Sensitising mutations in lung adenocarcinomas causing malignant pleural effusion: impact on survival

<bold>Introduction & Background:</bold> A number of mutations in lung adenocarcinomas can allow treatment with targeted therapies, including EGFR, ALK, ROS-1 and BRAF mutations. However, the presence of sensitising mutations is not included in the two most commonly used prognostic scores for malignant pleural effusion (MPE) - the LENT and PROMISE scores. <bold>Aims & objectives:</bold> This study aimed to assess the impact of sensitising mutations in lung adenocarcinomas causing MPE on survival time. <bold>Methods:</bold> A cohort of patients diagnosed with MPE secondary to lung adenocarcinoma between 2015-2023 was generated from the Oxford University Hospitals pleural MDT database. The electronic medical records of these patients were reviewed to calculate the length of survival from MPE diagnosis, and to assess for the presence or absence of sensitising mutations. <bold>Results:</bold> 146 patients with MPE secondary to lung adenocarcinoma where molecular testing results were available were identified. Of these, 29 (19.9%) had a sensitising mutation, mostly commonly in the EGFR gene (n = 22). The median length of survival in those with a sensitising mutation was 403 days compared to 126 days in those without. Kaplan-Meier analysis using log-rank test demonstrated a significant difference between survival curves (p = 0.001) for the two groups. <bold>Conclusions:</bold> The presence of sensitising mutations in lung adenocarcinomas causing MPE significantly lengthens survival, and this should be considered when developing and using prognostic scores for patients with MPE.