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I I I I I I .1 I I I I I I I I I COMBINED ANALYSIS OF CASE•CONTROL STUDIES OF SMOKING AND LUNG CANCER IN CHINA Yu Shun-zhane and Zhao Ning Shanghai Medical University, Shanghai, China Introduction Despite the fact that adverse health effects of smoking have been well known for many years, smoking continues to increase in China. According to a survey of 0.5 million people, the smoking rate for males ?20 years old was 68.9%. A large percentage of the population smoke and 1,400 billion cigarettes are consumed annually. In some cities and counties lung cancer is the leading cause of death. Methods By surveying and screening the literature, 15 case-control studies on active smoking and 3 case- control on passive smoking were selected and analyzed. The total numbers of lung cancer cases were 6,085 and there were 6,328 controls. Using meta-analysis, we applied the fixed and random effects models to test for their heterogeneity according to (Peto, DerSimonian and Laird), the pooled Odds Ratios (ORs), and 95% Confidence Intervals (95%CI). The pooled Population Attributable Risk (PAR) was calculated by the method of Levin and Bruzzi, and the Mantel test was used for trend. Results 1. The proportion of smokers among the lung cancer cases and controls was 69.09% and 31.15 % respectively. 2. The pooled OR (smoking vs nonsmoking) was 2.19 (95%CI 2.03-2.37) and the pooled PAR was 33.64%. There were no significant differences between males (OR=3.01, 95 %CI: 2.63-4.46) and females (OR=2.32, 95 %CI: 2.02-2.66). According to exposure rates, PAR were 56.84% for males and 33.10% for females. 3. The number of cigarettes smoked, the smoking duration, and the age of beginning to smoke were correlated with an elevated Odds Ratios of risk for lung cancer. There was a significant trend for amount of cigarette consumption: for example the OR=1.00 for nonsmoking, OR=1.24 for < 10 cig./day, OR=2.19 for 10-19 cig./day, and OR=4.47 for z 20 cig/day. Chi-square (X2) for trend was 223.13 (P<0.01). 4. Smoking is associated with squamous cell carcinoma (OR=4.79, 95%CI 4.02-5.70) but not adenocarcinoma (OR= 1.02, 95%CI: 0.87-1.20). , 5. Although passive smoking has been suggested to be an important risk factor for lung cancer, p the OR was 1.004 (95 %CI: 0.74-1.85) and, therefore, not statistically significant, and the PAR was only j 0.16% in this data set. -1 tb 0 0 tn I

I Conclusion Unless measures are taken to control cigarette consumption, deaths due to chronic disease, including lung cancer, will increase rapidly. -2- I I I I I I I I I I I I I I , '