Lung cancer screening with low dose CT (LDCT) allows diagnosis of lung cancer in early stages as well as improved survival. The selection of patients at risk is crucial in order to optimize the resources and outcomes of the screening programs. Actual recommendations for screening include age (50 to 80 years-old) and smoking burden. Objective: To assess the risk for cancer and associated factors within a 20-year running program (P-iELCAP, Spain) specifically in patients with <55 years or >80 years.  Results: 4162 patients participated in the lung cancer programme from 2000 to 2022, with 17075 LDCTs performed. PFTs were performed in 2552 patients. At enrolment, 1864, 2265 and 33 patients were <55, 55-80 (reference group), and >80 years-old respectively. Frequency of cancer diagnosed at first round (prevalent) and compared to reference group (1.32%) was 0,21% (p<0,001), and 6.06% (p=0.079), respectively. During the whole period of study, there were 143 diagnoses of cancer in 124 patients: 13 in <55, 104 in 55-80, and 7 in >80 years-old. The presence of emphysema on CT had significant risk for cancer in the whole group after adjusting for age and pack-years (OR 2.078; 95%CI 1.46 ? 2.956; p<0.001), but emphysema had a particularly high OR for lung cancer of 14.79 (95%CI 3.45 - 63.7), p<0.001 in <55 years. A value of DLCO<90% adjusted for age and pack-years also had an OR of 1,847 (IC95% 1,022 ? 3,338; p=0,042). Conclusions: Lung cancer risk is associated with age, smoking burden, and emphysema, this latter particularly in younger subjects. A DLCO<90% portends a higher risk for cancer and might be considered as a tool for assessing lung cancer risk before screening enrolment.