Performance of community-based lung cancer screening program in a region with a high rate of endemic histoplasmosis.

58 Background: Lung cancer screening (LCS) with Low dose computed-tomography (LDCT) has been recommended by USPSTF for high-risk population since 2013 largely based on 20% relative reduction in lung cancer mortality shown in National Lung Screening Trial (NLST). The success of NLST was related to its high adherence rate and thorough ascertainment of lung cancers and deaths. This study evaluated performance of lung cancer screening program in Histoplasmosis endemic community. Methods: Demographic and clinical information was collected through retrospective review on all patients in the lung cancer screening program of a Kentucky health system comprising 21 centers from 2016 and 2017. A positive LDCT screen is defined as Lung-RADS version 1.0 assessment categories 3 or 4. Results: A total of 4500 LDCT screens were performed in 2016 (39%) and 2017 (61%) with 49% adherence rate to repeat annual screen in 2017. Mean age of patients was 64 years, majority being females (54%) and current smokers (69%) with average 52-pack year smoking history. The rate of positive LDCT was 13.3% (600) varying based on initial (14.6%) vs annual (9.5%) screen. A total of 70 lung cancers were diagnosed among all positive LDCT screens (11.7%) with a false positive rate of 12%. Conclusions: Comparing to NLST results updated with Lung-RADS categories, baseline positive screens in our community are similar (14.6% vs 13.6%, p = 0.15) despite being a Histoplasmosis endemic region. Our higher rate of annual positive screens (9.5% vs 6%, p < 0.001) and false positive rate (12% vs 8%, p < 0.001) may be explained by poor adherence to annual screens and an inability to thoroughly ascertain lung cancer diagnosis in all patients due to lost to follow up. In community setting with < 50% adherence to annual screens compared to 95% adherence in NLST, it is unclear if LCS mortality benefit still holds and needs intervention to increase adherence to LCS.