Design and rationale of the ZORALCS study: An implementation study of lung cancer screening by low-dose computed tomography coupled to a smoking cessation randomized controlled trial in the Flemish region.

Background and objectivesLung cancer remains the leading cause of cancer-related death globally and in Belgium. Annual screening with low-dose computed tomography significantly reduces lung cancer-specific mortality in high-risk populations. Despite robust evidence supporting lung cancer screening, large-scale implementation in Belgium is still lacking. The 'Zuid-Oost Rand Antwerpen Lung Cancer Screening' (ZORALCS) study aims to evaluate the feasibility of introducing a regional lung cancer screening program in Flanders, specifically targeting high-risk adults with a history of heavy smoking. The primary objective is to assess the participation rate. Secondary objectives include evaluating each step of the screening and smoking cessation process.MethodsThe ZORALCS study is a 4-year, prospective, non-randomized, population-based feasibility study. It targets all adults aged 55-74 in the South-East Region of Antwerp (ZORA), inviting 25,885 individuals by regular post. Respondents who have smoked over 100 cigarettes in their lifetime complete an online questionnaire including the PLCO and HUNT risk prediction models. Those meeting risk thresholds (PLCO  1.51% or HUNT ≥0.64%) are invited to give informed consent and undergo annual low-dose computed tomography scans for 2 years. Local authorities, healthcare professionals, and digital support services assist participants throughout the process. Scans are read by radiologists with AI support, following the latest European guidelines. Participants who currently smoke or recently quit (<1 year) are enrolled in the 'TAbakoloog gestuurde of MInimale ROokSTOPinterventie bij longkankerscreening' (TAMIRO-STOP) randomized controlled trial to receive tailored smoking cessation support.Expected outcomesFindings will help identify barriers, guide policy development, and support future national lung cancer screening implementation.