Venous thromboembolism in patients with cancer and factor XI deficiency.

Background: Factor XI (FXI) deficiency is associated with reduced venous thromboembolism (VTE) risk without increased spontaneous bleeding in the general population. FXI inhibitors show promise in preventing VTE in orthopedic surgery and are currently being investigated in cancer-associated VTE. However, there currently is no data regarding the potential efficacy of FXI inhibition for the management of hypercoagulability in cancer.

Objectives: To evaluate the incidence of VTE among patients with cancer and FXI deficiency compared to a matched control population.

Patients/methods: This is a retrospective study performed at Memorial Sloan Kettering Cancer Center (MSKCC) evaluating VTE incidence in patients with cancer and FXI deficiency (n=73) and matched controls with cancer and normal partial thromboplastin time (n=185). Index date was the date of first visit at MSKCC for cancer evaluation. Records were followed until VTE, death or last follow up, whichever occurred first. Patients from the two cohorts were matched for age, sex, surgery within 30 days from index date, primary cancer site and stage, platelet and hemoglobin levels at index.

Results: At 12 months, the cumulative incidence of VTE in the cohort with FXI deficiency was 4.1% (95% confidence interval [CI]: 1.1-11%) compared with 10.6% (95% CI: 6.6-16%, Gray test p=0.052) in the matched controls. Major surgery-related bleeding occurred in 12.9% of patients with FXI deficiency undergoing surgery from the index date through the end of follow-up, compared to 2.1% in the control cohort.

Conclusions: FXI deficiency appears to be associated with reduced VTE risk in individuals with cancer.