Clinical Characteristic Outcomes and Mortality Among Cancer and Non-Cancer Patients Presented with Incidental Pulmonary Embolism

Introduction: Cancer patients are at risk of developing venous thromboembolism, which includes pulmonary embolism (PE) and deep vein thrombosis. Advances in multidetector computed tomography (CT) scanners have led to increased detection of PE. However, the natural course of incidental PE, particularly in cancer patients, remains controversial. The objectives of this study were to determine characteristics of PE and mortality among patients with and without cancer. Methods: This retrospective cohort study was conducted at a tertiary medical center in Thailand. Patients aged 15 or older who were diagnosed with PE between 2011 and 2020, identified by the International Classification of Diseases, 10th Revision codes, were included in this study. Electronic medical records were reviewed to confirm the diagnosis of PE, which was defined as radiological evidence of PE by CT with contrast or V/Q scan. Patients were classified into two groups: the incidental PE (iPE) group and the suspected PE (sPE) group. Incidental PE was defined as cases where patients underwent CT without a specific request to investigate PE. The primary outcome was 30-day mortality. Results: A total of 736 patients with acute PE were included in the study, with 281 classified as iPE and 455 as sPE. The mean age was 58.8 ± 14.3 years in the iPE group and 57.5 ± 16.2 years in the sPE group. Active cancer was more common in the iPE group compared to the sPE group (70.8% versus 46.6%, P<0.001). Patients in the sPE group were more likely to exhibit PE-related symptoms, including dyspnea (P<0.001), chest pain (P<0.001), tachycardia (P<0.001), tachypnea (P<0.001), shock (P<0.001), and oxygen saturation <90% (P<0.001). The sPESI score identified 84.9% of patients in the iPE group as high-risk and 94.0% in the sPE group. There was no significant difference in the risk of 30-day mortality between the iPE and sPE groups (odds ratio [OR] 0.73, 95% CI 0.52-1.04, P=0.08). However, subgroup analysis revealed that cancer patients with iPE had lower 30-day mortality compared to those in the sPE group (OR 0.40, 95% CI 0.26-0.61, P<0.001). There were no significant differences in 30-day mortality among non-cancer patients with iPE versus sPE (OR 1.31, 95% CI 0.66-2.59, P=0.44). Multivariable analysis showed that cancer patients with PE who had dyspnea (hazard ratio [HR] 1.92, 95% CI 1.13-3.37, P=0.016), tachycardia (HR 1.66, 95% CI 1.13-2.45, P=0.01), oxygen saturation <90% (HR 1.67, 95% CI 1.06-2.65), and ECOG performance status >1 (HR 1.98, 95% CI 1.22-3.21) were associated with a significantly increased risk of death. Conclusions: Although the overall mortality rate of patients with iPE was not significantly different from those with sPE, patients with active cancer had a higher risk of 30-day mortality, particularly if they exhibited symptoms related to PE.