Identification and Characterization of Recurrent Venous Thrombosis In Cancer Patients

Venous thromboembolism (VTE) is a common cause of morbidity and mortality in cancer patients. Standard of care for treatment is Low Molecular Weight Heparin, but recurrence of VTE remains a concern. We performed a retrospective analysis of our institutional experience, to characterize the patients who had a recurrence of VTE while on therapeutic doses of Dalteparin.

1. To determine the VTE recurrence rate for cancer patients on therapeutic Dalteparin. 2. To elucidate potential risk factors for recurrence. 3. To determine the impact of recurrent VTE on overall survival.

Patients beginning treatment for VTE with dalteparin between 1/1/2008 and 12/10/ 2009 were retrospectively identified through the hospital's electronic medical records system and cases of recurrent VTE were characterized. Overall survival was estimated using the Kaplan-Meier method and the influence of VTE recurrence on overall survival was analyzed as a time-dependent covariate using a Cox proportional hazards model.

1,392 patients, treated for VTE with dalteparin were included in this study. 34 recurrent VTE episodes were identified. The overall incidence of recurrent thrombosis by six months was 2.3% (95% CI: 1.7%-3.3%). Older age was significantly associated with recurrence (p=0.04). Lung cancer patients had a significantly elevated risk of recurrence (5.6%, p=0.03). No other cancer types were associated with a significant trend to increased recurrent VTE rates. The incidence of recurrent VTE was higher among females compared to males (3.0% vs. 1.6%), although this trend was not statistically significant (P = 0.08). After adjusting for gender, sex and cancer diagnosis, developing a recurrent VTE was associated with a 3.0-fold hazard ratio of death (<0.0001).

The rate of recurrent VTE in cancer patients at MSKCC is low in comparison with previously published reports. However, we identified both older age and lung cancer diagnosis as statistically significant risk factors for recurrent VTE. Females also experienced a higher rate of recurrent thrombosis when compared to males, although this result was not statistically significant. The hazard ratio for death was three times that for a patient with recurrent thrombosis when compared to one without subsequent VTE, suggesting recurrence of VTE remains an important influence on cancer-associated mortality.

No relevant conflicts of interest to declare.