Detection of early cancer by lung cancer screening

A total of 1,615,010 person-years in 64 local municipalities were screened from April 1982 through March 1990. All participants were screened annually by chest X-ray, and participants of high risk group were screened by both chest X-ray and sputum cytology. 76,522 person-years(4.7%) were screened by sputum cytology. Among 148 lung cancer patients(0.194%) detected by sputum cytology, 132 were squamous cell carcinoma, and 116(78%) were chest X-ray negative. 90 patients were proved to be Stage 0 or I after resection, and 47 were less than 10 mm in diameter. On the contrary, 166 out of 432 detected patients detected by chest X-ray only, were proved to be Stage I after resection, and 4 patients were less than 10 mm in diameter. Thus, sputum cytology for high risk group were effective to detect early lung cancer.