Competing events in patients with malignant disease who are at risk for recurrent venous thromboembolism

Using the Khorana risk score to predict venous thromboembolism and overall survival in a cohort of Hispanic patients with solid malignancies

Background

The Khorana risk score (KRS) for prognosis of venous thromboembolism (VTE) has been rarely explored in Hispanic populations.

Objective

To determine the value of the KRS for prediction of VTE and overall survival (OS) among Hispanic individuals with cancer.

Methods

We retrospectively evaluated all outpatients with newly diagnosed solid tumours receiving systemic chemotherapy in Hospital San Juan Dios, San José, Costa Rica, from January to December 2021. The 6-month cumulative VTE incidence according to the KRS categories was estimated using the Fine & Gray competing risk model. A Kaplan-Meier analysis was used to compare OS among KRS categories. The Cox regression analysis was performed to calculate the hazard ratio (HR) and its corresponding 95% confidence interval (CI). The receiver operating characteristic (ROC) analysis was performed to identify the optimal cutoff value to predict VTE during follow-up.

Results

A total of 708 patients were included in the analysis. After a median follow-up of 8.13 months, the cumulative incidence of VTE at 6 months was 1.56% (95% CI: 0.83%-6.82%), 4.83% (95% CI: 2.81%-7.66%) and 8.84% (95% CI: 4.30%-15.42%) for low-, intermediate- and high-risk Khorana score categories, respectively (Gray's p value: 0.0178). The optimal cutoff for the KRS to predict VTE was 2 (area under the ROC curve: 0.65; 95% CI: 0.55-0.756). The KRS was independently associated with overall mortality (HR: 1.83; 95% CI: 1.46-2.29; p < 0.001, for the comparison of 'high-risk' and 'low-risk' KRS).

Conclusions

The KRS is a valid tool to predict VTE and mortality in a cohort of Hispanic outpatients with newly diagnosed solid tumours.

An empirical comparison of time-to-event models to analyse a composite outcome in the presence of death as a competing risk

INTRODUCTION

Competing risks arise when subjects are exposed to multiple mutually exclusive failure events, and the occurrence of one failure hinders the occurrence of other failure events. In the presence of competing risks, it is important to use methods accounting for competing events because failure to account for these events might result in misleading inferences.

METHODS AND OBJECTIVE

Using data from a multisite retrospective observational longitudinal study done in Ethiopia, we performed sensitivity analyses using Fine-Gray model, Cause-specific Cox (Cox-CSH) model, Cause-specific Accelerated Failure Time (CS-AFT) model, accounting for death as a competing risk to determine baseline covariates that are associated with a composite of unfavourable retention in care outcomes in people living with Human Immune Virus who were on both Isoniazid preventive therapy (IPT) and antiretroviral therapy (ART). Non-cause specific (non-CSH) model that does not account for competing risk was also performed. The composite outcome comprises of loss to follow-up, stopped treatment and death. Age, World Health Organisation (WHO) stage, gender, and CD4 count were the considered baseline covariates.

RESULTS

We included 3578 patients in our analysis. WHO stage III-or-IV was significantly associated with the composite of unfavourable outcomes, Sub-hazard ratio (SHR) = 1.31, 95% confidence interval (CI):1.04-1.65 for the sub-distribution hazard model, hazard ratio [HR] = 1.31, 95% CI:1.05-1.65, for the Cox-CSH model, and HR = 0.81, 95% CI:0.69-0.96, for the CS-AFT model. Gender and WHO stage were found to be significantly associated with the composite of unfavourable outcomes, HR = 1.56, 95% CI:1.27-1.90, HR = 1.28, 95% CI: 1.06-1.55 for males and WHO stage III-or-IV, respectively for the non-CSH model.

CONCLUSIONS

Results show that WHO stage III-or-IV is significantly associated with unfavourable outcomes. The results from competing risk models were consistent. However, results obtained from the non-CSH model were inconsistent with those obtained from competing risk analysis models.

