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InterrHtlonal~JournaliofEpid.mioloyY vol. 20. No. t pintamational Epidemioloqinl Association 1991' Printedin Gtiat Brnai Smoking and Other Risk Factors for Lung Cancer in Xuanwei, China ZHIYUAN UU't, XINGZHOU' HE' AND ROBERT S CHAPMAN•' Liu Z hnatituta of Environmentsl'Hedth and Enyineerinp. Chinese Academy of Pnventive Medicine, 29 Nan Wei Rosd, Beijin910o5Q China), Hb X and Chapman R S. Smoking and other risk factors for lung cancer in Xuarnwi, Chins. Intsr- nationalJoumal olEpidemiologyi 1991; 20: 26-31. In Xuanwei County: Yunnsn Province, lung cancer mortality rates are among the highest in China in both males and females. Previous studies have shown a strong association of lung cancer mortality with indoor air pollution from 'smoky coal combustion. In the present case-control study, 110 newly-diagnosed lung cancer patients and 426 con- trols were matched with respect to age, sex, occupation (all subjects wera farmers), and village of'residence (which provided matching with respect to fuel use). This design allowed asseument of known and suspected lung cancer risk factors other than those mentioned above. Data from males and females were analysed byoonditionaf logistic reyres- sion. In females who do not smoke, the presence of Juny cancer was statistically significantly associatsd with chronic bronchitis (odds ratio [OR] I- 7.37, 85% confidence interval JCI]: 2.40-22.66) and family history of lung cancer (OR 4.18, 95% CI: 1.61-i0.85): Females' resutts also suggested an association of lung cancer with duration of cooking food (OR 1.00, 9.18 and 14.70)t but not with passive smokinp (OR 0.77.95% Cl: 0:30-1.96): In malh, lunp cancerwas significantly associated with chronic bronchitis (OR 7:32. B5% CI: 2.66-20.18). family history of lunp cancer 10R 3.78. 95% Cl: 1.70- 8.42), and personal history ofcookinp food lOR 3.36, 95% Cl: 1.27-8.88)i In malas a dose-response relationship oflunp - Mnesr withh smok'inp iadex (yaars of smokinp•smount of smoking) was slwwn,by risks of 1.00, 2.i1,, 2.17 end 4.70. i Examination of Chinese nationwide cancer mortality statistics reveals that lung cancer mortality rates in Xuanwei' County, Yunnan Province, are among the highest in China.' From 1973 through 1975, annualized male lung cancer death rates, age-adjusted to the 1964 China population, were 27.7 and 6.8 per 100000 in Xuanwei and China, respectively. Corresponding mortalities in females were 25.3 and 3.2 per 100000. Marked geographical variation in lung cancer mor- tality exists within Xuanwei. The county can be divided into high-, medium- and low-mortality areas, in which age-adjusted lung cancer mortalities in both sexes are 126.1, 20.9 and 6.0 per 100000, respectively. Xuanwei residents have traditionally burned three types of fuel, 'smoky' coal, 'smokeless' coal, and wood, for residential heating and cooking. Untib the 1980s fuel'. was nearly always burned in an open, unven- tilated fire pit in the floor of the dwelling's main room; 'tnstitute of Environmental Health and Engineering. 4ainesc Acadenry of Prevenwe Medicine. 29 Nan wei Ro.d. 8eijina t00030.. C7aiaa ••4A Eaviro.mennt Rvtectioe Aaesry. Rs.eatah Ttianale fhrl, NC 27711 tJSA. tPnasat address: Epidemiolagy firoup. Biolopeal and Medieal Raearch Diri.ion. Argonne National laboratoey, Bk3g. 2Q'I`1152. 9700 South Cne Aronue. Art onne. IL 60439 USA. such fire pits are still widely used, though the use of ventilated stoves is increasing. Women have generally been responsible for starting and tending the domestic fire and cooking food, though men assume these res- ponsibilities in some families. Tobacco smoking is very rare in Xuanwei women, yet women's lung cancer rates are comparable to men's. Also, a survey of past fuel use showed that in the high-, medium- and' low-mortality areas of Xuan- wei, the percentages of families using smoky coal before 1958 were 87.6%, 60.1% and 6.1% respect- ively. Corresponding perc:entages of families using wood were 1.4%, 19.9% and' 67.1"k. Indoor ooncon- trations of benzo(a)pyrene (BAP) averaged 627 ug/100 metres' (m) in the high-mortality area, and 46 ugl100 m' in the low-mortality area. In addition indoor pollution samples from the high-mortaliry area exhibited higher Ames-test mutagenidty than those from the lo.r-mortality area.' All of these obseF vations have served to suggest an association between indoor smoky mall burning and lung cancer in Xuanwei. Tbe case-canmol study repotted hero was designed to supplement existing information by assessing the influence of factors other than fuel type on the oaur rence of lung cancer in Xuanwei. Such factors, includ- 26 2423382SS9

