a, Diagram describing exclusions made in our analysis. b, Table describing exclusions made by the NCI when selecting images to release from NLST. Note that there were 623 screen-detected cancers but a total of 638 cancer-positive patients. The additional 15 patients were diagnosed during the screening window, but not due to a positive screening result. In this case Row 3 ‘Relevant Images’ meant that, for cancer-positive patients, there were images from the year of the cancer diagnosis, and for cancer-negative patients it meant that all 3 years of screening images were available. Note that the publicly available version of NLST downsampled the screening groups 3 (no nodule, some abnormality) and 4 (no nodule, no abnormalities). In Extended Data Figs. 2, 3, 4 and Supplementary Table 4 we present another version of the main analysis that compensates for this downsampling by upweighting patients within these groups.