Continuation of Low-molecular-weight Heparin Treatment for Cancer-related Venous Thromboembolism: a Prospective Cohort Study in Daily Clinical Practice

Summary: Background Current guidelines recommend low-molecular-weight heparin (LMWH) monotherapy for 3-6 months as the first-line treatment for cancer-associated venous thromboembolism (VTE). However, although daily administration of LMWH injections over a course of several months may be burdensome, the number of patients who stop treatment because of LMWH side-effects is unknown. Objectives To evaluate the continuation rate and complications of daily LMWH injections in patients with cancer-associated VTE. Methods Consecutive patients with active cancer and objectively confirmed symptomatic proximal deep vein thrombosis and/or pulmonary embolism, treated at three Dutch hospitals and one Spanish hospital, were included to evaluate continuation LMWH therapy during LMWH treatment. Patients were excluded when they received other anticoagulants, were lost to follow-up, or experienced a venous catheter-associated thrombosis. Results A total of 372 patients were analyzed during LMWH treatment for a maximum of 180 days. The cumulative incidence of discontinuation was 21% (95% confidence interval [CI] 17-25) after a median period of 90 days (interquartile range 60-120 days). Only female sex was found to be significantly associated with premature LMWH discontinuation (odds ratio 1.6; 95% CI 1.03-2.5). Thirty patients (8.1%) developed recurrent VTE, 30 patients (8.3%) suffered a major bleed, and 106 patients (28%) died. Conclusion Our study reveals that one of five patients with cancer-associated VTE stopped LMWH injections because of side-effects. This finding provides relevant background information for current clinical trials investigating the efficacy and safety of direct oral anticoagulants as compared with LMWH.