Lung Cancer Screening with Sputum Cytologic Examination, Chest Radiography, and Computed Tomography: An Update for the U.S.
Preventive Services Task Force

Figure. Follow-up ranged from 3 to 20 years among the 6 studies. The solid black squares represent Mantel–Haenszel weight.
Mortality in randomized, controlled trials of lung cancer screening with chest radiography with or without sputum cytologic
examination.
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Ann Intern Med
May 4, 2004
vol. 140
no. 9
740-753