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NOttel u ~+W.-*rw wl. IWict•d 4JI coprr iMr (T1W 17 U.3. 6 -lnvoluntary Smoking and Lung Cancer: A Case-Control Study' Lawrence Garfinkei, z Oscar Auerbach,' and Lou Joubert 2' ABSTRI4CT-In a case-control study in 4 hospitals from 1971 to 1981. 134 cases of lung cancer and 402 cases ot colon-rectum cancer (the controls); were identified; in nonsmoking women. All cases and controls were contirmed:by histologic review o1 slides, and nonsmoking status and exposures were verified by interview. Odds ratios (OR) increased with increasing number of cigarettes smoked by the husband. particularly, for cigarettes smoked at home. The OR for women whose husbands smoked 20 or more cigarettes at home was 2.11 (95% confidence limits: 1.13. 3.95). A logistic regression analysis showed a significant positive trend of. increasing risk with increased exposure to the husband's smoking at home. controlled for age. hospital, socioeconomic class. and year of diagnosis. Comparison of womeni classified by number of hours exposed a day to smoke in the last 5 years and in the last 25 years showed no increase in risk of lung cancer.-JNCI! 1985;, 75;463-469. Much interest has been expressed in the past several years in the reported relationship of involuntary or passive smoking and the development of lung cancer. Hirayama (1), in a prospective studti in Japan, reported: a 2:1 RR for nonsmoking women married to smokers as compared to the RR for nonsmokers married to non- smokers. Trichopoulous et al. (2), in a studv in Greece, found; that nonsmoking women with husbands who smoked had an OR about 2.5 times as high as that of women with husbands who never smoked, and the OR rose to 3.4 in women whose husbands smoked more than one pack of cigarettes a day. In another rase-controli studti. Coxrea et al. (3) found nonsmoking women married', to smokers.with a lifetime consumption of 41 or more pack years had an OR 3.5 times as highlas the OR of women married to nonsmokers. In an analysis of data from, the American Cancer Society's prospective study, Garfinkel' (4) found little if any increase in RR of lung cancer for nonsmoking women marrie&to smokers (4). The RR was 1.34 for light smokers and 1.10 for those whose husbands smoked 20 or more cigarettes a day. Kabat and Wynder (5) in a pilot study found no extra lung cancer risk in women and in nonsmoking men exposed to smoke at home,, but nonsmoking men exposed' at work showed a slight increase in risk. Kabat and Wynder measured exposure both by the spouse's smoking habit an& the subject's report of direct exposure. An investigation by Sandler et al. (6) of relatively young cancer cases in North Carolina found an overall. 1.6 OR (smokers and nonsmokers)r for exposed vs. nonexposed cancer cases. Exposed cases were those i,n which the husband smoked. Exposed nonsmokers had a higher OR than that of exposed smokers. In nonsmokers the OR were elevated and statistically significant for cancers of the cervix, breast, and endocrine glands. Occurrence of cancer in the latter two sites previously had not becn associated with cigarette smoking. Lung cancer also showed~ an elevated OR but was not statistically significant; however, the number of cases was small: Two papers in Hong Kong by Chan and; Fung (7) and by Koo et al. (8) show_very little difference between casesand, controls with respect to involuntary, smoking and; lung cancer. Except for the two prospective studies,, all of these studies were based on relatively, few lung cancer cases in female nonsmokers; the number of cases ranged from 22 to 77 in various case-control studies. In a previous paper, we pointed out that in any study of involuntary smoking and l'ung, cancer, categorizing nonsmokers by the smoking habit of the spouse may lead to error in classification of exposure. In the United States particularly,, there may be many women, married to nonsmokers, who are exposed; to