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. ~ 1988 Elsevier Science Publishers B'.V: (Biomedical D v,sionl Smoking and health, 1987. yl. Aoki ec al, editors PASSIVE SMOKING AND LUNG CANCER IN WOMEN REIKO INOUE, TAKESHI HIRAYAMA• Kanagawa Cancer Center, Asahi-ku, Yokohama 241, Japan Institute of Preventive Oncology. Shinjuku-ku, Tokyou 162, Japan• INTRODUCTION A case-control study on smoking and lung cancer was conducted im 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 cancer. 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 women, 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. Epidemiologicalistudies thus for reported since 1981 mostly suggest such possibi- lilty (1i-7)1. Therefore the role of passive smoking on lung cancer in women was ex- amined inithe present case-control study. MATERIALS AND METHODS Husbands smoking habit of 37 cases of women died of lung, cancer in Kamakura and Miiura (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 (~ 2.5 years),and the district. Cerebrovascular disease cases were seiected as cont- rols because the disease is known to be related'neither to active nor to passive smoking. Interviews were conducted by trained local public health nurses and mid- wives using standard questionnaires.ttantel-Haenszelodds ratio was calculated for reliative risk (r.r.) with 90% confidential intervals. RESULTS Active smoking (direct smoking) 24.3% of wcenen smoked ini case group (smokers 9, non-sAnkers 28), and 16.2% smo- ked in control group (smokers 12. non-smokers 62), relative risk (r.r.)(M.H.odds ratio)ibeing 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 N

284 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 lung cancer risk for non-smoking women was observed according to the smoking habit of their husbands. The relative risk (r.r.)'(M.H.odds ratio),was 2.25 (0.91-7.10) for non-smoking wives withismoking husbands compared to non-smo- king wives with non-smoking 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)(P> 0.05) ~„cases 3, cont. 11)1, and~for "more than 20 ciyarettes" 3.35 (1.17-9.67)(P• r r. .., __.. • ...-. .. .. 0.051)tcases 15, cont. 19),(chi-square value for trend 4.06 P< 0.05). The reliati- rve risk of lung cancer in women who themselves smoke was 4.25 (1.22-14.83) (P• 0.059Y(cases7, cont.7). {chi-square value for trend 5.46) (P<0.05). ~ When stratifiediby 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 3.1F (1.06-9.60) when husbands smoked "more than 20 cigarettes a day",,, chi-square va- lue for trend being 3'.90 (P< 0.05). r.r. (M.H.odtls ratio) for "imoking"`v;omen" was 4.73 (1.22-15.35)(P< 0.05). The chi-square vaiue for trend•including smoking wom.en was 5.48 (P<0,05). When both age groups and districts were stratified, r.r. (M.H.odds ratio) was 2.58'(0.44-5.70) when husbands smoked "less than 19 cigarettes" and 3.09 (1.040 ¢a11.81) when dasbands smoked "20 or more cigarettes daily". The chif-square'vaiue for trend was 4,*25 (P(0.05). The relative risk for smoking women~,w,s RSOt(].09- 17.30). The chi-square value for trend including smoking women was 5.17 (PC0.05). DISCUSSION A case-control study on passive srtaking 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 wives was shown to be 2.58 when husbands smoked "less than 19 cigarettes a day"' and 3.b9 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. 5moking at home shuld therefore be re- stricted strictly in oder to prevent non-smoking family menbers from suffering unnecessarily from lung cancer and other selected diseases. .

285 Ch1-souare for trend ---------------------------------------------------- _ oaasivt includin[ _ __ smokine_ ~Ctl~e smakine ~-----°---__---- -_ rude c a-O6 5.46 --- ---------- -- ~ - ---- ----- asc stratified -3.90 5.4.8 _ 5~1-_ast_diatricf_strat-fied a•20 _.____S. 17-_---- Fig. Relative Risk for Lung Cancer in Non.smokimg Wives by Husbands Smoking Habi2 ~ A cast-control study, Kamakurs and M1ura.a Kana[awa aref.cturto Jaoan REFERENCES 1. Hirayama T(1981): Non-smoking wives of heavy smokers have a higher risk of lung cancer; a study fromiJapan. 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. Prey Ned, 13: 680-690 3. Akiba A, Kato H, Blot WJI(1986): Passive smoking and lung cancer among Japa- nese women. Cancer Res. 46: 4804-4807 4. Correa P, Pickle LW. Fontham E, Lin Y, Heanzel W (1983) : Passive Smoking and'lung cancer; Lancet. iir 595-597 5. Trichopoulos 0. Kalandidi A, sparros L (1983 ): Lung cancer and'passive smok- ing; conclusion of Greek study, Lancet, ii: 677-678' 6. Persfiagen,G, Hrubec Z. Svensson C(1987): Passive smoking and lung cancer in Swedish women. Am J Epide>w+iol, 125: 17-24 7. Garfinkel L, Auerbach 0. Joupert L(1985) : Involuntary smoking and lung un- cer, a case-control study; J Nat1 cancer inst, 75: 463-469