Incidence and prognostic impact of venous thromboembolism in a prospective single-center cohort of patients with cancer: The THEO study.

Background

Venous thromboembolism (VTE) is a major complication in oncology, representing the second leading cause of death among cancer patients after tumor progression. Isolated superficial venous thrombosis (iSVT), historically considered benign, is now emerging as a potential marker of thromboembolic risk but remains underexplored in cancer populations.

Objective

To estimate the incidence of VTE and iSVT and evaluate the prognostic impact of VTE on all-cause mortality in a prospective cohort of patients with cancer.

Methods

This prospective single-center cohort study included 700 cancer patients at Centre Antoine Lacassagne (Nice, France), followed for 12 months with scheduled visits at 6 and 12 months. VTE (deep vein thrombosis [DVT] or pulmonary embolism [PE]) and iSVT occurring during prospective follow-up were identified and confirmed by imaging. Incidence rates per 1000 person-years and cumulative incidence functions (accounting for death as a competing risk) were calculated. The association between VTE occurring during follow-up and all-cause mortality was assessed using a Cox proportional hazards model with VTE modeled as a time-dependent covariate. The study was registered at ClinicalTrials.gov (NCT03826043).

Results

Of 700 enrolled patients, 516 were included in the analysis (median age: 65 years; 53.3% male). During 12 months of follow-up, 50 VTE events occurred (incidence: 147.5 per 1000 person-years), including DVT (110.2 per 1000) and PE (57.1 per 1000). The incidence of iSVT was 25.4 per 1000 person-years, substantially exceeding estimates reported for the general population. In multivariable time-dependent Cox regression adjusted for age, sex, and primary tumor site and stratified by baseline ECOG performance status, VTE was independently associated with an increased risk of all-cause mortality (adjusted HR 2.07, 95% CI 1.36-3.15, p < 0.001).

Conclusion

VTE and iSVT incidences in this dedicated cancer center were markedly higher than those reported in general and cancer populations. These findings underscore the need for tailored thromboprophylaxis and closer surveillance in oncology settings.