the smoke of others at work or in other areas. Conversely, some individuals married to smokers may suffer acute effects from inhaling smoke and consciously avoid such exposure. A survey of; 38;000 subjects by Friedman et al. (9), confirmed this hypothesis. About 40% of women nonsmokers and 50% of men nonsmokers who were married to nonsmokers were exposed: to the smoke of others for some periods of time during a week, and 47°'~ of nonsmoking women marrie6 to smokers reported that they were not exposed to tobacco smoke at home. In the study reported here, we record the smoking habit of husbands (total No. of cigarettes smoked!and No. smoked at home), as well as the number of hours a day the subjects were exposed to the smoke of others at home, at work, and in other areas. Other causes for concern are establishment of the microscopic diagnosis of primary lung cancer and , A:aaRECIATIONS us[D: CL=eonfidencee limits;. OR=oddsratio(s); RR=reluive risk(s). . t Recsived April 22. 1985; accepted June 20, 1985 2Depanment of Epidemiologti and Stausucs, American Cancer Society. 4 West 35 St., New York, NY 10001. ~~ sVeterans Administration Medical Center, East Orange. NJ, and a~ C'niversity of Medicinc and Dentistry of New Jerary, New-ark. NJ C s 1R'e thank Dr. Robert V. P. Hutuer. St. Barnabas Hospttal, Lr% tng- ~ ston, NJ: Dr. Herbert Derman, Riverside Methodist Hospiul; Colum- W bus. OH: Dr. Jerry Rothenberg. Morristown Mrmonal Hospttal.CA Morristown, NJ;,and Dr. Douglas Smnh.,Middlesex General!Unrver-u siiti~, Hospital, New Brunswick, NJ, for granting us access to medtcal'I7'~~' records and pathologic mtertal. We also thank the (ollowrng,indtvtd- ual6 for making valuable suggrstions regarding the mnuscnpt Mr y s William Haensxei, Dr. E. Cuyier Hammond: Dr. Geoffre. Howe. Mr Edward Lew. Mr. Herbera Scidman. and Dr, Steven Stellman We also "~ thank Ms. Nancy La Verda and Mr Henn Vasquer for assistance in processing the data. 463 JKCL VOL 75. NO 5 SEPTEMBER' )985

464 Garflnkal, Auerbach, and Joub*rt verification of the smoking history. In a studyy of the histologic type of' lung, cancer in relation to asbestoss exposure, 49 of 774 men and women with a discharge diagnosis of microscopically proved lung cancer were recorded as nonsmokers in the hospital chart (10). After review of' hospital records, histologic sections, and interviews, only 10' cases remained who had~ died' of primary lung cancer and' who had never smoked! One- half of the others had smoked at some time and, one-half the confirmed nonsmokers had a primary cancer other than that of the lung. It is apparent, therefore, that more studies on in- voluntary smoking are needed, with particular attention given to obtaining microscopic proof of primary lung cancer and more detailed information about exposures to cigarette smoke. METHODS To have available enough subjects for a case-control study of involuntary smoking, we obtained access to the records of 4' hospitals-3 in New Jersey and I in Ohio. In each of these institutions, we identified all lung cancer cases in women recorded during 1971-81. In 2 hospitals the cases were selected from the Tumor Registry: in T hospital, they were selected from the surgical index in the pathology department: and in the other hospitals, records from the pathology laboratory were checked against the medical records diagnostic discharge index. No case was selected that had been diagnosed prior to 1971. Cases with cancer of the colon-rectum served as controls. Colon- rectum cancers have been shown in epidemiologic studies not to be related to cigarette smoking. Charts then were located and reviewed. Cases that were diagnosed clinically only or by cytology, or as sarcoma or lymphoma of; the lung, were excluded. Those that occurred in smokers (or ex-smokers), according to hospital records, also were set aside. Only those charts in which the patient was specified as a nonsmoker, or in which the smoking habit was