Overview of observational studies of low-dose helical computed tomography screening for lung cancer.

OBJECTIVE: Lung cancer is a substantial public health problem in Western countries. Evidence from previous controlled trials of chest radiography and sputum cytology does not support lung cancer screening, but computed tomography (CT) screening has recently emerged as a more sensitive screening tool. For the present article, the available observational studies of low-dose helical CT screening for lung cancer were reviewed. METHODOLOGY: An evidence-based review of all published observational studies of low-dose helical CT screening for lung cancer, identified by an extensive search of Medline, was conducted. RESULTS: Eight observational studies of CT screening for lung cancer were identified. Relative to chest radiography, low-dose helical CT is a sensitive screening tool and can detect a high proportion of small lung cancers at an early and resectable stage. The yield of sputum cytology in addition to CT screening appears to be relatively low. To date, 5-year lung cancer survival of all individuals participating in baseline screening has not been reported for any of the studies. CONCLUSIONS: Although these preliminary studies are very promising, it remains to be proven that the early detection and treatment of lung cancer will lead to a reduction in mortality. This issue will be addressed by randomized controlled trials. In the interim, the long-term follow up of these observational studies could provide further insights.