question: Introduction: COVID-19 pandemic has drastically changed the management of patients with cancer The prioritization of the healthcare towards COVID-19 patients could interfere with the initial diagnosis, resulting in delayed treatment and worse outcome We aimed to study the incidence of lung cancer new diagnosis, severity and clinical outcomes during Covid-19-period (during-COVID) compared to the same period in 2019 (before-COVID) Methods: Bicenter retrospective cohort study of newly diagnosed non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) patients before (Jan-Jun/19) and during COVID-19 (Jan-Jun/20) in Spain Clinical data were collected We primarily assessed the difference on new lung cancer cases between both periods, and the disease severity considering: Performance status (PS), stage and any significant complication at diagnosis Secondarily, we assessed the 30 days-mortality rate, progression-free survival (PFS) and overall survival (OS) by period Results: 162 newly diagnosed lung cancer patients (68% NSCLC and 32% SCLC) were enrolled, with median age of 66 years, 70% were male, 33% smokers, 25% with PS ≥2 Advanced disease was diagnosed in 50% of NSCLC and 61% SCLC;13% of NSCLC harbored driver alterations During-COVID, the number of new cases diagnosed decreased by 38% (43 NSCLC;19 SCLC), compared to before-COVID period (67 NSCLC;33 SCLC) More symptomatic cases were new diagnosed during vs before-COVID The Table 1 summarized clinical data and complications of new lung cancer cases by period and histology In NSCLC population diagnosed during-COVID, we observed more respiratory symptoms at diagnosis (30% vs 23% before-COVID) with mainly locally-advanced/advanced disease (82% vs 76% before-COVID) Among the cases hospitalized, the mortality during-hospitalization was 44% (2/9) vs 17% before-COVID In SCLC population diagnosed during-COVID, respiratory symptoms were more common (32% vs 24% before-COVID), but no more aggressive disease observed in terms of stage, complications and hospitalizations Among the 4 cases hospitalized at diagnosis, none died during-hospitalization vs 18% before-COVID (2/11) Overall, during-Covid the mOS was 6 7 months [95% CI, 5 4-not reached] vs 7 9 months [95% CI, 4 7-12] before-COVID In NSCLC, the 30-days mortality was 49% vs 25% before-COVID;in SCLC, it was 32% vs 18% before-COVID Updated data and treatment outcomes will be presented in the meeting [Formula presented] Conclusion: Lung cancer diagnosis has been affected during the COVID-19 pandemic with fewer cases diagnosed and more symptomatic disease compared to 2019, which seems to be associated with worse outcomes This study is still ongoing Keywords: NSCLC, SCLC, COVID-19