Pulmonary embolism (PE) and deep venous thrombosis (DVT) together, known as venous thromboembolism (VTE), is one of the most common and most serious complications of patients with malignant tumors. According to previous studies, oncologic malignancy is an independent risk factor of VTE [1]. VTE is the second cause of death in patients with malignant tumors and indicates poor short term and long term prognosis [2, 3].

In recent years, the incidence of PE detected in routine CT scan of patients with malignant tumors has been increasing [4, 5]. Incidental PE on routine chest CT in patients without the suspicion of PE is defined as unsuspected PE (UPE). Although there have been studies on the incidence and risk factors of UPE in patients with oncologic malignancy in the last decade, there is no reliable data of the epidemiology, clinical characteristics and prognosis of UPE [6, 7].

Abdominal visceral adipose tissue (AVA) functions not only as lipid-storing depot, but also as important endocrinal and immune moderator. Previous studies suggested that different patterns of abdominal fat distribution were characterized by different risk of metabolic diseases [8]. Recent studies indicated that AVA was correlated with various diseases including tumor, cardiovascular and metabolic diseases.

As obesity (BMI ≥ 35 kg/m²) has been reported as an independent risk factor of VTE in malignant oncologic patients [9],we assume that AVA might be an independent risk factor of UPE in patients with oncologic malignancy, which has not been reported in English literature.

Our study aimed to investigate the risk factors of UPE in patients with digestive tract malignant tumors, emphasizing on the impact of AVA - including total abdominal adipose tissue volume (TAV), subcutaneous adipose tissue volume (SAV), and visceral adipose tissue volume (VAV) - on the occurrence of UPE.