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f 1988 Eisevier~Science Publishers B.Y. (Biomedical Division) Smoking and health 1987. M. Aoki,n all editors PASSIVE SMOKING AND LUNG CANCER IN WOMEN REIKO INOUE, TAKESHI HIRAYAMA* Kanagawa Cancer Center, Asahi-ku, Yokohama 2411, Japan Institute of Preventive Oncology, Shinjuku-ku, Tokyou 162, Japan• INTRODUCTION A case-control study on smoking and lung cancer was conducted in two cities in Kanagawa prefecture Japan distinctly different in social environment ( Kamakura and Miura, featured by residential community and fishery industry respectively). A significant dose-responce relationship was observed between the number of ciga- rettes smoked daily and the risk of lung eancer. The risk of lung, cancer was sig- nificantly higher, the earlier the age at start of smoking.These results clearly explain the reason of the rapid increase in lung cancer mortality in recent years in men. The increase in lung cancer mortality in woeeen, however, is difficult to be explained by the influence of active smoking only, because the majority of lung cancer patients are non-smokers in case of women. Therefore passive smoking has come to be suspected as the possible causative factor of lung cancer in women. Epidemiological studies thus for reported since 1981y mastly suggest such possibi- lity (1-7). Therefore the role of passive smoking on lung cancer in women was ex- amined in the present case-control study. MATERIALS AND METHODS Husbands smoking habit of 37 cases of women died of lung cancer in Kamakura and Miura (13 cases in Kamakura, 1980-1983 and 24 cases in Miura, 1973-1981) were compared with 74 cases died of cerebrovascular disease during the same period. The cases and the controls were matched to age (year of birth), year of death (s 2.5 years) and the district. Cerebrovascular disease cases were selected as cont- rols because the disease is known to be related neither to active nor to passive smoking. Interviews were conducted~by trained1ocal public health nurses and mid- wives using standard questionnaires.ldantel-Haenszel odds ratio was calculated: for relative risk (r.r.), with 90% confidentiai intervals. RESULTS Active smoking (direct smoking). 24.3% of women smoked in case group (smokers 9, non-smokers 28), and 16.2% smo- ked in control group (smokers 12, non-smokers 62), relative risk (r.r.)(M.H.0dds ratio) being 1.66 (0.73-3.76). Passive smoking (indirect smoking) ~ The husbands smoking status was available for 29 cases out of 37 cases and for

264 54 cases out of 74 controls. Before conducting the analysis a survey was made for 133 smoking men to study how many cigarettes were smoked daily at home. The result showed that none of the smokers of less than four cigarettes a day smoked at home. Since the purpose of our Study is to examine the effects of passive smoking at home, the smokers kho smoked at least five cigarettes a day were con- sidered as "smokers at home" in the present study. When the Tung cancer risk for non-smoking womeniwas observed according to the smoking habit of their husbands. The relative risk (,r.rj(M.H.odds ratio) was 2.25 (0.91-7.10) for non-smoking wives with smoking husbands compared to non-smo- king wives with non-smaking husband. Observation by number of cigarettes smoked per day revealed that r.r. for "less than 19 cigarettes"'was 1.16 (0.28-4.84)(Py 0.05) (cases 3, cont. lT), andRor "more than 20 cigarettes" 3.35 (1.17-9.67)(P ~ _..,~_..cds_.-._..~.....- --- ..~. .~ ., _ .., _ .. _ . «.-. . . . ._ _ 0.051){cases 15, cont. 19j,(chi-squan~.squan value for trend 4.06 P c 0.05~. The reiati- ie risk of lung cancer in women who themselves smoke was 4.25 (1.22-14.83) (P- ~ 0.059)(cases7, cont.7). {chi-square value for trend 5.46) (P<0.05). r When Stratffied by age groups the relative risk was 1.39 (0.29-4.91)' in non- smoking women with husbands smoking "less than 19 cigarettes a day". It was 3.16 (1.06-9.60) when husband5 smoked "more than 20 cigarettes a day". chi-square va- 'tue for trend being 3,90 (P< 0.05). r.r. (M.H.odds ratio),for "smoking women" ~ was 4.73 (1.22-15.35)(P< 0.05). The chi-square value for trend including smoking women was 5._48 (P<0.05). i . , When both age groups and districts were stratified, r.r. (M.HLodds ratio) was 2.58 (0:44,5.70) when husbands smoked "less than 19 cigarettes" and 3.09 (1.04- 1).81) when husbands smoked "20 or more cigarettes daily". The chirsquare value~ for trend was 4.25 (P<0.05)!. The relative risk for smoking women was 5.50 (11.06- 17?0). The chi-square value for trend including smoking women was 5.17 (PC0.A5). DISCUSSION A case-control study on passive smoking and lung cancer in women was conducted in two cities, distinctly different with regard to social environment. When both districts (social environment) and age group were stratified; relative risk of lung cancer in non-smoking wiives was shown to be 2.58 when husbands smoked "less than 19 cigarettes a day" and 3,09 when husbands smoked "20 or more cigarettes a day". The relative risk of active smoking (direct smoking) was 5.50 which was higher than the effect of passive smoking. Although study size is quite small,the present study might to considered to provide an another evidence favoring the pa- ssive smoking and lung cancer hypothesis. Saoking at home shuld therefore be re- stricted strictly in oder to prevent non-smoking family .Kmbers from suffering unnecessarily from lung cancer and other selected diseases. ,

l 285 Passive Smoking :Active Smoking Husbands None 5-19/d 20-/d' Smokiru . Smoking herse/f Nab i2 Chi-sousre for trend' --------------------------------------------------- eassive includins _ __ _ smokine activ~ smokinl _i ~ _»---___-__-__ Q crude 4-06 ~ 5.46 ~ ats strati _fied -~_~-~-----39p ------5.4.8 ----- tjf110 _~-4.20 5.17 ----- Fig., Relative Risk for Lung Cancer in Non-smoking Wives by Husbands Smoking Habit ~, A case-control study, Kamakura and Miura,) Kana[ava rrefecture, Jaoan REFERENCES 1. Hirayaena T(1981): Non-smoking wives of heavy smokers have a higher risk of Tung, cancer; a study from Japan. Br Med J. 282:183-185 2. Hirayama T(1984): Cancer mortality in non-smoking women with smoking husban- ds based on a large-scale cohort study in Japan. Prev Ned, 13: 680-690 3. Akiba A, Kato H, Blot WJ (1986)c Passive smoking and lung cancer among Japa- nese women. Cancer Res. 46: 4804-4807 4. Correa P. Pickle LW, Fontham E, Liln V, Heanzel Y(1983)~: Passive S.oking and lung cancer; Lancet, ii: 595-597 5. Trichopoulos D. Kalandidi A, sparros L (1983 ): Lung cancer and passive saiok- ing; conclusion of Greek study, Lancet, ii: 677-678 6. Pershagen G, Hrubec Z, Svensson C (1987): Passive smoking and lung cancer in Swedish woaten.AaI J Epideniol, 125: 17-24 7. Garfinkel L. Auerbach 0, Joupert L (1985) : Involuntary s.nking and lung un- cer, a case-control study;, J Natl cancer inst, 75: 463-469 -