The National Lung Screening Trial (NLST) compared low-dose CT screening to chest x-ray (CXR) screening for lung cancer in high-risk individuals. Over 53,000 participants were randomized to receive either low-dose CT or CXR screening annually for three years. The primary endpoint was lung cancer mortality. An interim analysis found that low-dose CT screening reduced lung cancer mortality by 20% compared to CXR, with fewer advanced stage cancers detected in the CT group. However, the false positive rate was high at around 95% for both screening methods.