not recorded, were further investigated: All the slides for these cases and controls were pulled~ from the files (an average of i15 slides/case) and were reviewed blind (by O. A.). In a small sample, slides for cases and controls were reviewed a second time to check consistency of the findings. Another sample of'slides for smokers with lung cancer, and for subjects with diagnoses of sites other than lung or colon-rectum, also were selected for histologic review and were mixed' in with the slides of nonsmokers. IC slides were missing or not available, or of too poor quality for accurate diagnosis, the blocks for the case were located, and new slides were prepared. An interview based on: a standard questionnaire was obtained for all cases and controls, along with micro- scopic proof. The interview was with the woman if she were still alive or with next of kin if she had died. Seven interviewers did all the questioning: three did interviewing in all 4 hospitals. About three-quarters of the interviews were with the patient or with spouse or children. Alli other informants had known the sub- ject for at least 25 years and were able to suppih the necessary information. All interviews were reviewed by the supervisor. When the information was incomplete, another respondent was contacted. A second interview was obtained in about 10~'0 of the cases and controls. Women who hadl never married! and', who lived with another member of the familyy were classified' according to: their relative's smoking habits. Therefore, the word "husband"' as used in this- paper means husband! or cohabitant living in the same household. Of the cases. 57% were married an& living with their husbands at the ume of the cancer diagnosis. The interview included questions on current smoking habits of the husbands of the cases and controls up to the present time or to the time of death; on the number of cigarettes smoked per day at home„and the number of years they had smoked. The interviewer also asked about the average number of hours a day the woman had been exposed to the smoke of others at any time during the past 5 years, during the past 25 years at home, while at work and in other areas, and during her childhood. Women whose husbands smoked cigarettes only occasionally were counted as not exposed: occasional exposure at home, work, or in other areas also was counted as not exposedi We matched l I'ung cancer case to 3 colbn-rectum cancer cases. Controls were matche& to within 5 years of age and were from the same hospital. In most age groups there were many colon-rectum cancers in~ women of the same ages for matching purposes. The colon-rectum cases were checked for histologic proof in the same way as were the lung cancer cases, and the smoking interviews were obtained by the same interviewers who obtained the lung cancer interviews. The interviewers were not told the diagnoses, nor did they know the hypothesis of the study. Several different analytic procedures were used: The Mantel-Haenszel procedure for obtaining a point estimate of the OR with a 1:3 match was employed,,as adapted by Pike and Morrow (11)„ with CL as shown by Miettinen (12); To compare subgroups of exposures„ the matching was broken, and OR and CL were computed by the Mantel-Haenszel method. In addition, a logistic regres- sion model was used, with estimation and testing procedures as given by Breslow and Day (13), To permit comparison with previous studies, the subjects' exposures to cigarette smoke were classified in several different ways: 1) exposure over the last 5 years, 2) exposure over the last 25 years, 3)' exposure to cigarettes smoked by husband, and 4) exposure to cigarettes smoked by husband at home. RESULTS Table 1 shows the process through which data for 134 cases of lung cancer in nonsmoking women were obtained from the four hospitals. Of T,175 women listed as having lung cancer, 892' (76%), were smokers or had smoked' in the pasr, according to hospital records. Of the 283 remaining women. 36 (1!2'.7%) were proved histologically to have other than lung, cancer upon JNCt. VOL 75. NO 3, SEPTEMBER 1985