Primary Thromboprophylaxis in Ambulatory Pancreatic Cancer Patients Receiving Chemotherapy: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Patients with pancreatic cancer (PC) carry the highest risk of venous thromboembolism (VTE) amongst all cancer patients. Appropriate use of primary thromboprophylaxis might significantly and safely reduce its burden. We performed a systematic review of published studies and meeting abstracts using MEDLINE and EMBASE through July 2020 to evaluate the efficacy and safety of primary thromboprophylaxis in ambulatory PC patients receiving chemotherapy. The Mantel–Haenszel random effect model was used to estimate the pooled event-based risk ratio (RR) and the pooled absolute risk difference (RD) with a 95% confidence interval (CI). Five randomized controlled studies with 1003 PC patients were included in this meta-analysis. Compared to placebo, thromboprophylaxis significantly decreased the risk of VTE (pooled RR 0.31, 95% CI 0.19–0.51, p < 0.00001, I² = 8%; absolute RD −0.08, 95% CI −0.12–−0.05, p < 0.00001, I² = 0%), with an estimated number needed to treat of 11.9 patients to prevent one VTE event. Similar reductions of VTE were observed in studies with parenteral (RR 0.30, 95% CI 0.17–0.53) versus oral anticoagulants (RR 0.37, 95% CI 0.14–0.99) and in studies using prophylactic doses of anticoagulants (RR 0.34, 95% CI 0.17–0.70) versus supra-prophylactic doses of anticoagulants (RR 0.27, 95% CI 0.08–0.90). The pooled RR for major bleeding was 1.08 (95% CI 0.47–2.52, p = 0.85, I² = 0%) and the absolute RD was 0.00 (95% CI −0.02–0.03, p = 0.85, I² = 0%). Evidence supports a net clinical benefit of thromboprophylaxis in ambulatory PC patients receiving chemotherapy. Adequately powered randomized phase III studies assessing the most effective anticoagulant and the optimal dose, schedule and duration of thromboprophylaxis to be used are warranted.

Epidemiology of Venous Thromboembolism After Second Cancer

Background

Venous thromboembolism (VTE) is a serious, yet preventable, complication in cancer. Some patients are diagnosed with a second cancer; however, little is known about the epidemiology of VTE in this population.

Methods

From Danish national healthcare registries, we studied all patients diagnosed with a first breast, prostate, lung, or colorectal cancer from 1995 to 2015. We estimated incidence rates (IRs) of VTE according to the timing of the diagnosis of a second cancer. We controlled for confounder variables in Poisson regression models.

Results

In total, 309,077 patients with a first breast, prostate, lung, or colorectal cancer were included in the study. A second cancer was diagnosed in 20,090 (6.5%) of these patients. In total, 11,908 VTEs were observed in the study period, 786 of these occurred after a diagnosis of second cancer. Second cancer types such as pancreas and stomach cancer were associated with fivefold higher IRs of VTE compared with second cancer types such as breast and prostate cancer. The IR of VTE was highest within the first 6 months after the second cancer was diagnosed (IR 40.5 per 1000 person-years, 95% CI 36.3–42.2) with no differences based on how long since the first cancer it was diagnosed.

Conclusion

The epidemiology of VTE after a second cancer is similar to the epidemiology of VTE after a first cancer with higher rates within the first months after aggressive second cancer types.

Primary Thromboprophylaxis in Pancreatic Cancer Patients: Why Clinical Practice Guidelines Should Be Implemented

Exocrine pancreatic ductal adenocarcinoma, simply referred to as pancreatic cancer (PC) has the worst prognosis of any malignancy. Despite recent advances in the use of adjuvant chemotherapy in PC, the prognosis remains poor, with fewer than 8% of patients being alive at 5 years after diagnosis. The prevalence of PC has steadily increased over the past decades, and it is projected to become the second-leading cause of cancer-related death by 2030. In this context, optimizing and integrating supportive care is important to improve quality of life and survival. Venous thromboembolism (VTE) is a common but preventable complication in PC patients. VTE occurs in one out of five PC patients and is associated with significantly reduced progression-free survival and overall survival. The appropriate use of primary thromboprophylaxis can drastically and safely reduce the rates of VTE in PC patients as shown from subgroup analysis of non-PC targeted placebo-controlled randomized trials of cancer patients and from two dedicated controlled randomized trials in locally advanced PC patients receiving chemotherapy. Therefore, primary thromboprophylaxis with a Grade 1B evidence level is recommended in locally advanced PC patients receiving chemotherapy by the International Initiative on Cancer and Thrombosis clinical practice guidelines since 2013. However, its use and potential significant clinical benefit continues to be underrecognized worldwide. This narrative review aims to summarize the main recent advances in the field including on the use of individualized risk assessment models to stratify the risk of VTE in each patient with individual available treatment options.

