MA 07.03 Incidence, Predictors and Prognostic Significance of Thromboembolic Events in Patients with Advanced Alk-Rearranged NSCLCs

The incidence of venous thromboembolic events all along the course of the disease in advanced-stage lung adenocarcinomas is approximately 15 %. It is plausible that the different molecular subtypes might influence on the risk of thrombosis. Based on our clinical observation, and supported by limited data from isolated small series, patients bearing ALK rearranged tumors could be at a particularly high-risk of thromboembolic disease. We included consecutive patients diagnosed with advanced-stage ALK fusion positive non-small cell lung cancers (NSCLC) between January 2012 and December 2016. Clinical data were contributed by 29 Medical Centers from Spain and one large Academic Cancer Center from Portugal. Investigators at each institution retrospectively reviewed patients’ medical records. A thromboembolic event was defined as any venous or arterial thromboembolism, or both, at any site, documented by appropriate imaging studies, that occurred at the time or after advanced-stage cancer diagnosis. A total of 241 ALK-rearranged NSCLCs were included in our study. Half of the patients were never smokers (52 %), and most had stage IV pulmonary adenocarcinomas (n=204, 85%). Baseline brain and liver metastasis were detected in 22 % and 25 % of the patients respectively. Seventy-three patients (30 %) developed thromboembolic disease. In 54 patients (74 %) thromboembolic complications occurred within the first 6 months from diagnosis. In the multivariate competing-risk regression analysis, the presence of baseline liver metastases (HR of 1.85, CI 95 % 1.09-3.15; p = 0.021) and baseline leukocyte counts >11.0000 cells/mm3 (HR of 2.34, CI 95% 1.43-3.82; p = 0.001) were independent predictors of thromboembolic disease. Remarkably, 50 % of the patients with either liver metastases or leukocytosis at diagnosis developed thromboembolic disease. Patients experiencing thromboembolic events had shorter median overall survival (OS) (20 months) than patients without thrombosis (36 months) (p = 0.035). In the multivariate Cox Model, thromboembolic disease remained associated with worse OS (HR of 1.70, CI 95% 1.10-2.62; p = 0.016) when considered as a time-varying covariate. The presence of baseline thromboembolic disease (n = 24) was associated with a numerical non-significant increased risk of death (HR 1.67, CI 95 % 0.96-2.91; p = 0.068). Venous and/or arterial thromboembolic complications occur in a high proportion of patients with advanced-stage ALK fusion positive NSCLCs, particularly in the presence of baseline liver metastasis or leukocytosis. The development of thromboembolic disease is associated with a lower OS in these patients.