The National Lung Screening Trial showed that three rounds of low-dose CT scan screening could reduce lung cancer mortality by at least 20%. The selection criteria for screening were ≥30 pack-years of smoking and <15 years since quitting for those who have quit. Taking into account additional risk factors, including ethnic group, level of education, body mass index, presence of chronic obstructive pulmonary disease, personal history of cancer, family history of lung cancer, and smoking intensity (average number of cigarettes smoked each day), and then applying the new model to the National Lung Screening Trial results, it appears that the new risk model would have missed 41% fewer cancers and increased the positive predictive value from 3.4% to 4%, without increasing the rate of false negatives significantly (Tammemägi et al., 2013). The hope is that refinement in the criteria for selecting subjects for screening will save more lives with fewer investigations for lesions that are not lung cancer.
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