Low-molecular-weight-heparin versus a coumarin for the prevention of recurrent venous thromboembolism in high- and low-risk patients with active cancer: a post hoc analysis of the CLOT Study

In patients with active cancer and acute venous thromboembolism (VTE), the low-molecular-weight-heparin (LMWH) dalteparin is more effective than vitamin K antagonist (VKA) in reducing the risk of recurrent venous thromboembolism (rVTE) without increasing the risk of bleeding. However, the relative benefit of LMWH versus VKA in patients with active cancer at high or low risk of rVTE and bleeding is unclear. This post hoc analysis used data from the CLOT study to explore the efficacy and safety of LMWH versus VKA in preventing recurrent thrombosis in high- and low-risk patients with active cancer. High-risk patients were defined by metastatic disease and/or antineoplastic treatment at baseline; low-risk patients presented with neither. Among high-risk patients, rVTE occurred in 25/318 (8%) (LMWH) versus 53/314 (17%) (VKA) (hazard ratio, 0.44; p = 0.001). No significant difference was detected in the rate of major or any bleeding. The 6-month mortality rate was 40% (LMWH) versus 41% (VKA). In low-risk patients, 2/20 (10%) (LMWH) had rVTE versus 0/24 (0%) (VKA) (hazard ratio, not estimable; p = 0.998). No significant difference was detected in the rate of major or any bleeding. The 6-month mortality rate was 20% (LMWH) versus 29% (VKA). In patients with cancer-associated thrombosis at high risk of rVTE and bleeding, the LMWH dalteparin was more effective than VKA in reducing the risk of rVTE without increasing the risk of bleeding. No difference in rate of rVTE or bleeding was observed between LMWH and VKA among low-risk patients.

The Role of Direct Oral Anticoagulants in Treatment of Cancer-Associated Thrombosis

Venous thromboembolism (VTE) complicates the clinical course of approximately 5–10% of all cancer patients. Anticoagulation of the cancer patient often presents unique challenges as these patients have both a higher risk of recurrent VTE and a higher risk of bleeding than patients without cancer. Although low molecular weight heparins (LMWH) are the standard of care for the management of cancer-associated VTE, their use requires once or twice daily subcutaneous injections, which can be a significant burden for many cancer patients who often require a long duration of anticoagulation. The direct oral anticoagulants (DOACs) are attractive options for patients with malignancy. DOACs offer immediate onset of action and short half-lives, properties similar to LMWH, but the oral route of administration is a significant advantage. Given the higher risks of recurrent VTE and bleeding, there has been concern about the efficacy and safety of DOACs in this patient population. Data are now emerging for the use of DOACs in the cancer patient population from dedicated clinical trials. While recently published data suggest that DOACs hold promise for the treatment of cancer associated VTE, additional studies are needed to establish DOACs as the standard-of-care treatment. Many such studies are currently underway. The available data for the use of DOACs in the treatment of cancer-associated VTE will be reviewed, focusing on efficacy, safety, and other considerations relevant to the cancer patient.

Vitamin K Antagonists After 6 Months of Low-Molecular-Weight Heparin in Cancer Patients with Venous Thromboembolism

BACKGROUND

Low-molecular-weight heparin (LMWH) is the treatment of choice in cancer patients with venous thromboembolism. However, data on continuing LMWH treatment beyond 6 months remain scanty.

METHODS

We used the RIETE (Registro Informatizado Enfermedad TromboEmbólica) registry to compare the rate of venous thromboembolism recurrences and major bleeding appearing beyond the first 6 months of anticoagulant therapy in cancer patients with venous thromboembolism, according to therapy with LMWH or vitamin K antagonists (VKA). We performed a propensity score-matched cohort study.

RESULTS

After propensity matching, 482 cancer patients continued to receive LMWH and 482 switched to VKA. During the course of anticoagulant therapy (mean 275.5 days), 57 patients developed venous thrombosis recurrences (recurrent pulmonary embolism 26, recurrent deep vein thrombosis 29, both 2), 28 had major bleeding, 38 had nonmajor bleeding, and 129 died. No patient died of recurrent venous thrombosis, and 5 patients died of bleeding (2 were on LMWH, 3 on VKA). Patients who continued with LMWH had a similar rate of deep vein thrombosis recurrences (relative risk [RR] 1.41; 95% confidence interval [CI], 0.68-2.93), pulmonary embolism recurrences (RR 0.73; 95% CI, 0.34-1.58), major bleeding (RR 0.96; 95% CI, 0.51-1.79), or nonmajor bleeding (RR 1.15; 95% CI, 0.55-2.40), compared with those who switched to VKA, but a higher mortality rate (RR 1.58; 95% CI, 1.13-2.20).

CONCLUSIONS

In cancer patients with venous thromboembolism who completed 6 months of LMWH therapy, switching to VKA was associated with a similar risk of venous thrombosis recurrences or bleeding when compared with patients who continued LMWH.