Involuntary Smoking and Lung Cancer 465 TABLE 1.-Lung cancer in urrmen who nerer smoked. Records of 4' ltaapizaLs. 19; 1-81. No. of women examined Status At hospitals: l To ta % A B C D Microscopic proof of lung 243 93' 276 563 1.175 cancer on hospital record Smoker 200 70 182 440 892 Nonsmoker or smoking 43 23 94 123 283 100.0~ habits not stated° Reinterview revealed 15 3 41 54 113 39.9 smoker Reinterview revealed 18 14 45 57 134 47.3 nonsmoker No microscopic proof of 10 6 8 12 36 12.7 lung cancer ° 68%of the hospital records listed patient as nonsmoker; in 32%of the records, smoking habits were not stated. ret•iew of slides b, one of us tO. A_ J, and 113 (39.9 ro) were found to be smokers upon reinterview. OnI. 134 (47.3%) were lifetime nonsmokers with histologically , proved primary lung cancer~. They were the only cases therefore suitable for this study. Among the colon-rectum cases. there were marn fewer that were misdiagnosed-onl~ 1.4%. The age distribution of the cases and:controls is shown in table 2. 4lore than hall v:ere 70 vears of age or ol'der, and 22% were 80 years of age or older an the time of diagnosis. The histologic diagnosis of lung cancer cases was as foliows: 6.a b adenocarcinoma, 16% large celil, 8/10 squamous cell, 4% oat cell. 3% alveolar cell, 3% mixed, and 1% too undifferentiate& for classification b. cell t.• pe. Table 3 shows the OR and CL for risk of lung cancer, according to the 4 methods of classifying smoke exposure. The OR ranged'~ from~ 1.13 to 1.31. All 4 znethods resulte& in lower 95°'ro CL of less than I an&.were not statisticall., significant. Table 4 shows the average number of hours per day that cases and controls were exposed to other people's TABLE 2-Age diatribution of (ung cance* caFesand contTols Cases Controls Age, yr No. % N o % 40-49 5 3.7 17 4! 2 50-59: 28 20 ~9~ 86 21.4 60-69' 28 20j9: 88 21.9 70~ 79! 44 32:9 121 30.3 80-89! 24 17.9 82 20.4 >90 5 3':7 8 2.0~ Totall 134 100.0 402 100.0 TABLE 3.-OR Jor matcsled proupa of women for riak oJ'lung cancer from erpoaure to amoke: as claasiJied in 4 ' categories Classification Risk of lung cancer for women OR CL Exposed to smoke over last 5 yr 1.28 0.96-1.70 Exposed to smoke over last 25 yr 1.13 0.60-2:14 Husband smoked~ 1.22 0:97-1.71 Husband smoked' at home 1.31 0j94-1.83 smoke for the last 5 years and for the last 25 years. The women exposed during the last 5 years had an OR (adjusted for hr expose& per day ) of 1.28 (95% CL: 0.98', 1.66)~and those exposed for the last 25 years had an1OR of 1.12 tCL• 0.81„ 1.42). No increasing trend with increasing exposure was apparent in either group_ In the 5-year exposure group; the OR weno down with increased exposure, but the OR in each of the exposure groups .+•ass not statisticallv significant. Table 5 and text-figures 1 and 2 show' exposure classified br the husband's smoking habits. The OR for women married to smokers was 1.23' (CL: 0.94, 1.60); for those whose husband smoked at home it was 1.31 (CL: 0.99. 1.73). Komeri`whose husbands smoked 4Qor more I~, 9.50)E cigarettes: ?-da na OR of ` 199~(GT ~,j Women whose ti~3' or more cigarettes at homehad"atfORo~`2.'1 These were the only specific smoking groups in which the OR were statistically significant. The Mantel extension test for'" TABLE 4.-Ntim.brr of caeee and etratrolb exposed to smoke of others during 5 and 25 yr before diaQnoais Exposure. No, of hr/day Total f' No Variable None 1-2 3-6 _7 Total . o women ~ Last 5 yr 0 No. of cases 80 15 25 14 54 134: N No_ of controls OR 263 1.00 31 1.59 59 1.39 49 0.94 139 1.28' 402 CJ 95% CL 0:90-2.72' 0.96-2.03 0.69-1.28 0:98-1.66 Last 25 yr No. of cases 42 17 45 30 92 134 ~ Noo of cont l 3 72 109 85 266 402 ro s 1 6 ~ OR 00 1 0:77 34 1 1.14 1.12 95% CL . 0-60-0:99 . 0.96-1'.87 0.83r1.5T 0.81-1A2' ~ JNC VOL 75_ NO a, SEPTE>1BER~ iW

