Arterial Thromboembolism Incidence in Japanese Patients With Lung Cancer

Patients with lung cancer tend to have a high incidence of arterial thromboembolism (ATE). However, although ATE is a life-threatening disease, there are insufficient studies evaluating patient characteristics associated with a high risk of ATE in patients with lung cancer. This study aimed to examine the incidence of ATE in Japanese patients with lung cancer and evaluate the incidence of ATE by histological types and treatment patterns to identify high-risk groups.

We conducted a retrospective cohort study using the National Health Insurance (NHI), Employees' Health Insurance (EHI), and Later-Stage Elderly Healthcare System (LSEHS) claims databases from April 1, 2014, to March 31, 2022. The patients were followed up for up to 5 years after lung cancer diagnosis. The cumulative incidence rates of ATE were calculated, and the histological subtype and treatment pattern were analyzed using the Cox proportional hazards model.

Among 6340 patients in EHI, 10,857 patients in NHI, and 13,039 patients in LSEHS, patient characteristics such as the median age and the prevalence of comorbidities were different among the three databases. The cumulative incidence rates at 1 year were 1.7%, 4.5%, and 7.2%, and those at 5 years were 3.5%, 8.0%, and 15.9%. The adjusted hazard ratio for small cell lung cancer compared to non-small cell lung cancer was 2.84 (95% confidence interval (CI): 1.46-5.54) in EHI, 0.93 (95% CI: 0.65-1.32) in NHI, and 1.11 (95% CI: 0.85-1.46) in LSEHS. The risk of ATE of RT + systemic therapy and systemic therapy only was higher than surgery only, with a statistically significant difference in the three databases.

In any database, the cumulative incidence of ATE increased over the 5 year observation period. Patients who received RT + systemic therapy and those who received systemic therapy only had a higher risk of ATE than those who underwent surgery only.