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I I I I I I I I I I I I I I I I I ANALYSIS OF THE RELATIONSHIP BETWEEN SMOKING AND LUNG CANCER Xie Cai-liang, Yang Wei-hua, Lian Ruan-shen, Huan Xia and Yang Xiao jian Shanxi Tumor Hospital, Shanxi, China We analyzed the relationship between smoking and lung cancer. One thousand one hundred seven lung cancer cases were admitted into our department from January 1982 to December 1989; 819 were histologically and/or cytologically diagnosed. Of the latter, 760 were male (86 non-smokers) and 59 were female (56 non-smokers). The mean age was 54.2 years (16 to 76 years). The smoking rate of all lung cancer patients was 82.66% (88.86% for males, 5% for females). Among the smokers, 278 were squamous cell carcinoma (SCC) (40.28%), 186 were adenocarcinoma (AC) (27.47%), and 177 were undifferentiated cell carcinoma (UCC) (26.14%). Among the non-smokers, 25 were SCC (17.6%), 64 were AC (45.07%) and 47 were UCC (33.1 %). In female non-smokers, 9 were SCC (11.9%), 27 were AC (48.2%), and 16 were UCC (28.6%). Among the smokers, 112 were under 45 years (16.5%), and 565 were over that age. In the 45 years or older group, SCC, AC and UCC comprised 91 %, 80.6 % and 72.3%, respectively. The age of morbidity for SCC is later than for the other two types. The younger the age of starting smoking, the higher the incidence of lung cancer. Smoking rates before 29 years of age in SCC, AC and UCC are 74.8%, 70.4%, and 77.8%, respectively. In those who smoked no more than 30 years, the incidence of AC, SCC and UCC was 52.7%, 29%, and 46.9% respectively. The latency period for SCC was the longest. A dose-response relationship for each type of lung cancer, SCC, AC and UCC, in those whose index of smoking was 400 or more, was found in 82.6%, 74.2%, and 73.8%, respectively. When the relationship between different histologic types of lung cancer was analyzed with respect to: starting age of smoking, smoking duration, and amount smoked, an apparent dose-response relationship between SCC and the above indices of exposure, was found. There are significant differences between SCC and AC or UCC (P<0.01), Most of AC patients are non-smokers, which suggests a stronger relationship between smoking and SCC and UCC. The latency period for the three kinds of lung cancer after starting smoking is 20 years or more. I