Assessment of lung-cancer mortality reduction from CT Screening

BackgroundCT screening has been shown to increase lung cancer curability and we now assess the corresponding reduction in lung cancer mortality.MethodsLung-cancer mortality in a cohort of 7995 smokers who underwent CT screening for lung cancer in New York State (NYS) was compared with two unscreened cohorts (CPS-II and CARET). The standardized mortality ratio (SMR) of observed to expected lung cancer deaths for NYS was jointly adjusted for age, sex, and smoking history. As more current NYS smokers might have quit as a result of the screening, thus reducing deaths from lung cancer, another analysis was restricted to those participants smoking at entry and still smoking 6 years later.ResultsThe SMR was 64/99.8 = 0.64 (P = 0.84 × 10−4) and 28/77.6 = 0.36 (P = 0.83 × 10−10), showing a significant reduction in deaths from lung cancer of 36% and 64% for CPS-II and CARET, respectively. Considering participants who were smoking at entry and still smoking 6 years later, the SMR using CPS-II rates was 29/49.1 = 0.59 (P = 0.001) and using CARET rates it was 21/57.4 = 0.37 (P = 0.31 × 10−7).ConclusionsCT screening significantly reduces lung-cancer mortality.