MASS-SCREENING FOR LUNG-CANCER WITH MOBILE SPIRAL COMPUTED-TOMOGRAPHYSCANNER

Background The incidence of and mortality from lung cancer have increa sed steadily. Most lung cancers are not localised when first detected, but early detection is mandatory to improve prognosis. Since curable early cases are hard to visualise with conventional chest radiography, a new diagnostic means must be found. We assessed whether population- based mass screening with a spiral computed tomography scanner could c ontribute substantially to detection of smaller cancers, and decrease mortality. Methods In 1996, we screened in a mobile unit 5483 individu als from the general population of Matsumoto, Japan, aged between 40 y ears and 74 years who had undergone annual chest radiography (miniatur e fluorophotography) and cytological assessment of sputum. All partici pants had a low-dose X-ray spiral computed tomography (CT) scan of the thorax; 3967 also underwent miniature fluorophotography. We compared smokers and non-smokers. Further assessments were done for probably be nign but suspicious lesions; suspicion of cancer; and indeterminate sm all nodules by chest radiography and conventional CT, with additional transbronchial biopsy when possible. Thoracotomy was recommended when it was strongly suspected that the patients had lung cancer. Findings 19 patients were diagnosed as having lung cancer--14 with suspicion of lung cancer, three with benign but suspicious lesions, and two with i ndeterminate small nodules. 18 cases were surgically confirmed, and on e was clinically diagnosed. The mean size of lesions was 17 mm (range 6-47). In four of 19 patients, lung abnormality was seen on CT and min iature fluorophotography, The lung-cancer detection rate with CT was 0 4846, significantly higher than the 0 03-0 05% for standard mass asse ssments done previously in the same area. CT missed one case that was found solely on a sputum cytology examination. Interpretation Our resu lts show that miniature fluorophotography or conventional chest radiog raphy, which have been the main diagnostic techniques for lung cancer, showed few small cancers. CT was more accurate in mass screening for lung cancer and led to early detection and an accurate diagnosis of lu ng cancer, and should be considered in future health plans.