Thromboembolic risk in lung cancer patients receiving systemic therapy

In this retrospective study, we investigated the influence of chemotherapy and immunotherapy on thromboembolic risk among US Veterans with lung cancer during their first six months of systemic therapy. Patients in the study cohort received treatment with common frontline agents that were divided into four groups: chemotherapy alone, immunotherapy alone, combination of chemo- and immunotherapies, and molecularly targeted therapies. The latter served as a control group of systemically treated lung cancer patients who received neither chemotherapy nor immunotherapy. The cohort experienced a 6.8% overall incidence of thromboembolic events with a median time to event of 49 days, but the analysis demonstrated significantly different rates among the different treatment groups. We explored models incorporating multiple confounding variables as well as the competing risk of death, and these results indicated that both chemotherapy and immunotherapy were associated with an increased incidence of thrombosis, either when given alone or combined, compared with the control group (6.91%, 9.09%, and 7.47% respectively versus 3.68%, p < 0.024). Both the Khorana score assessing thrombosis risk for cancer patients and the Charlson comorbidity score were found to be associated with increased risk of thrombosis in our analyses. Paradoxically, we found an association between risk of thrombosis and the use of prophylactic anticoagulation or aspirin during the first month of systemic treatment, accounting for several confounding variables including a patient's prior history of thrombosis. Additionally, our data suggest that thromboembolic events may occur more commonly in lung cancer patients treated with immunotherapy compared with chemotherapy. Further study is warranted to better determine the drivers of thromboembolic risk and to identify ways to mitigate this risk for patients.