Objectives : The aim of ASTRIS, a real-world study, was to assess the safety and efficacy of osimertinib in patients with locally advanced or metastatic (stage IIIB-IV) epidermal growth factor receptor (EGFR) T790M mutation-positive non-small cell lung cancer (NSCLC) who had received prior EGFR-tyrosine kinase inhibitor (TKI) therapy. Here, we describe the Belgian subset of the global ASTRIS study. Methods : Patients received osimertinib orally as one 80 mg tablet once daily until disease progression or unacceptable toxicity. Socio-demographic data, medical history, disease progression and survival status were collected and molecular testing for EGFR status was performed. Safety was also assessed. All collected data were summarized using descriptive statistics. Results : Of the 31 Belgian patients enrolled in the study, 9 (29.0%) discontinued treatment for disease progression and 5 (16.1%) due to other reasons. Among the 31 patients treated with osimertinib, 16 (51.6%, 95% CI 33.1–69.8) had a clinical ...