Risk Factors, Biomarkers, Etiology, Outcome and Prognosis of Ischemic Stroke in Cancer Patients

Introduction: Cerebrovascular disease is the second most common complication in individuals with tumours. The aim of this study was to investigate risk factors, biomarkers, etiology and prognosis of ischemic stroke in cancer patients (ISCPs). Methods: The medical records of 619 consecutive patients who were admitted with acute ischemic stroke from January 2012 to November 2014 were retrospectively evaluated. The patients were divided into two groups (group 1, patients with an active cancer prior to the onset of ischemic stroke; group 2, patients without an active cancer history). The demographic data, risk factors, NIHSS scores, thrombocyte count, D-dimer, fibrinogen and C reactive protein (CRP) level at admission, modified Rankin Scale (mRS) scores in the follow-up period and location of lesions on DWI were recorded. The Mann-Whitney U test, chi-squared test and logistic regression was used for analyzing data, p<0.05 being considered statistically significant. Results: A total of 46 (7.4%) ISCPs were included. Hyperlipidemia was significantly lower in the ISCP group (p=0.001). Elevated thrombocyte counts, D-dimer, fibrinogen and CRP levels at admission, acute multiple ischemic lesions, other causes, mortality in hospital and worse outcome were significantly related to ISCP (p<0.05). On logistic regression analysis, follow up mRS>3, acute multiple ischemic lesions located in more than one vascular territory (AMIMCT) and other causes were significantly associated with ISCP (p<0.001). Conclusion: In our study, other causes, AMIMCT and mRS>3 were more common in the ISCP group. We consider that CCS could be more suitable for detecting other causes than TOAST. Biomarkers could be important in the ISCP group.

When can we stop anticoagulation in patients with cancer-associated thrombosis?

The optimal duration of anticoagulant therapy in patients with cancer-associated venous thromboembolism (VTE) is unknown. Without well-designed studies evaluating the efficacy, safety, and cost-effectiveness of continuing anticoagulant therapy beyond the acute treatment period of 3 to 6 months, evidence-based recommendations are lacking. Consensus guidelines generally suggest continuing anticoagulation treatment in patients with active cancer or receiving cancer treatment, with periodic reassessment of the risks and benefits. Unfortunately, with very little published data on the epidemiology of cancer-associated VTE beyond the initial 6 months, it is not possible for clinicians and patients to weigh risks and benefits in a quantitatively informed manner. Further research is needed to provide reliable and contemporary estimates on the risk of recurrent VTE off anticoagulant therapy, risk of bleeding on anticoagulant therapy, case fatality or all-cause mortality, and other important consequences of living with cancer-associated VTE. This chapter provides an overview of the published literature on real-world data on anticoagulant therapy use, the risks and risk factors of recurrent VTE and bleeding, and patient preference and values regarding long-term anticoagulation treatment. It will conclude with a pragmatic, experience-informed approach for tailoring anticoagulant therapy in patients with cancer-associated VTE.

When can we stop anticoagulation in patients with cancer-associated thrombosis?

The optimal duration of anticoagulation in patients with cancer-associated venous thromboembolism (VTE) is unknown. Without well-designed studies evaluating the efficacy, safety and cost-effectiveness of continuing anticoagulant therapy beyond the acute treatment period of 3 to 6 months, evidence-based recommendations are lacking. Consensus guidelines generally suggest continuing anticoagulation in patients with active cancer or receiving cancer treatment, with periodic reassessment of the risks and benefits. Unfortunately, with very little published data on the epidemiology of cancer-associated VTE beyond the initial 6 months, it is not possible for clinicians and patients to weigh risks and benefits in a quantitatively informed manner. Further research is needed to provide reliable and contemporary estimates on the risk of recurrent VTE off anticoagulation, risk of bleeding on anticoagulation, case fatality or all-cause mortality, and other important consequences of living with cancer-associated VTE. This chapter provides an overview of the published literature on real-world data on anticoagulant therapy use, the risks and risk factors of recurrent VTE and bleeding, and patient preference and values regarding long-term anticoagulation. It will conclude with a pragmatic, experience-informed approach for tailoring anticoagulant therapy in patients with cancer-associated VTE.

Risk of Arterial Thromboembolism in Patients With Cancer

BACKGROUND

The risk of arterial thromboembolism in patients with cancer is incompletely understood.

OBJECTIVES

The authors aimed to better define this epidemiological relationship, including the effects of cancer stage.

METHODS

Using the Surveillance Epidemiology and End Results-Medicare linked database, the authors identified patients with a new primary diagnosis of breast, lung, prostate, colorectal, bladder, pancreatic, or gastric cancer or non-Hodgkin lymphoma from 2002 to 2011. They were individually matched by demographics and comorbidities to a Medicare enrollee without cancer, and each pair was followed through 2012. Validated diagnosis codes were used to identify arterial thromboembolism, defined as myocardial infarction or ischemic stroke. Cumulative incidence rates were calculated using competing risk survival statistics. Cox hazards analysis was used to compare rates between groups at discrete time points.

