Results of Sputum Cytology in Lung Cancer Screening by the Miyagi Program

Abstract

Participants who were 50 years of age or older and with a cigarette index of 600 or more were screened annually by both sputum cytology and chest X-ray for the early detection of lung cancer in the Miyagi Program. From 1982 to 1986, 45, 865 person-years were screened. Among 128 men with sputum specimens considered to be positive for cancer cells, 92 cases of lung cancer and 7 cases of upper respiratory tract cancer were confirmed. Among 146 men with sputum spicimens showing susupicious cells or borderline atypical cells, 23 lung cancer were confirmed. One hundred and six cases of these 115 lung cancer cases detected by sputum cytology were squamous cell carcinoma. Among 146 cases of lung cancer detected by dual screening, 92 were detected by sputum cytology only, 23 were detected by both cytology and chest X-ray and 31 were detected by X-ray only. Not only early squamous cell carcinomas of the hilar type but also occult lung cancers located in sub-subsegmental or more distal portions of the bronchi were detected by sputum cytology. The prevalence rate per 1, 000 by the initial screening was 3.4.: 2.2 by cytology only, 0.7 by X-ray only and 0.4 by both examination. The detection rate of lung cancer by sputum cytology at the third or later screening decreased to about a half of the prevalence rate.