Tobacco Documents Online

I I I I I I 1 I I I I i I I I I ANALYSIS AND ESTIMATES OF ATTRIBUTABLE RISK FACTORS FOR LUNG CANCER IN NANJING, CHINA Shen Xiao-bine*, Wang Guo-xiong*, Huang Yuan-zhu**, Xiang Long-sheng* and Wang Xing-he* *Nanjing Railway Medical College, Nanjing, China **Nanjing Medical University, Nanjing, China Abstract This is a case-control study of 83 cases of primary pulmonary squamous cell carcinoma and 180 cases of primary pulmonary adenocarcinoma in Nanjing. Multivariate conditional logistic regression analysis shows five risk factors for pulmonary squamous carcinoma. These were: smoking, cooking fume pollution, family tumor history, type of fuel used in the home, and use of coal stove for heating in winter. The relative risks (RR) for these five risk factors were 1.03 (95 % CI, 1.00-1.06), 3.81 (95 % CI, 1.06-13.73), 5.61 (95 % CI, 1.23-25.79), 4.97 (95 % CI, 0.8-30.88), 3.72 (95 % CI, 0.88-15.71), and the respective population attributable risks (PAR) were 0.6823, 0.5156, 0.2772, 0.5465, 0.3611. The four risk factors of pulmonary adenocarcinoma were smoking, cooking fume, chronic bronchitis, family tumor history. The respective RRs were 1.01 (95% CI, 1.00-1.03), 2.99 (95% CI, 1.68-5.34), 2.49 (95 % CI, 1.68-5.34), 4.77 (95 % CI, 1.93-11.83, and the respective PARs were 0.1987, 0.4699, 0.1763, 0.1844. The combined PAR of the five risk factors for pulmonary squamous cell carcinoma was 0.9431 and the combined PAR of risk factors for pulmonary adenocarcinoma was 0.7895. Among malignant tumors, lung cancer has become one of the most threatening to human health. The lung cancer death rate in China shows an apparent rising trend in recent years.(1) Squamous cell carcinoma and adenocarcinoma are the two major histopathological types of lung cancer. To examine the risk factors for squamous cell carcinoma and adenocarcinoma we have conducted a matched case- control study of risk factors for pulmonary squamous carcinoma and adenocarcinoma in Nanjing. Selection of Cases Materials and Methods Diagnosed primary lung cancer cases were obtained from Nanjing Municipal Hospitals from 1986 to 1993 and were Nanjing residents for longer than 20 years. A total of 83 pulmonary squamous carcinoma and 180 adenocarcinoma cases was included in the study. Selection of Controls Healthy controls were selected from over-20 year, tumor-free Nanjing residents. They were matched 1:1 with cases by sex, age (± 5 years), nationality, and street address. O I N O ~ -4 O ~ O ~ I

Data Collection The standardized questionnaire utilized information in the literature and incorporated features uniquely found in the local population and environments. Table 1 contains coding information methods and assigned values of data. Methods of Analysis Squamous carcinoma and adenocarcinoma risk factors were analyzed by conditional logistic regression; the risk factors were then subjected to analysis to estimate attributable risk(2-4). Table 1. Coding and Value Assignment of Data v.da6k . Focroc ~ ... .. : A+/1~1Dn vuiu Xl Sml®g mdex Amamt ma4ed (clgercua pcr d.y) x ycan of mol 20 X2 Degee of mhilatim' qg No: 0; SlWlavr: 1-Medium; 2-Deep: 3 , 30 Pasdvc nmolmig Nn: 0; Ya: I X4 Omryxtlooil expm¢e to cool®g Bme No: 0; Ya: 1 X5 Hubry of b[aoAd" No: 0; Yes: I X6 Humry of mCereWais Na: 0; Ya: I X7 Fwily - lti4ay No: 0; Yes: I X8 L'n•hy ryece avaage Ovmg am m lau 20 yon X9 Type of fwA in the tme (fisl "mdex)'• Noo-eolid fuel: 0; 3olid Nel: I XI0 Cod >ture for wmmr Icatiqg No: 0: Ya: I Xl1 Oil emnmpem m caok'mg eonS.p6oo per pecsm pa moNh X12 2GrcLm cooi®g fume po1WGm No: 0; Ya: I X13 Regder cmwmpim of fried food No: 0; Ya: I X14 Cooking m0ex Avenge times of cookmg per week Note: • Shallow: exhale by mouth; Medium: exhale by nose; Deep: swallow smoke. *• Based on data of last 20 years. Results Multivariate risk analysis A multivariate analysis was performed by conditional logistic regression model. Risk factors for pulmonary squamous carcinoma and pulmonary adenocarcinoma were analyzed respectively, using one- side test with a=0.05. Results are shown in Table 2 and Table 3. -2- I I I I I I I I I I I

