Background: Venous thromboembolism (VTE) is a common complication among patients with cancer. Patients with cancer and VTE are at a markedly increased risk for morbidity and mortality.Objective: These evidence-based guidelines of the American Society of Hematology (ASH) are intended to support patients, clinicians, and other health care professionals in their decisions about the prevention and treatment of VTE in patients with cancer.Methods: ASH formed a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The guideline development process was supported by updated or new systematic evidence reviews. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to assess evidence and make recommendations.Results: Recommendations address mechanical and pharmacological prophylaxis in hospitalized medical patients with cancer, those undergoing a surgical procedure, and ambulatory patients receiving cancer chemotherapy. The recommendations also address the use of anticoagulation for the initial, short-term, and long-term treatment of VTE in patients with cancer.Conclusions: Strong recommendations include not using thromboprophylaxis in ambulatory patients receiving cancer chemotherapy at low risk of VTE and to use low-molecular-weight heparin (LMWH) for initial treatment of VTE in patients with cancer. Conditional recommendations include using thromboprophylaxis in hospitalized medical patients with cancer, LMWH or fondaparinux for surgical patients with cancer, LMWH or direct oral anticoagulants (DOAC) in ambulatory patients with cancer receiving systemic therapy at high risk of VTE and LMWH or DOAC for initial treatment of VTE, DOAC for the short-term treatment of VTE, and LMWH or DOAC for the long-term treatment of VTE in patients with cancer.

Patients with active cancer have an increased risk of venous thromboembolism, which results in substantial morbidity, mortality, and health care expenditures. The Khorana score (range, 0 to 6, with higher scores indicating a higher risk of venous thromboembolism) has been validated to identify patients with cancer at elevated risk for this complication and may help select those who could benefit from thromboprophylaxis. We conducted a randomized, placebo-controlled, double-blind clinical trial assessing the efficacy and safety of apixaban (2.5 mg twice daily) for thromboprophylaxis in ambulatory patients with cancer who were at intermediate-to-high risk for venous thromboembolism (Khorana score, ≥2) and were initiating chemotherapy. The primary efficacy outcome was objectively documented venous thromboembolism over a follow-up period of 180 days. The main safety outcome was a major bleeding episode. Of the 574 patients who underwent randomization, 563 were included in the modified intention-to-treat analysis. Venous thromboembolism occurred in 12 of 288 patients (4.2%) in the apixaban group and in 28 of 275 patients (10.2%) in the placebo group (hazard ratio, 0.41; 95% confidence interval [CI], 0.26 to 0.65; P<0.001). In the modified intention-to-treat analysis, major bleeding occurred in 10 patients (3.5%) in the apixaban group and in 5 patients (1.8%) in the placebo group (hazard ratio, 2.00; 95% CI, 1.01 to 3.95; P=0.046). During the treatment period, major bleeding occurred in 6 patients (2.1%) in the apixaban group and in 3 patients (1.1%) in the placebo group (hazard ratio, 1.89; 95% CI, 0.39 to 9.24). Apixaban therapy resulted in a significantly lower rate of venous thromboembolism than did placebo among intermediate-to-high-risk ambulatory patients with cancer who were starting chemotherapy. The rate of major bleeding episodes was higher with apixaban than with placebo. (Funded by the Canadian Institutes of Health Research and Bristol-Myers Squibb–Pfizer Alliance; AVERT ClinicalTrials.gov number, NCT02048865.)

