Abstract
Mass screening for lung cancer based on radiologic and sputum cytologic examinations was begun in 1981 by the Osaka Lung Project. In this report, we present the results of further examinations and of follow-up studies of the cases identified as category D or E by sputum cytologic examinations during the 10-year period from 1981 to 1990. Sputum specimens were obtained from 16, 992 acceptable high-risk persons, amon which 16, 795 (98.8%) specimens were satisfactory. A total of 402 cases underwent further examinations and 28cases of primary lung cancer were confirmed. Thus, the positive predictive value of sputum cytologic examination was 6.97%. Fifty-three of the 16, 795 sputum specimens were fond to have category D and 14 were found to have category E. Primary lung cancers were confirmed in 14case reported as D. The positive predictive value for category D was thus 26.42%. Nine cases reported as E were confirmed, the positive predictive value being 64.29%. Twelve (85.7%) of 14 cases reported as D and 2 (33.3%) of 6 cases reported as E were detected in clinical stage I. Thus, the freqency of stage I lung cancer was higher in D. Ten out of 14 cases reported as D were found to have lung cancer by sputum cytology only and all were detected in clinical stage I. After 5years of follow-up, 2 of 3 cases reported as E could not confirmed as having either lung orlaryngeal cancer and were thus considered to be false positives.