I I I 1 I I 1 I I 1 Table 2. Results of Conditional Logistic Regression Analysis in Pulmonary Squamous Carcinoma Group s1aMUA Fira.of . . . . ReB~~. ' . Regrcasim Relativc . Fscbr CoeB'icies Coeffici<K. . P Velec - Risle 95A Cl Cooking fwsa 1.3386 0.6536 0.0203 3.81 1.0G13.73 Smahg udex 00334 0.0132 0.0056 1.03 1.01-1.06 Family e®ar biswry 1.7275 0.7767 0.0132 5.61 1.29-25.79 Fuel type 1,6027 0.9324 0.0428 4.97 0.8130.88 Cwl Sbve fm healmg 1.3134 0.7352 0.0370 3.72 0.88-15.71 Table 3. Results of Conditional Logistic Regression Analysis in Pulmonary Adenocarcinoma Group sumudEraeof... . . R<gnalbn ReStMWrt ....: . PactOr CocRSeiept . . /bel&!ett ' . P Va6M ReWAv9 KkR .. 43% Q " Smokmg mdex 0.0123 0.0065 0.0300 1.01 1.000.1.03 Claan'a: brmchiue 0.9133 0.3A11 0.0037 2.49 128d.ee Coolung 6mes 1.0967 0.2956 0.0001 2.99 L68S.34 Family nmma hisrory 1.5622 0.4621 0.0004 4,77 1.93-11.83 Estimate of population attributable risk After various risk factors were identified, the RR of the factors was calculated and the respective PAR and SAR were estimated. (Table 4) I I I - N O O i V O CA) I O w 1

Table 4. Population Attributable Risks of Lung Cancer Risk Factors Pwmmary sq~ Cea caremcros . Puunmaxjr naeuocntr6mn..-.. .. MumticoP N®ber.of Facox [<vd RR d.w B1l. ,.Catte. ...~ PAtt. . Smo¢in8 Wcx Mexnueleot 1.0340 83 0.6829 1.0124 ISO 0.1987 Coolmg Fm¢s 0 1 25 1 53 1 3.8138 58 0.5156 2.9943 127 0.4699 Chraoic 0 1 12] Bnmchtrix 1 2.4925 53 0.1763 Family T~ 0 1 55 1 138 Hiurory 1 5.6135 28 0.2R2 4.7693 42 0.1844 Coel S[we fm 0 1 42 H•,tb~g 1 3.7187 41 0,3611 FS~eI Ndex Meamcemeot 4.9665 83 0.5465 SAR• 0.9431 0.7895 Syudutlc PopWatieu Atln'buable Risk Population attributable risk (PAR) is a measure of the relative risk of a given factor. For a given risk factor, PAR depends on the relation risk of the magnitude of exposure to that factor.(4,8) As seen in Table 4, the main risk factors for pulmonary squamous cell carcinoma were smoking, type of fuel used in the home, cooking fumes, coal stove use for winter heating, and family tumor history; the risk factors for pulmonary adenocarcinoma were, in their order of significance, cooking fume, family tumor history, chronic bronchitis and smoking. Discussion Most studies show that smoking has different effects on various types of lung cancer. Our study shows that smoking is a major risk factor for squamous cell carcinoma in the lung, with a PAR of 68.23 %. But the PAR of smoking for pulmonary adenocarcinoma was 15.6%. Passive smoke was not found to be one a risk factor. In a separate case-control study involving 70 nonsmoking females with adenocarcinoma, exposure to passive smoke from >20 cigarettes/day had a relative risk of 0.85, 95% CI 0.26-2.74 (data not shown). Cooking fumes are the vapor-phase product of cooking and result from pyrolysis of cooking oil and food under high heat. Since Chinese traditionally cook with high temperatures, cooking fumes are one of the major indoor pollutants. We have tested the chemical composition of cooking fumes for their genetic toxicity and found them to contain benzo(a)pyrene and benz(a)thracene. Toxicology experiments -4- I I I I I I I I I I 1 I J

I I I I I I I I I I I also confirmed the mutagenicity of the contents of cooking fume. Our study found cooking fumes to be a common risk factor for both squamous carcinoma and adenocarcinoma in the lung. The respective relative risk was 3.8138 and 2.9943 and the respective PAR was 51.56% and 46.99%. Therefore, control of cooking oil-food pyrolysis and improvement of kitchen exhaust systems should be emphasized. At present, many urban residents of China still use coal and charcoal as fuel for daily living, and in winter coal stoves are used for heating. These are primary causes of indoor air pollution. Our study shows a close relationship between coal stove use and lung squamous cell carcinoma. Family tumor history is also a common risk factor for both squamous cell carcinoma and adenocarcinoma of the lung. Those with family history of tumor should avoid being exposed to other risk factors. Chronic bronchitis is related to the occurrence of pulmonary adenocarcinoma with RR value of 2.4124, and PAR value of 0.1724. Therefore, timely treatment of respiratory disease may help to reduce incidence of pulmonary adenocarcinoma. ~ ~ N O CD ~ ~ 00 -5- W ~ 0 ~ tr ~

References 1. National Environment Protection Bureau, "Environment of China 1991," J. of Chinese Environment 6(2): 1992. 2. Whittemore, A.S. "Estimating Attributable Risk from Case-Control Studies," Am. J. Epidemiol. 117: 76-85, 1983. 3. Walter, S.D. "Effects of Interaction, Confounding and Observational Error on Attributable Risk Estimation," Am. J. Epidemiol. 117: 598-604, 1983. 4. Bruzzi, P., et al. "Estimating the Population Attributable Risk for Multiple Risk Factors Using Case-Control Data," Am. J. Epidemiol. 122: 904, 1985. 5. Levin, M.L. "The Occurrence of Lung Cancer in Man," Acta. Intern. Cancer 19: 531-41, 1953. , I I I I I I I I I I