466 Garfinkel, Auerbsch, and Joub.rt TABLE 5.-Smoke rryoaure before lung cancer diagnosxa. aa claaaiJied by huaband'a sTtokinq hnbita Husband's total smoking habits Variable No. of cases No. of controls OR° 95% CL No. of cases No. of controls OR` 95% CL ° N Cigarettes/day Cigar and/ AlCtypes one <20 20-39 ?40 or pipe of smoking 43 148 1.00 11 45 0.84 32 102 1.08 30 52 1.99 18 55 1.13 91 254 1.23 0!61-1.16 0.81-1.44 1.13-3.50 0.78-1.62 0.94-1.60 Husband's smoking habits at home ° N Cigarettes/day Cigar and/ All'types one <10 10-19 _20 or pipe of smoking 44 29 17 26 18 90 157 90 56 44 55 245 1.00 1.15 1.08 2.11 1.17 1.31 0.84-1.58 0.76-1.54 1.13-3.95 0.80-1.70 0.99-L.73 ° Figures include single women living s]one. Cohabitants living with single womemwere classified as "husbands." °Mantel extension test for trend (one tailed): x= 2.31. P<.025. ' Mantel extension, test for trend (one tailed): z= 2:35, P<.025. ,&6I ~itz~l~iih~gioups was'~-statisticall-y' `significant (P<.025, one-tailed test), Analysis also was done for years of smoking. TCier~ ~rtifi2lht~ORvfor,t;those~smoking,fli ' ' '~0 29apeati! ' ae intal. snnokin~p.habiis -and 2 r7 for~ sinokintg af , u~no~ecid"was~"ap parelt~ Those who reported smoking for 30-39 years and 40 years or more had much lower OR that were not statistically significant. Table 6 shows OR for exposure categories by age group, histologic type of lung cancer, identity of the respondent who was interviewed, and socioeconomic status. Data are for average exposure for the last 5 years, for the last 25 years, by husband's total smoking habit, and by his smoking habits at home. OR generally were higher for those 70 years of age or over, for those with adenocarcinoma, when someone not in the immediate family was the respondent, and for those in the lower or lower middle class. There does not appear to be a pattern of' high OR for any of these subgroups in all 4 exposure categories. Some of the OR are statistically significant, but they usually carry very wide CL with them. r.:7 1.613 0 00 . 006 0 .orc <zo 20 ~o COYt•/ ALL =- i ^- ~_ .+-c aoKan G0+N+. . rF rJt3ES 43 11' 32 30 Is $F COlFT11pL1 IAa 46 KQ 52 I!B Z54 TExT-FICURE 1.-OR tor exposure to husband's total smoking habits. Total No. of women 134 402 Total No. of women 134 402 Table 7 shows the OR for classification of exposure of women to smoke at home, at work, and in other areas, as compared with those women not exposed at alL OR [or exposure at work during the last 5 years was 0;88;, for the last 25 years, it was 0.93. The highest OR observed was 1.77' for exposure during the last 5 years in "other areas." None of the RR shown in this table are statistically significant. One of the questions in the interview was with regard to exposure to smoke in childhood. Those women who replied that they had been exposed in childhood' had an RR of 0.91 (CL: 0.74, 1.12): LOGISTIC REGRESSION ANALYSIS An unconditional logistic regression model was used- which included terms for age, hospital, socioeconomic status, and year of d~iagnosis-to account for possible confounding factors. Testing was done on each of the four exposure variables, three of which were used in the Mantel-Haenszel analysi6: 1), exposure during the last 5 aii Gonw+.. a eq cI.lES44 29 17 . 26 ia toCO/fF#OI.S1S7 to, 59 44 . 55 245 TEXT.FIGU0.E 2:-4Rfor exposure to husband'ssmokrng habru athomc. io. \ 10-11 to. n (j°&R/. ALL .rE .OKtm JNCt. VOL. 75. NO S. SEPTEMBER 1985 202351261--9

