Mortality benefit from LDCT lung cancer screening

Thesis (Master's)--University of Washington, 2017-08Introduction: The estimated mortality benefit to current and former smokers of cigarettes from annual lung cancer screening with low dose helical computed tomography (LDCT) is based largely on data obtained from the National Lung Cancer Screening Trial (NLST). As this trial focused on the cumulative benefit at the end of 3 annual rounds of screening, the mortality benefit associated with continued LDCT screening beyond 3 rounds may not yet have been accurately characterized. Methods and Results: Time-specific mortality rate ratios were calculated using the NLST data to delineate the yearly mortality benefit. The mortality reduction from LDCT screening was evident by the end of the first year after initial screening and remained consistent at about 20 percent across the years in which there was continued screening. Beginning at about 4 years after screening had ended, lung cancer mortality among persons in the LDCT screening arm of the trial rose to the levels among persons in the control arm. Conclusions: The aggressive nature and short latent period of lung cancer likely account for the early mortality benefit with just one round of screening. The annual 20% relative mortality reduction in lung cancer from the NLST trial seems to be an accurate representation of the mortality benefit patients may experience from continued yearly LDCT screening even after 3 rounds