Vol_ 20.No. 1i pr,nted in GrearBritain jfo r Vbn Wei Road, >i. China. lnter- oth males and' ,otlution from~ s and 426 con- fdence Iwhich ing cancer risk ogistic regres- d with chronic incer (OR 4.18, *ing food (OR is significantly 9596 p `. 1.70- onship of lung nand4.7o: 3., though the use of .men have generally ending the domestic n assume these res- n Xuanwei, women, -e comparable to use showed that inn ality areas of Xuan- using using smoky coal and 6.1% respect- s of families using. 1%. Indoor concen- (BAP) averaged -mortalitv area, and area. In addition high-mortality area genicity than those kll of these obser- .usociation between -id lung cancer in 9 here was designed on by assessing the :1 type on the occur- 5ucti facton, includ- RICK FACTORS FOR LL'NG CANCER Ih CHI%A ing tobacco smoking• family history of lung cancer. historv of'.chronic bronchiti's, and cooking habits, have been associated with lung cancer in areas other than huln.vei. but their importance as contributors to lung calt;,cr in Xuanwei has not yet been systematicallv dct,rmined. The present study also allowed comparir soli,,t the relative impact of these factors in males and' tom.JCs. %IATERIALS AND METHODS I~ )tuanwei. 93.4% of the total population were farm- zo in 1982: Because of this. and because lung cancer mortaltt-y in Xuanwei' farmers is high.' this study was confined to farmers. Concentrating the target popula- tion tended to increase the validity of the findings.' Betw•een November 1985 and December 1986, we identified 112 cases of newly-diagnosed lung cancer at. ,<uanwei hospitals and clinics. After exclusion of two patients with unknown addresses. 110 lung cancer pjtKnts (56 males and 54 females) were included in data analysis. Of these. 19 (17%) had been diagnosed on the basis of cytologicallpathological findings, and the remainder on the basis of clinical histories and ?i-ravs. Controls were selected to match lung cancer patients with respect to age (±2 years). sex- and'village of resi- dence. Because fuel use habits and dwelling types are ,imilar within individual Xuanwei villages, this design w-as expected to provide effective matching with res- pect to indoor fuel type and dwelling type. Such matching was sought because it would increase the effectiveness with which factors other than fuel tvpe could be assessed. Cases and controls were matched on village, with as many eligible controls included as possible. Therefore, we selected more con- trols for each case in a large village than in a small vil- late. The numbers of controls per case varied from one to five. After exclusion of 26 controls because of erro- neous questionnaire responses, 426 controls were includedIn data analysis, an average of 3.87 controls per case. There were 9 cases with I control, 15 cases r,ith 2 controls. 15 with 3 controls. 13 with 4 controls,, and 58 with 5 controls. A standardized questionnaire of the closed-question npe was developed. Study factors included tobacco use history. family and personal medical history, dom- estic fuel use history, indoor fuel use history, personal, history of cooking food, dwelling type, ethnic group linationality), and' socioeconomic and educational levels. After strict interviewer training and field' test- ing, this questionnaire was administered' directly to all lung cancer patients and controls. No interviewer or study subject knew the purpose of the study, and h>potheses. 27 A summary index of tobacco smoking was de%el- oped for each subject. The smoking index was calcu- lated'by multiplying the duration of smrrking (in vears) by the amount of tobacco smoked (in kilograms per month). A subject was considered to have a positive family history of lung cancer if atileast one relative was reporte& to have had the disease. The relatives included subjects' parents. siblings and'childrend and parents' siblings. A subject was considered to have a positive history of chronic bronchitis if he or she had been diagnosed by a doctor to:have this condition. or reported cough for at least three months per year for at least; two vears before the year of interview. A female subject was considered to have been exposed to passive smoking if there was at least one smoker (mainly hus- band) who lived in the same household. To assess the effects of individual independent vari• ables, unmatched, unadjustedvdds ratios (ORs) were calculated.`'Con6dence intervals were calculated'using Miettinen's method.° Dose-response relationships were examined for variables related to smokin¢ and cooking. Trends within these relationships were tested by extension of the Ivfantel-Haenszel procedure. To develop adjusted estimates of ORs associated with~ selected factors and' interactions. conditional logistic regression models were also constructed for males and females." Inthese models. all variables were dichotomous, assuming values of 0 or 1. The selected risk factors and interactions were treated as indepen- dent variables, and the presence or absence of lung cancer was treated as the dependent variable. These analyses were performed using the PECAN program.° "" RESULTS Distributions of characteristics in cases and controls are presented by gender in Table 1. Age, family size. ethnic group. birthplace, educational level. and dwell- ing type were comparable in cases and controls. so these factorswere not considered further in data analy- sis. The effect of active tobacco smoking was not eval- uated in females, since only one female (a control' subject) had ever smoked tobacco. The village match- ing provided effective matching on fuel type because fuel-use habits (type and average amount) were similar in cases and controls. Crude and adjusted ORs for smoking and cooking habits are presented with 95% confidence intervals for males in Table 2. No relationship between lung cancer and ever having smoked was observed. There was a suggestion of monotonic dose-response relationships of lung cancer with the age at which smoking began. duration of smoking and amount smoked ~ b-v month.

