients are scant.

OBJECTIVE

We sought to estimate the proportion of cancer patients with PE at autopsy.

METHODS

For this retrospective cohort study, all autopsy reports of cancer patients were retrieved from PALGA: Dutch Pathology Registry and used for data extraction. The primary outcome was PE at time of autopsy, defined as any clot obstructing a pulmonary artery. The secondary outcome was venous thromboembolism, defined as the composite of thrombotic PE, deep vein thrombosis, splanchnic vein thrombosis, or internal jugular vein thrombosis.

RESULTS

A total of 9571 cancer patients were included. In 1191 (12.4%; 95% confidence interval [CI], 11.8-13.1) patients, one or more PE events were observed at autopsy, of whom 1074 (90.2%) had a thrombotic embolism, 168 (14.1%) a tumor embolism, 9 (0.8%) a septic embolism, 7 (0.6%) a fat tissue embolism, and 3 (0.3%) a bone marrow embolism. Among patients with PE for whom the cause of death was specified in the autopsy report, death was considered PE-related in 642 patients (66.7%), which was 6.7% of the total study population. Venous thromboembolism was observed in 1223 (12.8%; 95% CI, 12.1-13.5) patients.

CONCLUSION

The proportion of PE in cancer patients at autopsy is substantial. Although the study population is not representative for the total cancer population, it suggests that PE is an important disease complication in cancer patients.

D-Dimer Enhances Risk-Targeted Thromboprophylaxis in Ambulatory Patients with Cancer

BACKGROUND

Thromboprophylaxis for ambulatory patients with cancer is effective, although uncertainties remain on who should be targeted. Using D-dimer values from individuals enrolled to the AVERT trial, we sought to identify and validate a more efficient venous thromboembolism (VTE) risk threshold for thromboprophylaxis.

MATERIALS AND METHODS

The AVERT trial compared thromboprophylaxis with apixaban with placebo among patients with cancer with a Khorana Risk Score ≥2. The D-dimer measured at randomization was used to calculate an individualized 6-month VTE risk using the validated CATScore. A modified intention-to-treat analysis was used to assess efficacy (VTE) and safety (major and overall bleeding) in the (a) complete cohort and (b) ≥8% and < 8% 6-month VTE risk thresholds.

RESULTS

Five hundred seventy-four patients were randomized in the AVERT trial; 466 (81%) with baseline D-dimer were included in the study. Two hundred thirty-seven subjects received apixaban; 229 received placebo. In the complete cohort, there were 13 (5.5%) VTE events in the apixaban arm compared with 26 (11.4%) events in the placebo arm (adjusted hazard ratio [aHR] 0.49 [0.25-0.95], p < .05). Number needed to treat (NNT) to prevent one VTE = 17. Eighty-two (35%) and 72 (31%) patients in the apixaban and placebo arms, respectively, had a 6-month VTE risk ≥8%. In this subgroup, 7 (8.4%) VTE events occurred with apixaban and 19 (26.3%) events with placebo (aHR 0.33 [0.14-0.81], p < .05), NNT = 6. Individuals with a VTE risk <8% derived no benefit from apixaban thromboprophylaxis (aHR 0.89 [0.30-2.65), p = .84). Increased rates of overall bleeding were observed with apixaban in both the complete (aHR 2.11 [1.09-4.09], p < .05) and ≥ 8% predicted risk cohorts (aHR 2.87 [0.91-9.13], p = .07).

CONCLUSION

A 6-month VTE risk threshold of ≥8% increases the efficiency of risk-targeted thromboprophylaxis in ambulatory patients with cancer.

IMPLICATIONS FOR PRACTICE

Ambulatory patients with cancer receiving chemotherapy have an increased risk of venous thromboembolism (VTE). A Khorana Risk Score (KRS) ≥2 is currently the suggested threshold for thromboprophylaxis. Using baseline D-dimer values from individuals enrolled to the AVERT trial, this retrospective validation study identifies a 6-month VTE risk of ≥8% as a more efficient threshold for thromboprophylaxis. At this threshold, the number needed to treat to prevent one VTE is 6, compared with 17 when using a KRS ≥2. Conversely, individuals with a predicted risk of <8% derive no clinical benefit from thromboprophylaxis. Future prospective studies should validate this threshold for outpatient thromboprophylaxis.

Venous Thromboembolism in Cancer Patients on Simultaneous and Palliative Care

Simultaneous care represents the ideal integration between early supportive and palliative care in cancer patients under active antineoplastic treatment. Cancer patients require a composite clinical, social and psychological management that can be effective only if care continuity from hospital to home is guaranteed and if such a care takes place early in the course of the disease, combining standard oncology care and palliative care. In these settings, venous thromboembolism (VTE) represents a difficult medical challenge, for the requirement of acute treatments and for the strong impact on anticancer therapies that might be delayed or, even, totally discontinued. Moreover, cancer patients not only display high rates of VTE occurrence/recurrence but are also more prone to bleeding and this forces clinicians to optimize treatment strategies, balancing between hemorrhages and thrombus formation. VTE prevention is, therefore, regarded as a double-edged sword. Indeed, while on one hand the appropriate use of antithrombotic agents can reduce VTE occurrence, on the other it significantly increases the bleeding risk, especially in the frail patients who present with multiple co-morbidities and poly-therapy that can interact with anticoagulant drugs. For these reasons, thromboprophylaxis should start while active cancer treatment is ongoing, according to a simultaneous care model in a patient-centered perspective.