Subclinical pulmonary embolism in first-line/induction therapy of lung cancer - a remaining clinically relevant adverse event.

Introduction: Pulmonary embolism (PE) at initial diagnosis and during first-line systemic treatment is clinically relevant in patients with lung cancer. However, real-world incidence of subclinical PE is not well established. Methods: Retrospective single-center analysis of patients at least 18 years old with non-small-cell lung cancer (NSCLC) or small-cell lung cancer (SCLC) who received first-line/induction systemic therapy. All patients underwent contrast-enhanced computed tomography (CT) of the thorax with bolus tracking for PE detection. Treatment response was assessed by restaging at weeks 6 and 12 after treatment initiation. Results: A total of 373 patients treated between 2019 and 2022 were included (261 NSCLC, 112 SCLC; 179 women and 194 men; median age 66 years [range, 22 to 86]; median smoking history 40 Pack Years [range, 0-150]). There was a predominance of locally advanced and metastatic disease (IB-IIB, n = 22; IIIA-C, n = 123; IVA-B, n = 228). Adenocarcinoma was the predominant histology among NSCLC cases (LUAD, n = 146), followed by squamous cell carcinoma and other NSCLC subtypes combined (n = 115); 112 patients had SCLC.PE was detected in 61/373 patients, of whom 58 (95%) had subclinical PE. In NSCLC, body-mass-index (BMI) was independently associated with occurrence of PE (OR = 1.111, p = 0.005), while central tumor localization (OR 5.637, p = 0.028) and vascular infiltration (OR 7.683, p = 0.010) were significantly associated with PE in SCLC. All patients with PE received anticoagulants according to national and international guidelines and no PE-related deaths occurred. Conclusion: This single-center analysis demonstrates a high incidence of subclinical PE in newly diagnosed lung cancer patients and identifies clinical risk factors associated with PE development.