In patients with active cancer and venous thromboembolism, whether extended treatment with a reduced dose of an oral anticoagulant is effective in preventing recurrent thromboembolic events and decreasing bleeding is unclear. We conducted a randomized, double-blind, noninferiority trial with blinded central outcome adjudication. Consecutive patients with active cancer and proximal deep-vein thrombosis or pulmonary embolism who had completed at least 6 months of anticoagulant therapy were randomly assigned in a 1:1 ratio to receive oral apixaban at a reduced (2.5 mg) or full (5.0 mg) dose twice daily for 12 months. The primary outcome was centrally adjudicated fatal or nonfatal recurrent venous thromboembolism, assessed in a noninferiority analysis (margin of 2.00 for the upper boundary of the 95% confidence interval of the subhazard ratio). The key secondary outcome was clinically relevant bleeding, assessed in a superiority analysis. A total of 1766 patients underwent randomization at a median time since the index event of 8.0 months (interquartile range, 6.5 to 12.6); 866 patients were assigned to the reduced-dose group, and 900 to the full-dose group. The median treatment duration was 11.8 months (interquartile range, 8.3 to 12.1). Recurrent venous thromboembolism occurred in 18 patients (cumulative incidence, 2.1%) in the reduced-dose group and in 24 (cumulative incidence, 2.8%) in the full-dose group (adjusted subhazard ratio, 0.76; 95% confidence interval [CI], 0.41 to 1.41; P = 0.001 for noninferiority). Clinically relevant bleeding occurred in 102 patients (cumulative incidence, 12.1%) in the reduced-dose group and in 136 (cumulative incidence, 15.6%) in the full-dose group (adjusted subhazard ratio, 0.75; 95% CI, 0.58 to 0.97; P = 0.03). Mortality was 17.7% in the reduced-dose group and 19.6% in the full-dose group (adjusted hazard ratio, 0.96; 95% CI, 0.86 to 1.06). Extended anticoagulation with reduced-dose apixaban was noninferior to full-dose apixaban for the prevention of recurrent venous thromboembolism in patients with active cancer. The reduced dose led to a lower incidence of clinically relevant bleeding complications than the full dose. (Funded by the Bristol-Myers Squibb-Pfizer Alliance; API-CAT ClinicalTrials.gov number, NCT03692065.).

Direct oral anticoagulants (DOACs) are an emerging treatment option for patients with cancer and acute venous thromboembolism (VTE), but studies have reported inconsistent results. This systematic review and meta-analysis compared the efficacy and safety of DOACs and low-molecular-weight heparins (LMWHs) in these patients. MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, and conference proceedings were searched to identify relevant randomized controlled trials. Additional data were obtained from the original authors to homogenize definitions for all study outcomes. The primary efficacy and safety outcomes were recurrent VTE and major bleeding, respectively. Other outcomes included the composite of recurrent VTE and major bleeding, clinically relevant nonmajor bleeding (CRNMB), and all-cause mortality. Summary relative risks (RRs) were calculated in a random effects meta-analysis. In the primary analysis comprising 2607 patients, the risk of recurrent VTE was nonsignificantly lower with DOACs than with LMWHs (RR, 0.68; 95% CI, 0.39-1.17). Conversely, the risks of major bleeding (RR, 1.36; 95% CI, 0.55-3.35) and CRNMB (RR, 1.63; 95% CI, 0.73-3.64) were nonsignificantly higher. The risk of the composite of recurrent VTE or major bleeding was nonsignificantly lower with DOACs than with LMWHs (RR, 0.86; 95% CI, 0.60-1.23). Mortality was comparable in both groups (RR, 0.96; 95% CI, 0.68-1.36). Findings were consistent during the on-treatment period and in those with incidental VTE. In conclusion, DOACs are an effective treatment option for patients with cancer and acute VTE, although caution is needed in patients at high risk of bleeding.

Screening for cancer in patients with unprovoked venous thromboembolism (VTE) often is considered, but clinicians need precise data on cancer prevalence, risk factors, and the effect of different types of screening strategies. To estimate the prevalence of occult cancer in patients with unprovoked VTE, including in subgroups of different ages or those that have had different types of screening. MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials up to 19 January 2016. Prospective studies evaluating cancer screening strategies in adults with unprovoked VTE that began enrolling patients after 1 January 2000 and had at least 12 months of follow-up. 2 investigators independently reviewed abstracts and full-text articles and independently assessed risk of bias. 10 eligible studies were identified. Individual data were obtained for all 2316 patients. Mean age was 60 years; 58% of patients received extensive screening. The 12-month period prevalence of cancer after VTE diagnosis was 5.2% (95% CI, 4.1% to 6.5%). The point prevalence of cancer was higher in patients who had extensive screening than in those who had more limited screening initially (odds ratio [OR], 2.0 [CI, 1.2 to 3.4]) but not at 12 months (OR, 1.4 [CI, 0.89 to 2.1]). Cancer prevalence increased linearly with age and was 7-fold higher in patients aged 50 years or older than in younger patients (OR, 7.1 [CI, 3.1 to 16]). Variation in patient characteristics and extensive screening strategies; unavailability of long-term mortality data. Occult cancer is detected in 1 in 20 patients within a year of receiving a diagnosis of unprovoked VTE. Older age is associated with a higher cancer prevalence. Although an extensive screening strategy initially may detect more cancer cases than limited screening, whether this translates into improved patient outcomes remains unclear. None. (PROSPERO: CRD42016033371)