Determination of the optimal screen interval in low-dose CT lung cancer screening: are we there yet?

In view of the prospective results of the largest randomized controlled lung cancer screening trial worldwide, the National Lung Screening Trial (NLST), and baseline results of other trials, interest in low-dose chest CT for lung cancer screening in high-risk individuals is increasing. In 2011, the U.S. NLST demonstrated that screening using annual low-dose chest CT reduces lung cancer mortality by 15–20% compared to screening by chest radiography (1). This result was translated by several U.S. medical associations, including the U.S. Preventive Services Task Force, into a recommendation to screen subjects at high-risk for developing lung cancer by annual low-dose chest CT (2-5). According to the recommendation of the U.S. Preventive Services Task Force, all individuals between 55 and 80 years old who smoked at least 30 pack-years and quit not longer than 15 years ago are eligible for lung cancer screening. Screening should be discontinued once a person has not smoked for 15 years or develops a health problem that substantially limits life expectancy or the ability or willingness to have curative lung surgery (5).