Radon Exposure in Colombian Never Smoker Patients with Non-Small Cell Lung Cancer: A Pilot Study.

e22521 Background: Lung cancer (LC) is the leading cause of cancer-related death globally, with 1.8 million deaths estimated in 2022. In Colombia, up to 74% of patients with LC are diagnosed with stage IV which negatively impacts survival, with 6,000 estimated deaths in 2022. The most critical strategy for reducing LC is the reduction of tobacco exposure; however, up to 38% of LC cases are not related to tobacco. Among other risk factors different from tobacco smoke; indoor radon, a radioactive gas found naturally in closed spaces, stands out and could be the most important one. In Latin America, information on the influence of radon on the incidence of LC is scarce. This study aims to establish the prevalence of Radon exposure in Colombian never-smoker LC patients. Methods: This is a Pilot study. Adult patients with de novo NSCLC diagnosis ( < 6 mo) were included. Past smokers (≥100 cigarettes in life or ≥1 cigarette daily for 6 mo) or patients with a change in place of living in the last 10 years were excluded. Sociodemographics, clinical, and molecular information were obtained and included in an eCRF using REDCap®, Radon measurement was done using a DTPA-type detector (Alfa-track). The detector was located in the patient's home, (60-140 cm from the floor at the point of least ventilation of the space to be measured), for 90 days, Subsequently an automated count quantification was carried out using the Radosys® system at a certified lab (Universidad Santiago de Compostella Radon Lab). The Radon levels were reported in Bq/m3, using the average value observed during the measurement period (The threshold was 20 Bq/m3). Results: Between February 2022 to May 2023, 30 patients were included in the study, 86.7% were women, 73% had stage IV disease at inclusion, 53% had a driver mutation, with EGFR being the most frequent (62,5%) followed by ALK (31.3%). The mean Radon levels were 25.6 Bq/m3 (5 – 48). No patient had Radon levels ≥100 Bq/m3. Conclusions: In this pilot study, we didn´t find high radon exposure among never-smoker NSCLC patients. 2 other studies on indoor Radon concentrations have been done in Colombia, with only one demonstrating high radon levels (≥100 Bq/m3) in Bogotá. These differences could be explained by the type of house, rainfall adjustment, or underlying rock composition in our study. It´s important to increase the sample size for a definitive conclusion and to explore other risk factors in non-smoker patients as the quality of air or occupation, among others. [Table: see text]