A pilot study of lung cancer screening with low-dose spiral CT

We performed a pilot study to evaluate the efficacy of lung cancer screening with low-dose spiral CT (CT screening) from June to December 1996. Volunteers from participants in conventional lung cancer screening with computed radiography and sputum cytological assessment (CR screening) in the same period were enrolled into this study. CT scans of the chest were made in a single breath-hold with low-dose spiral CT for lung-cancer screening. Overall 431 individuals (22.9%) out of 1,880 participants were judged to need further examinations by either conventional or CT screening. Two hundred and ninety eight individuals (15.9%) of them were classified as ''e'' judgement which means possible or probable lung cancer by CT screening. Then 418 individuals had further examinations. Eight cases were diagnosed as having lung cancer (detection rate: 0.43%), of whom only two cases were detected by CR screening. Therefore, the positive predictive value in CT screening was 0.027. All cases had adenocarcinomas, located in peripheral lung regions. The mean diameter of tumors was 17 mm (range 8-25 mm) and three small cancers less than 10 mm were detected. There were 5 stage IA cases, 1 stage IB case, 1 stage IIIA case and 1 stage IV case. Six patients with stage IA or IB disease underwent surgical treatment. It was suggested that low-dose spiral CT was superior in the detection of peripheral lung cancer and is a promising tool in lung cancer screening. It is necessary to establish a system of annual CT screening and the method of comparative reading of CT scan in order to improve the positive predictive value of CT screening. (author)