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I I I t I I I I I I I I I I I I ANALYSES OF RELATIONSHIP BETWEEN SMOKING, PASSIVE SMOKING AND LUNG CANCER CELL TYPE Cha Oing, Chen Yong-zhong and Du Ying-xiu Department of Hygiene, Guangzhou Medical College, Guangzhou, China It is generally believed that different factors may be associated with different lung cancer cell types. Active smoking has been reported to be closely associated with squamous cell carcinoma (SC). Since the composition of mainstream smoke is considered to be similar to sidestream smoke, it may be proposed that if ETS exposure is associated with lung cancer, the major cell type ought to be squamous cell carcinoma. In the city of Guangzhou (population two million), a total of 5,546 (M:3,760, F:1,786) lung cancer deaths were recorded between 1980 and 1988. One thousand ninety-three cases (M:804, F:289) had a definite histological diagnosis and smoking history plus history of smoking by live-in relatives. Each lung cancer death was investigated using a standardized questionnaire, which was administered by trained medical personnel. Information concerning smoking of the patients was obtained retrospectively from live-in relatives and checked for accuracy using hospital records. Analysis of the relationship between smoking and lung cancer cell type shows that SCc is higher in smokers than in nonsmokers in both males (P<0.01) and females (P<0.01). In nonsmokers, adenocarcinoma (AC) is more prevalent in both males (P<0.05) and females (P<0.01), compared to smokers. For analysis of active smoking and lung cancer cell type in males and females, a smoking index (cigarettes per day x years of smoking) was used as a quantitative measure (<200, 200+, 400+, 600+), and five lung cancer cell types were identified (squamous, small, adeno, large and other). The data suggest a dose-response relationship between the smoking index and squamous cell carcinoma in males only W = 13.8, p < 0.01). Over 94% of male lung cancer deaths were in smokers; therefore, passive smoking and cell type was analyzed in females only. Lung cancer deaths were grouped into four groups: active smoking (AS) only, passive smoking (PS) only, AS+PS, and Non AS+ Non PS. The data suggest no difference in ratio of lung cancer cell type among the groups (X2=1.84, P>0.05). In summary, smoking status was associated with a high incidence of squamous cell carcinoma; however, such an increase was not observed in the group exposed to passive smoking. O 00 ~ -4 tb O P I