"Targeting of Low-Dose CT Screening According to the Risk of Lung-Cancer Death"  
NEJM Jul 18  
http://www.nejm.org/doi/full/10.1056/NEJMoa1301851?query=featured_home 
"CONCLUSIONS

Screening with low-dose CT prevented the greatest number of deaths from lung cancer among participants who were at highest risk and prevented very few deaths among those at lowest risk. These findings provide empirical support for risk-based targeting of smokers for such screening. (Funded by the National Cancer Institute.)"