Involuntary Smoking and Lung Cancer 467 TABLE 6:-OR Jo+ smake exposure cateyories, by age proup, histologic type of lung caneer, idtntitjt of respondrnt; and sociaeconomu statue Specification No. of cLSes Last 5 yr OR 95% CL OR 95% CL OR Smoke exposure Laat 25 yr Husband's smoking habits Age. yr Total At home 95% CL OR 95% CL <60 60-69 70-79 ?80 33 28 44 29 0.96 0.82 1.82 2.00 0.65-1.42 0:57,1.19 0.93-3.53 0.76-5.25 1.00 0.55 1.22 1.75 0:63-1.51 0.41-0.73 0.78-1.90 0:81-3,78 1.19 1.20 1.26 1.28 0.72-1.98 0.66-2.19 0.79-1.99 0.72-2.27 1_30 1.42 1.43 1.10 0.75-2.26 0.70-2:88 0.85-2:39 0.68-1.79 Histologic type Adenocarcinoma 87 1.43 0.99-2.06 1.15 0.85-1.56 1.33 0.94-1.87 1.48 1.01-2.17 Squamous cell carcinoma 11 1.28 0.52-3.19 0.85 0.43-1.69 5.00 1.28-19.33 5.00 1.43-20.18 Large cell carcinoma 21 0.55 0.41-0.74 0.67 0.47-0.94 0.76 0:51-1.13 0.62 0.45-0.86 Mixed and other 15 2.29 0.57-9.10 2.67 0.41-17.35 0.81 0:48-1.37 1.00 0.53-1.77 Respondent Self 16 1.96 0.62-6.17 0.91 0.51-1.60 0.83 0.50-1.38' 1.00 0j55-1.74 Husband 34 1.00 0.67-1.52 0.46 0.38-0:55 0.77 0.56-1.06 0.92 0!63-1,34 Daughter or son 48 0.92' 0.67-1.26 1.41 0.85-2.36 3.57 0.84-15.28 3.19 0.91-11.19 Other 36 2.23' 0.90-5.54 2.23 0.83-5.96 1.58 1.11-2.67 0.77 0:57-1.03 Socioeconomic status Upper and'upper middle class 6 1.60 0.31-8.19 1.50 0.34-6.59 1.23 0.36 -4.18 1.50 0.34-6.59 Middle clsss 75 0.78 0.63-0.97 0.92 0.71-1.19 1.15 0.84-1.59 1.21 0.87-1.69 Lower and lower middle class 53 2.58 1.10-6:01 1.45 0.86-2.44 1.23 0.83-1.84 1.45 0.88-2.38 years, 2) exposure during the lasr 25 years, 3) husband's smoking at home, and 4) husband's smoking outside the home. The latter variable was used rather than the husband's tota1 smoking as a check of the validity of exposure to husband's smoke and' was derived by sub- tracting the number of cigarettes smoked at home frorn the total number of cigarettes the husband smoked per day. Each of these factors was tested as a continuous exposure variable-the most powerful technique for detecting any true underlying risk. Table 8 shows the results of this analysis. Exposure for 5 years and 25 years had negative coefficients. The test for cigarettes smoked by husband at home showed a positive trend of increasing risk with increasing exposure and was statistically significant, with a P-value (one tailpd) of .032. The test for cigarettes smoked outside the home was not statistically significant. The table also shows esti- mates of RR at the 10 hours per day exposure level'and at 20 cigarettes per day smoked by the husband. The RR from exposure to 20 cigarettes/day smoked at home was 1.70; outside the home, it was 1.26: RR from exposure during the last 5 years and during the last 25 years were less than 1. A separate analysis that included respondent identity did not change the results materiallq,. TABLE 8.-LoQistu regression model' jor involuntary smoke exposure varsables, on continuous dose-response 6aeu TABLE 7.-NYmber of caees and crontrols exposed to urwke of others at home, at work, and in other areas Coefficient * Smoke RR' Smoke exposure Variable (SE) P-value exposure level Variable None At home At.rork In other areas S-yr exposure to -0.0069 0.422 10 hr 0.93 N smoke (0.0035) Q Last 5 yr 25-yr exposure to -0.016 0.303 10 hr 0.85 No. of cases N f l 80 262 37 99 14 52 13 24 smoke Cigarettes (0.031) 0.026 0.032 20 cigarettes 1.70 Cj o. o contro s OR 1.00 1.22 0.88 1.77 smoked at home (0.014) CA 95% CL 92 1 62 0 18 66-1 0 93-3 38 0 Cigarettes 0.012 0.127 20 cigarettes 1.26 ~ . . - . . . . m k d outside (0.010)) s o e r>a Last 25 yr home ~ No. of cases 42 73 34 19 ' Model includes terms for age. hospital. socioeconomic status: and W No. of controls 135 204 118 43 year of diagnoeis. Q OR 95% CL 1.00 1.15 0 89-1 49 0.93 0 73-1 18 1.42 0 89-2 26 ~ One tailed. . . . . . . ' Relative to the nonexposed woman. J'NCI. VOL. 75.,KO !. SEPTE4IBER 1985