RESULTS

The authors identified 279,719 pairs of patients with cancer and matched control patients. The 6-month cumulative incidence of arterial thromboembolism was 4.7% (95% confidence interval [CI]: 4.6% to 4.8%) in patients with cancer compared with 2.2% (95% CI: 2.1% to 2.2%) in control patients (hazard ratio [HR]: 2.2; 95% CI: 2.1 to 2.3). The 6-month cumulative incidence of myocardial infarction was 2.0% (95% CI: 1.9% to 2.0%) in patients with cancer compared with 0.7% (95% CI: 0.6% to 0.7%) in control patients (HR: 2.9; 95% CI: 2.8 to 3.1). The 6-month cumulative incidence of ischemic stroke was 3.0% (95% CI: 2.9% to 3.1%) in patients with cancer compared with 1.6% (95% CI: 1.6% to 1.7%) in control patients (HR: 1.9; 95% CI: 1.8 to 2.0). Excess risk varied by cancer type (greatest for lung), correlated with cancer stage, and generally had resolved by 1 year.

CONCLUSIONS

Patients with incident cancer face a substantially increased short-term risk of arterial thromboembolism.

Low-molecular weight heparin versus vitamin K antagonists for the treatment of cancer-associated thrombosis: A cost-effectiveness analysis

INTRODUCTION

Cancer-associated venous thromboembolism (VTE) is primarily treated with low-molecular weight heparin (LMWH), a strategy based on studies showing it to be superior to the vitamin K antagonist (VKA) warfarin for preventing VTE recurrence. Subsequent analyses suggest that the magnitude of this benefit might be less than previously determined. Neither patient-focused measures of utility nor the costs of each strategy have been evaluated in the current treatment era.

METHODS

This is a cost-effectiveness analysis of VKA and LMWH for the treatment of cancer-associated thrombosis through use of a microsimulation model of outcomes for competing anticoagulation management strategies from a 2014 United States societal perspective.

RESULTS

LMWH therapy added 0.27 QALYs relative to VKA treatment with an ICER of $217,007. One-way sensitivity analysis evaluating the utility of LMWH revealed that VKA was always the preferred strategy at a willingness to pay (WTP) threshold of $100,000 per QALY. Limitations include that the model incorporates a low VKA time in therapeutic range (TTR) and that the TTR in some centers may be higher thereby increasing the cost-effectiveness of the VKA strategy. Utilities for anticoagulation strategies were not derived from cancer patients, and preference is known to vary depending on how anticoagulation method is integrated with cancer treatment.

CONCLUSIONS

Our findings suggest that compared to LMWH, warfarin is a more cost-effective strategy to treat cancer-associated VTE. Although LMWH is associated with a modest increase in life expectancy, this increase comes at significant cost.

Competing Risk Analysis for Evaluation of Dalteparin Versus Unfractionated Heparin for Venous Thromboembolism in Medical-Surgical Critically Ill Patients

Failure to recognize the presence of competing risk or to account for it may result in misleading conclusions. We aimed to perform a competing risk analysis to assess the efficacy of the low molecular weight heparin dalteparin versus unfractionated heparin (UFH) in venous thromboembolism (VTE) in medical-surgical critically ill patients, taking death as a competing risk.This was a secondary analysis of a prospective randomized study of the Prophylaxis for Thromboembolism in Critical Care Trial (PROTECT) database. A total of 3746 medical-surgical critically ill patients from 67 intensive care units (ICUs) in 6 countries receiving either subcutaneous UFH 5000 IU twice daily (n = 1873) or dalteparin 5000 IU once daily plus once-daily placebo (n = 1873) were included for analysis.A total of 205 incident proximal leg deep vein thromboses (PLDVT) were reported during follow-up, among which 96 were in the dalteparin group and 109 were in the UFH group. No significant treatment effect of dalteparin on PLDVT compared with UFH was observed in either the competing risk analysis or standard survival analysis (also known as cause-specific analysis) using multivariable models adjusted for APACHE II score, history of VTE, need for vasopressors, and end-stage renal disease: sub-hazard ratio (SHR) = 0.92, 95% confidence interval (CI): 0.70-1.21, P-value = 0.56 for the competing risk analysis; hazard ratio (HR) = 0.92, 95% CI: 0.68-1.23, P-value = 0.57 for cause-specific analysis. Dalteparin was associated with a significant reduction in risk of pulmonary embolism (PE): SHR = 0.54, 95% CI: 0.31-0.94, P-value = 0.02 for the competing risk analysis; HR = 0.51, 95% CI: 0.30-0.88, P-value = 0.01 for the cause-specific analysis. Two additional sensitivity analyses using the treatment variable as a time-dependent covariate and using as-treated and per-protocol approaches demonstrated similar findings.This competing risk analysis yields no significant treatment effect on PLDVT but a superior effect of dalteparin on PE compared with UFH in medical-surgical critically ill patients. The findings from the competing risk method are in accordance with results from the cause-specific analysis.clinicaltrials.gov Identifier: NCT00182143.

