189P Lung cancer in young adults, age < 45 years: Clinical characteristics, treatment, histological and molecular features

Lung Cancer occurrence in young adults before 45 years old is rare and remains poorly characterised, with inconsistant data from different studies. We conducted a retrospective study using computerised clinical records including young adult patients, aged 45 and under, diagnosed with lung cancer between 2010 and 2021. The study included patients with NSCLC (Non-Small Cell Lung Cancer) or SLC (Small Cell Lung Cancer) at three University Hospital Centers in Paris, France. The primary objective was to describe the clinical, histological, and molecular characteristics at the time of diagnosis. Comparative analyses, stratified by age, sex, and cannabis/tobacco smoking status, were performed in the NSCLC group at all stages, and in those with localized or metastatic tumour. Overall survival of patients with stage IV NSCLC was also evaluated. A total of 189 patients with a median age of 41 years (min-max 18-45) were included in the study. The cohort showed an overrepresentation of women (45%), non-smokers (24%), EGFR or ALK or ROS1 alterations (40 % of the metastatic group) and adenocarcinoma (73 %) compared to the overall lung cancer population. In the metastatic NSCLC group, up to 75% of active tobacco smokers had a history of cannabis use. Although patients had a favourable overall condition (PS 0-1 in stage IV NSCLC group : 87 %), they predominantly had advanced stage disease (stage IV : 48 %). Median overall survival for stage IV patients was poor, reflecting aggressive disease (13 months IC95% (10,4-38,5)). Molecular alterations involving EGFR, ALK, or ROS1 were a significant good prognostic factor identified by multivariate analysis (HR: 0,18 IC95% (0,07-0,51); p <0,05). Cannabis users had mostly negative PD-L1 expression and no molecular alteration. Lung cancer in young adults has distinct clinicopathological, molecular and survival characteristics. This cohort may be indicative of the wider population of interest. A prospective approach could be considered to identify specific prognostic factors or to determine the lasting impact of lung cancer from a physical, psychological, or socio-economic perspective in this particular patient group.