468 Garfinkel, Auerbach, and Joubert D1ISCUSSIOM In a previous paper (4) the problem of classifving involuntar. smoking on the basis of the husband's smoking habit was discussed. It was pointed oun thar questions directed at ascertaining a quantitative estimate of the number of hours a day that subjects were exposed might be a better measure than the total number, of cigarettes that the husband smoked, inasmuch as not all of the husband"s smoking was done at home. In the present study we classified the exposure both ways: by the number of hours per day the subjects were exposed to smoke of others and by the husband's smoking habits. We also recorded the respondent's estimate of how many cigarettes a day the husband smoked at home. In this group of women, husbands who smoked cigarettes smoked an average of 27 cigarettes a day, of which 11.5 cigarettes on average (43%) were smoked at home. Of course, all cigarettes smoked at home were not necessarily smoke& in a room where the subject could have been exposed. In this study, the husband's smoking at home was related to the women's lung cancer, whereas number of hours of exposure a day, to all sources of tobaccosmoke was not related. A potential source of error was the hospital's report of whether the subject smoked or not. In this study, 40% of the women with lung cancer, classified as nonsmokers (or smoking not statedl:on the hospital record. were smokers at some time (table 1). Another 1310 did not have primary lung cancer. It is apparenr, therefore. thar in any study of' involuntary inhalation and Cung cancer, the smoking histories of the subjects have to be confirmed' as well as the extent of their involuntary exposures. Smoking histories of husbands were obtained'for the 113 women who were smokers. The distributioniby smoking habit is shown in table 9: As we might have expected, smokers are more likely to be married to smokers than are non- smokers. The table shows that 43 of 134 womem or 32:1%, of the cases included as never smoked in this stud-, had husbands who never smoked: buconly 21 of 113, or 18.6%, of' women who smoked and were mistakenl~ classified as nonsmokers in the hospi'tal record had husbands w ho did not smoke. Among the controls only 8,5% of women who were called nonsmokers (or smoking was not stated ) were smokers. The table shows the effect on the OR, when one assumes that 8.5% of the additional controls needed for the 1:3 match had' husbands with the same smoking distribution as the husbands of cases who were smokers, and that the balance had the same distribution as that of the 402'controls included in the study: The OR for the husband's smoking increase to 1.61 overall and are as high as 1.63 for the 20-39 cigarette a day, smokers and 2.32 for the women whose husbands smoked 40 or more cigarettes a day. For exposure to the husband's smoke at home, the OR are 1.66 overall, 1.53 for women whose husbands smoke 10-19 cigarettes a day, and 2.85 for those whose husbands smoke 20 or more a day at home. Thus the inclusion of women whose smoking habits have not been reviewed greatly, increases the OR. TABLE 9:-Hypothetica! OR resultinpJrom,eomD'inin9 women in study u-ith women originally classiJied as nansmokers bmt who actually smoked Husband's total smoking habits Variable Cigarettes;day Cigar All Totals None <20 20-39 >_40 and.~or pipe types of smoking No: of cases Nonsmokers (in study) Smokers (originally called nonsmokers) Total(unscreened) No. of controls Nonsmokers (in study) Additional controls° Total'(unscreened) OR 43 21 64 148 119 267 1.00 11 9 20 45 38 83 1.01 32 43 75 102 90; 192 1.63 30 24 54 52 45 97 2.32 1'8 1'6 34 55 47 102 1.39 91 92 183 254' 220 474 1.61, 134 113 247 402 339 741 Husband's smoking habits at home Cigarettes/day Cigar All Totals None andYor types of <10 10-19 >20 pipe smoking No~ of cases Nonsmokers (ln study) 44 29 17 26 18 90 134' Smokers (originally called nonsmokers) 23 22 22 30 16 90 113 Total'(unscreened) 67 51 39 56 34 180 247 No. of controls Nonsmokers (imstudy): 157 901 56 44 55 245 402 Additional controls° 126 75 52 39 47 213 339 Total (unscreened) 283 165 108 83 102 458 741 OR 1.00 1.31 1.53 2.85 1.41 1.66 ° Upon reinterview, 8.5%of the controls were found to be smokers. They weredistributed according to thesmokingdistribution of husbands of cases who were smokers. The balance were distributed according to the smoking habits of controls in the study. JNCL VOL. 75. -NO. 3. SEPTEMBER 1985.

