A Predictive Risk Score for Cancer-Associated Thrombosis: Role of Screening In A Prospective Study

We evaluated the utility of screening for VTE using a previously developed clinical risk score (Khorana et al, Blood 2008) in a prospective cohort of cancer patients initiating outpatient chemotherapy but not receiving thromboprophylaxis.

Cancer patients initiating a new chemotherapy regimen and deemed high-risk based on a predictive risk model (score ≥3) were enrolled on an ongoing prospective cohort study with informed consent. Patients were evaluated with baseline and Q4 (± 1) week serial ultrasonography for upto 16 weeks; additionally, computed tomography scans for restaging were also evaluated for VTE.

Of 30 patients enrolled on study, 8 (27%) developed a VTE. This included 5 patients with DVT alone (17%), 1 patient with PE alone (3%) and 2 (7%) with both. Twenty-seven patients underwent a baseline ultrasound. Of these, 3 asymptomatic DVTs were identified (11%). Subsequent ultrasounds were performed in 18 patients at week 4 (0 DVT), 17 patients at week 8 (0 DVT) and 15 patients at week 12 (1 DVT, 7%). An additional two patients developed symptomatic DVT between weeks 1 and 4. Restaging CT scans identified an asymptomatic PE in 1 patient at week 6 and asymptomatic PE in 1 patient at week 9 with subsequent symptomatic DVT at week 10.

In a prospective observational study, 27% of cancer outpatients deemed high-risk using a clinical risk score developed VTE, a rate much higher than observed even in hospitalized acutely ill patients. Thus, this study confirms the validity of a previously described risk score. The role of thromboprophylaxis in this population is currently being tested. The value of screening ultrasonography should be considered in high-risk patients based on this risk score.

No relevant conflicts of interest to declare.