Tinzaparin vs Warfarin for Treatment of Acute Venous Thromboembolism in Patients With Active Cancer: A Randomized Clinical Trial

IMPORTANCE

Low-molecular-weight heparin is recommended over warfarin for the treatment of acute venous thromboembolism (VTE) in patients with active cancer largely based on results of a single, large trial.

OBJECTIVE

To study the efficacy and safety of tinzaparin vs warfarin for treatment of acute, symptomatic VTE in patients with active cancer.

DESIGN, SETTINGS, AND PARTICIPANTS

A randomized, open-label study with blinded central adjudication of study outcomes enrolled patients in 164 centers in Asia, Africa, Europe, and North, Central, and South America between August 2010 and November 2013. Adult patients with active cancer (defined as histologic diagnosis of cancer and receiving anticancer therapy or diagnosed with, or received such therapy, within the previous 6 months) and objectively documented proximal deep vein thrombosis (DVT) or pulmonary embolism, with a life expectancy greater than 6 months and without contraindications for anticoagulation, were followed up for 180 days and for 30 days after the last study medication dose for collection of safety data.

INTERVENTIONS

Tinzaparin (175 IU/kg) once daily for 6 months vs conventional therapy with tinzaparin (175 IU/kg) once daily for 5 to 10 days followed by warfarin at a dose adjusted to maintain the international normalized ratio within the therapeutic range (2.0-3.0) for 6 months.

MAIN OUTCOMES AND MEASURES

Primary efficacy outcome was a composite of centrally adjudicated recurrent DVT, fatal or nonfatal pulmonary embolism, and incidental VTE. Safety outcomes included major bleeding, clinically relevant nonmajor bleeding, and overall mortality.

RESULTS

Nine hundred patients were randomized and included in intention-to-treat efficacy and safety analyses. Recurrent VTE occurred in 31 of 449 patients treated with tinzaparin and 45 of 451 patients treated with warfarin (6-month cumulative incidence, 7.2% for tinzaparin vs 10.5% for warfarin; hazard ratio [HR], 0.65 [95% CI, 0.41-1.03]; P = .07). There were no differences in major bleeding (12 patients for tinzaparin vs 11 patients for warfarin; HR, 0.89 [95% CI, 0.40-1.99]; P = .77) or overall mortality (150 patients for tinzaparin vs 138 patients for warfarin; HR, 1.08 [95% CI, 0.85-1.36]; P = .54). A significant reduction in clinically relevant nonmajor bleeding was observed with tinzaparin (49 of 449 patients for tinzaparin vs 69 of 451 patients for warfarin; HR, 0.58 [95% CI, 0.40-0.84]; P = .004).

CONCLUSIONS AND RELEVANCE

Among patients with active cancer and acute symptomatic VTE, the use of full-dose tinzaparin (175 IU/kg) daily compared with warfarin for 6 months did not significantly reduce the composite measure of recurrent VTE and was not associated with reductions in overall mortality or major bleeding, but was associated with a lower rate of clinically relevant nonmajor bleeding. Further studies are needed to assess whether the efficacy outcomes would be different in patients at higher risk of recurrent VTE.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01130025.

Recurrence of Venous Thromboembolism in Patients With Cancer Treated With Warfarin

Venous thromboembolism (VTE) is a common complication in patients with cancer. Previous randomized studies have demonstrated that the rates of recurrent VTE are lower in patients treated with low-molecular-weight heparin compared to warfarin. We performed a retrospective analysis of 236 patients with cancer managed by a dedicated oncology anticoagulation management service to compare "real-world" rates of recurrent VTE and bleeding in patients treated with warfarin versus parenteral anticoagulants. Initial anticoagulant regimen included a parenteral agent with transition to warfarin in 132 (55.9%) patients, enoxaparin in 53 (22.5%), dalteparin in 37 (15.7%), and fondaparinux in 14 (5.9%). Taking into account the competing risk of death, cumulative incidence of VTE recurrence at 6 months was 4.0% with warfarin, 10.3% with enoxaparin, 3.0% with dalteparin, and 7.7% with fondaparinux (P = .004). Bleeding complications occurred in 10.6% of patients on warfarin, 17.0% on enoxaparin, 27.0% on dalteparin, and 14.3% on fondaparinux (P = .089). In a dedicated anticoagulation clinic, specific for patients with cancer, warfarin may be an acceptable treatment for first thrombotic events in patients with cancer.