Involuntary Smoking and Lung Cancer 469 > ) The classification used in this stud'} might be criticized because some women married to ex-smokers could be counted in the same exposure category as a woman exposed to smoke up to the time of her~final illness. However, all patients who have gone through diagnosis and treatment for lung cancer had some period oU time when they were not exposed to others' smoke, either before or after treatment. We believe that the classifica- tion we used was indicative of the "usual amount of smoke to which the person was exposed." To determine the experience of a"pure" nonexposed group,, 17 cases and 56 controls in this study were identified who were not exposed to the smoke of others during the last 5 years, during the last 25 years, whose husbands never smoked at home or elsewhere, and who never were exposed to smoke in their childhood. These cases and controls were compared with all other subjects. The OR was 1.14 (CL: 0.81, 1.59). In conclusion, we found an elevated risk of lung cancer, ranging from 13 to 3 1%, in women exposed to the smoke of others, although the increase was not statis- tically significant. The women who were married to smokers of 40 or more cigarettes a day or who were exposed to the smoke of~ at leasn 20 cigarettes a day at home showed a risk twice as high as that of women not exposed at all. This result is consistent with the d'ose- response risk of exposure to the hvsband's smoke shown in some case-control studies (2. 3). A dose-response relationship was confirmed in a logistic regression anah•sis. The lack of a relationship when exposure was classified by hours exposed to smoke of others may have occurred because this. variable does not accurately, mea- sure intensity of exposure. There is no consistently higher risk for: certain age groups or by histologic types, or by exposure au home or at work. Exposure in other areas carried a higher OR, but this finding is difficult to interpret. REFERENCES (1) HtRAi'AMA T. Non-smoking wives of heavv smokers have a high (2) (3) risk of lung cancer: A study from Japan. Br Med J 1981: 282:183-185.. TRICHOttOt'.Los D. KALANDIDI A,SRARRos L,.et al. Lungoncer and passive smoking lnt J Cancer 1981; 27:1-4. CoRREA P. FoN-rHAM E. PtcKLt CK';,et al. Passive smoking an& lung nncer. Lancet 1983. 2:595-597. (4,) GARrrNKEL L. Time trends in lung cancer morulitv among nonsmokers and a note on passive smoking. JNCI 1981!; 66. 1061-1066. (S) KABAT GC„ wrNDER EL. Lung cancer in nonsmokers. Cancer 1984; 53:1214-1221. 161. SANDLER DP, EvERSON RB, H'tLCOx AJ. Passive smoking in adult- hood and cancer risk. Am J. Epidemiol 1985; 121:37-48. (7) CHAN WC, Ft'r:G SC. Lung cancer in nonsmokers in.Hong Kong. In; Grundmann E. ed: Cancer campaign, Vol': 6: Cancer epidemtolog.. Stuttgart and New York: Fischer Verlag. 1982:. 199-202. (8) Koo LC. Ho JH•C. SAw D. Active and'passive smoking among female lung cancer patients and controls tn Hong Kong J Exp Clin Cancer Res 1983; 4:367-375. 191; FRIEDMan GD. PrTrtfi DB. Bkwot. RD: Pre+alence and correlates of passive smoking. Am~ J Public Health 1983: 73:401-405. 110/! AUERlACH O.,GARFINKEL L„PARkS VR., eu al. Histologic type of lung cancer and asbestos exposure. Cancer 1984; 54:3017-3021. (11) '. PIKE ,'tC., MORRON RH.. Statistical analysis of patient-controlstudies in epidemiolog.< Factor under, Investigation on all-or• none variable. Bt J Prec Soc Med 1970; 24:42-44 (12) MIET71!.EK OS Esumabiilts and estimation in, case-referenn studies. AmiJI Eptd'emtol 1976. 103.226-235. t13t BRESLOM NE.,D41 NE Stattstrcal methods in cancer research Vol 1. Analysis of case-control~studtes Lyoni IARC. 1980. J NCl. ~'OL 75 NQ 3. SEPTEMBER 1985'