In this issue of JAMA, Bach et al1 report their analysis of computed tomographic (CT) screening for lung cancer based on 3 single-arm studies, those from the Instituto Tumori in Milan, Italy, the Mayo Clinic in Rochester, Minn, and the Moffitt Cancer Center in Tampa, Fla. The investigators used a validated lung cancer prediction model to estimate the expected numbers of various lung cancer outcomes among the combined cohort of 3246 participants. To assess the effectiveness of CT screening, they then compared the observed numbers of lung cancer outcomes with the numbers of expected cases. They observed more than a 3-fold increase in the number of new lung cancer cases (144 observed vs 44.5 expected) and a 10-fold increase in lung cancer resections (109 observed vs 10.9 expected). However, there was no decrease in advanced lung cancer cases (42 observed vs 33.4 expected) or in lung cancer deaths (38 observed vs 38.8 expected).