Estimating risk of venous thromboembolism in patients with cancer in the presence of competing mortality

BACKGROUND

In studies on cancer-associated venous thromboembolism (VTE), patients not only are at risk for VTE but also may die from their underlying malignancy.

OBJECTIVES

In this competing-risk (CR) scenario, we systematically compared the performance of standard (Kaplan-Meier estimator [1-KM]), log-rank test, and Cox model) and specific CR methods for time-to-VTE analysis.

PATIENTS AND METHODS

Cancer patients (1542) were prospectively followed for a median of 24 months. VTE occurred in 112 (7.3%) patients, and 572 (37.1%) patients died.

RESULTS

In comparison with the CR method, 1-KM slightly overestimated the cumulative incidence of VTE (cumulative VTE incidence at 12 and 24 months [1-KM vs. CR]: 7.22% vs. 6.74%, and 8.40% vs. 7.54%, respectively). Greater bias was revealed in tumor entities with high early mortality (e.g., pancreatic cancer, n = 99, 24-month cumulative VTE incidence: 28.37% vs. 19.30%). Comparing the (subdistribution) hazard of VTE between patients with low and high baseline D-dimer, the Cox model yielded a higher estimate than the corresponding CR model (hazard vs. subdistribution hazard ratio [95% CI] 2.85 [1.92-4.21] vs. 2.47 [1.67-3.65]). For this comparison, the log-rank test yielded a higher test statistic and smaller P-value than Gray's test (χ(2) on 1 degree of freedom: 29.88 vs. 21.34).

CONCLUSION

In patients with cancer who are at risk for VTE and death, standard and CR methods for time-to-VTE analysis can generate differing results. For 1-KM, the magnitude of bias is a direct function of competing mortality. Consequently, bias tends to be negligible in cancer patient populations with low mortality but can be considerable in populations at high risk of death.

Cancer-associated unsuspected pulmonary embolism

Clinically unsuspected pulmonary embolism (UPE) is frequently diagnosed in cancer patients undergoing routine computed tomography scans for staging purposes or treatment response evaluation. The reported incidence of UPE ranges from 1% to 5% which probably represents an underestimation. A significant proportion of cancer patients with UPE actually do have pulmonary embolism (PE) related symptoms. However, these can erroneously be attributed to the cancer itself or to cancer therapy leading to a delayed or missed diagnosis. The incidence of UPE is likely to increase further with the improvements of imaging techniques. Radiologic features of UPE appear similar to symptomatic PE with nearly half of the UPE located in central pulmonary arteries and one third involving both lungs. UPE in cancer patients is not a benign condition with rates of recurrent venous thromboembolic events, bleeding and a mortality rate comparable to cancer patients with symptomatic PE. Current guidelines suggest that UPE should receive similar initial and long-term anticoagulant treatment as for symptomatic PE. However, direct evidence regarding the treatment of UPE is scarce and treatment indications are largely derived from studies performed in cancer patients with symptomatic venous thromboembolism. Selected subgroups of cancer patients with UPE such as those with sub-segmental UPE may be treated conservatively by withholding anticoagulation and avoiding the associated bleeding risk, although this requires further evaluation.

Association between incident cancer and subsequent stroke

OBJECTIVE

A study was undertaken to examine the association between incident cancer and the subsequent risk of stroke.

METHODS

Using the Surveillance, Epidemiology, and End Results-Medicare linked database, we identified patients with a new primary diagnosis of breast, colorectal, lung, pancreatic, or prostate cancer from 2001 through 2007. These patients were individually matched by age, sex, race, registry, and medical comorbidities to a group of Medicare enrollees without cancer, and each pair was followed through 2009. Validated diagnosis codes were used to identify a primary outcome of stroke. Cumulative incidence rates were calculated using competing risk survival statistics.

RESULTS

Among 327,389 pairs of cancer patients and matched controls, the 3-month cumulative incidence of stroke was generally higher in patients with cancer. Cumulative incidence rates were 5.1% (95% confidence interval [CI] = 4.9-5.2%) in patients with lung cancer compared to 1.2% (95% CI = 1.2-1.3%) in controls (p < 0.001), 3.4% (95% CI = 3.1-3.6%) in patients with pancreatic cancer compared to 1.3% (95% CI = 1.1-1.5%) in controls (p < 0.001), 3.3% (95% CI = 3.2-3.4%) in patients with colorectal cancer compared to 1.3% (95% CI = 1.2-1.4%) in controls (p < 0.001), 1.5% (95% CI = 1.4-1.6%) in patients with breast cancer compared to 1.1% (95% CI = 1.0-1.2%) in controls (p < 0.001), and 1.2% (95% CI = 1.1-1.3%) in patients with prostate cancer compared to 1.1% (95% CI = 1.0-1.2%) in controls (p = 0.085). Excess risks attenuated over time and were generally no longer present beyond 1 year.

