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t I I I I I I I I I I I I I I I I I ANALYSIS OF LUNG CANCER RISK FACTORS IN GUANGZHOU CITY, CHINA Chen Xiao-wei, Lei Yi-xiong and Du Ying-xiu Department of Hygiene, Guangzhou Medical College, Guangzhou, China According to national health statistics, the mortality rate for lung cancer in Guangzhou city is the third highest in China. Lung cancer is the leading type of all malignant tumors in Guangzhou city. In order to investigate potential risk factors for lung cancer in Guangzhou city, retrospective studies of 6812 lung cancer deaths were conducted during 1980 to 1988. After excluding non-primary lung cancer deaths and deaths of those who had lived in the city less than 10 years, data on 5546 primary lung cancer deaths were analyzed. Some cases were included in a case-control study. The results of the studies show that: 1) Smoking is a risk factor for lung cancer in Guangzhou city. The rate of smoking is as high as 93% in males and the relative risk (RR) is 3.54 (95% CI 2.44-5.11, P<0.001). The RR is 1.93 in females (95% CI 1.30-2.87, P<0.01). 2) The lung cancer mortality rate is correlated with atmospheric pollution. When the atmospheric pollution index or the location of a source of pollution near homes was analyzed, air pollution was found to be most severe in Liwan district, and corresponded to the highest rate of lung cancer death. 3) The lung cancer mortality rate was related to some occupational exposures. For males, workers exposed to chemicals have the highest standarized mortality rate (SMR), with higher rates in cargo handlers, cooks, mechanics, and construction workers as well. In females, the highest SMR is found in those who often do housework. 4) The incidence rate for lung cancer is related to some types of chronic lung diseases such as tuberculosis (P<0.01). However, the relationship between chronic bronchitis, emphysema and lung cancer also should be more closely examined. 5) It seems that the etiologic factors for lung cancer are different in males and females. In males, smoking is the main risk factor; and in females, besides smoking, exposure to coal fumes (RR 2.21, 95% CI 1.16-4.21, P<0.01) is an important risk factor. The relationship between indoor air pollution and lung cancer in males is unclear; 6) The cell type differs in the deaths of males and females. In males, it is squamous cell carcinoma that has the highest ratio (58%), but in females, it is adenocarcinoma (49%). Usually it is considered that smoking will induce squamous call carcinoma. Thus, in addition to smoking, it seems that there exists another adenocarcinoma inducing factor in women. I