ObjectiveThe study objective was to determine what proportion of asymptomatic patients had resectable lung cancer detected through lung cancer screening versus incidentally. MethodsWe performed a retrospective study of patients who underwent resection for lung cancer between January 2015 and December 2020. We then assessed whether asymptomatic patients with incidentally found lung cancers were eligible for lung cancer screening using the National Comprehensive Cancer Network, United States Preventive Services Task Force, Centers for Medicare & Medicaid Services, American College of Chest Physicians, American Cancer Society, and American Society of Clinical Oncology guidelines. ResultsOf 539 patients who underwent resection for primary lung cancer, 437 (81%) were asymptomatic and 355 (66%) of these patients had lung cancer found discovered incidentally. Of the 355 patients with incidentally detected lung cancer, 10 were excluded for insufficient data. Of the remaining 345 patients, 110 (32%) would have been eligible for screening using National Comprehensive Cancer Network guidelines, 65 (19%) using 2021 United States Preventive Services Task Force guidelines, 53 (15%) using 2013 United States Preventive Services Task Force guidelines, 64 (19%) using 2022 Centers for Medicare & Medicaid Services guidelines, 52 (15%) using 2015 Centers for Medicare & Medicaid Services/American College of Chest Physicians guidelines, and 45 (13%) using American Cancer Society/American Society of Clinical Oncology guidelines. Of the 280 patients who were screen ineligible by 2021 United States Preventive Services Task Force criteria, 143 patients (51%) never smoked, 112 patients (40%) quit smoking more than 15 years ago, 89 patients (32%) did not smoke at least 20 pack-years, and 44 patients (16%) were ineligible due to age. ConclusionsThe majority of asymptomatic patients with resectable lung cancers had lung cancer identified incidentally and not through lung cancer screening. Most of these patients were not eligible for screening under current guidelines. This study suggests a need for improved lung cancer screening implementation and further investigation in the identification and assessment of risk factors for lung cancer.