INTERPRETATION

Incident cancer is associated with an increased short-term risk of stroke. This risk appears highest with lung, pancreatic, and colorectal cancers.

How long is long enough? Extended anticoagulation for the treatment of cancer-associated deep vein thrombosis

A previously healthy 41-year-old man presents with left leg pain and shortness of breath. He has a 20–packyear history of smoking but quit 2 years ago. An ultrasound of the left leg shows thrombosis of the superficial femoral and popliteal veins.Onchest computed tomography (CT) angiogram, there is a large right hilar mass and enlarged mediastinal lymph nodes but no pulmonary emboli. He is treated with therapeutic doses of low–molecular weight heparin (LMWH), with brief interruptions for invasive procedures and surgery. Transbronchial biopsy is performed, and pathology yields a diagnosis of poorly differentiated non–small cell lung cancer (NSCLC; EGFR/KRAS wild type and ALK and ROS1 negative by fluorescent in situ hybridization). After additional tests, the patient is determined to have stage IIIA NSCLC. Subsequently, he receives concurrent chemotherapy consisting of cisplatin/etoposide and chest radiotherapy, resulting in a marked decrease in the size of the right hilar mass and mediastinal lymph nodes. He then undergoes right upper lobectomy and mediastinal lymph node dissection, which demonstrate no clinical or pathologic evidence of cancer. The patient returns to clinic, having been treated for >6 months with LMWH. He reports both mild shortness of breath with exertion and minimal chronic swelling of the left lower extremity. A follow-up ultrasound shows nonocclusive intraluminal thrombus in the left superficial femoral and popliteal veins; follow-up chest CT angiogram shows no evidence of pulmonary emboli.

Empirical comparison of methods for analyzing multiple time-to-event outcomes in a non-inferiority trial: a breast cancer study

BACKGROUND

Subjects with breast cancer enrolled in trials may experience multiple events such as local recurrence, distant recurrence or death. These events are not independent; the occurrence of one may increase the risk of another, or prevent another from occurring. The most commonly used Cox proportional hazards (Cox-PH) model ignores the relationships between events, resulting in a potential impact on the treatment effect and conclusions. The use of statistical methods to analyze multiple time-to-event events has mainly been focused on superiority trials. However, their application to non-inferiority trials is limited. We evaluate four statistical methods for multiple time-to-event endpoints in the context of a non-inferiority trial.

METHODS

Three methods for analyzing multiple events data, namely, i) the competing risks (CR) model, ii) the marginal model, and iii) the frailty model were compared with the Cox-PH model using data from a previously-reported non-inferiority trial comparing hypofractionated radiotherapy with conventional radiotherapy for the prevention of local recurrence in patients with early stage breast cancer who had undergone breast conserving surgery. These methods were also compared using two simulated examples, scenario A where the hazards for distant recurrence and death were higher in the control group, and scenario B. where the hazards of distant recurrence and death were higher in the experimental group. Both scenarios were designed to have a non-inferiority margin of 1.50.

RESULTS

In the breast cancer trial, the methods produced primary outcome results similar to those using the Cox-PH model: namely, a local recurrence hazard ratio (HR) of 0.95 and a 95% confidence interval (CI) of 0.62 to 1.46. In Scenario A, non-inferiority was observed with the Cox-PH model (HR = 1.04; CI of 0.80 to 1.35), but not with the CR model (HR = 1.37; CI of 1.06 to 1.79), and the average marginal and frailty model showed a positive effect of the experimental treatment. The results in Scenario A contrasted with Scenario B with non-inferiority being observed with the CR model (HR = 1.10; CI of 0.87 to 1.39), but not with the Cox-PH model (HR = 1.46; CI of 1.15 to 1.85), and the marginal and frailty model showed a negative effect of the experimental treatment.

CONCLUSION

When subjects are at risk for multiple events in non-inferiority trials, researchers need to consider using the CR, marginal and frailty models in addition to the Cox-PH model in order to provide additional information in describing the disease process and to assess the robustness of the results. In the presence of competing risks, the Cox-PH model is appropriate for investigating the biologic effect of treatment, whereas the CR models yields the actual effect of treatment in the study.