Haemoptysis risk in lung cancer associated thrombosis (L-CAT) patients who initiated anticoagulant therapy.

<bold>Introduction:</bold> Lung cancer is associated with an increased risk of cancer-associated thrombosis (<bold>L-CAT</bold>), which requires anticoagulation therapy. Anticoagulation therapy exposes patients to an increased bleeding risk. Haemoptysis is common in patients with lung cancer and may be severe. Little is known about the risk of haemoptysis in patients with L-CAT who initiated anticoagulation therapy. <bold>Method:</bold> We performed a retrospective observational study of lung cancer patients who initiated anticoagulant therapy for CAT, from January 1rst 2010, to December 31, 2022, in a tertiary university hospital. Primary aim was to determine the incidence of haemoptysis up-to 6 months of follow-up. Secondary aims were to assess risk factors for haemoptysis, its clinical impact, and its association on death at 6 months. <bold>Result:</bold> Among 108 patients with L-CAT, 9 patients (8.33%, 95% CI [3.12; 13.54]) presented a haemoptysis at 6 months. No event was fatal, but two patients required hospital admission, one of whom needed aerosol vasopressin therapy. History of bleeding was associated with the risk of haemoptysis (OR=16.88 95%CI [3.68; 77.30]). Relative risk of death at 6 months was 1.29, (95% [0.80; 2.07]) in patients with haemoptysis, compared to those who did not have haemoptysis. <bold>Conclusion:</bold> Haemoptysis occurred in about 8% of L-CAT patients after initiation of anticoagulant therapy. Most of the events were mild and had no impact on patient management. History of bleeding was the leading risk factor of haemoptysis. Prognostic impact of haemoptysis on patients’ survival deserve further research.