BACKGROUND: Lung cancer screening (LCS) with low-dose computed tomography (LDCT) reduces mortality. Ireland will likely adopt a national screening programme in the coming years, and evidence on the size of the eligible population is required to inform planning.

OBJECTIVE: The objective was to estimate the number and characteristics of individuals in Ireland eligible for LCS under different international criteria and to project future uptake.

METHODS: We combined population data from the 2022 Census and subsequent projections with smoking history from the 2017 Eurobarometer survey. Eligibility was assessed under four criteria: Irish pilot (55-74 years, ≥ 20 pack-years, quit < 15 years), US Preventive Services Task Force (USPSTF) 2013, USPSTF 2021, and NELSON. Projections to 2045 accounted for demographic change and smoking trends. Expected uptake was estimated using participation rates from SUMMIT, a large UK LCS implementation trial.

RESULTS: In 2022, 245,105 individuals met the Irish pilot criteria, and 345,328 met USPSTF 2021. Eligibility remains broadly stable until the mid-2030s, then declines across all criteria. Relative differences between criteria persist over time, with USPSTF 2021 consistently identifying the largest group. Applying SUMMIT uptake rates, around 36,000 LDCT scans annually would be required at steady state.

CONCLUSIONS: Approximately a quarter of a million people in Ireland would currently be eligible for LCS, rising to more than 340,000 under broader criteria. Numbers are expected to remain high for the next decade before gradually declining. These findings provide key evidence for service capacity planning and highlight the importance of flexible programme design to meet future demand.