Average age (years) No~ of peopk in family now No: of people in tunily 20 yeus- ago Plan nationality (~%) Born,in Xuanwei (%) 7rro-uorey dwelling (%) Aooum d'.aoky ood tNnnt (toos/year) Anount d wood twnt (101111year) However, none of these relationships was gtati: C7,o.. IASS /9b6 fignificant.Jm mUtrast. a statisttically signi5cant Maks Females ca.a Caotrob Cases controh 52 s0 32 32 5.6 5.4 5.6 5:4 5.8 5.5 5.9 5.5 94.6 96.9 98.2 97.0 100 100 100 96.0 98.2 99.1 100 100 response relationship of lung cancer with smo index was obaerved. The adjusted OR in men often cooked food (at least once a day) was 3.36 (95 CI: 1.27-8.88). The adjusted ORs were slightly than the crude ORs. Crude and adjusted ORs for cooking and passiv smoking are presented for females in Table 3. No dose response relationship of lung cancer with age at whi the woman began to cook food was observed, but the OR associated with the age arwhich the woman beto to cook food (11-15 years old) was signiflcant, Adjusted ORs assodated with the duration of cooking .veremueh larger than crude ORs. There was a sugges. 4.2 4.2 4.0 4.1 tion of dose-response relationship of lung cancer with o.a 0.9 0.8 1.0 the duration of cooking food for the adjusted ORs. No TAns 2 Orfb i.oou (OR) od 9J % cnffAdewor 6trrv.Ib (CI! Ja h+V QOrll Y1/1Yltl apeolldOlj pJUqOb/ta MQ ODAkLIj.. XU-MYJ, CAYtO, lABS-1996 Factor Ever-smoker No Yes Aac of wrting to smolu (years) Never >20 rso t}end (p value) Cases Controls O1ie• ORa•• 95% Q 4 19 1.00 1.00 52 205 1.20 1.26 0.30- 5.26 4 19 1.0D 1.00 2o e0 1.19 1.10 0.25- 4.93 32 125 1.22 1.39 0.32- 6.06 (r-0•m) Yean of smoking 0 -K35 2035 71sad (p .atue) Amounrd smoking (IWper mootII) Ne.a 490.5 0.6-1.0 >1.0 Tlend (p..fie) mdal Smoking Q 2- 20- 33- 1M.ad (p.alue) OAn mok" bod lio ... Ys . .. 4 19 1.00 1.00 30 146 0.9E 1.07 0.25- 4.39 22 59 1.77 1.71 0.36- a.12 (p>0.05) 4 19 1.OQ 1.00 25 93 1.29 1.41 0.33- 6.09 20 93 1.02 1.09 0.74_ 4.a2 7 19 1.73 1.91 G-12-11.40 (P>0•05) relationship of lung cancer with passive smoking was observed. Odds ratios for family history of lung cancer and per- sotlal history, of chronic bronchitis were signi6canti'y associated with lung cancer in both sexes but duration of using an unventilated fire pit was not (Table 4). All conditional logistic regression ORs were larger than crude ORs in Table 4. DISCUSSION This study was intended to supplement previous stud- ies which had shown a strong association of indoor smoky coal combustion with lung cancer in Xtunwei County.l1 Full understanding of lung cancer aetiology in Xuanwei, and comprehensive risk assessment of the effect of smoky coal use, require systematic assessment TAau 3 0416 Raio. (OR) wd 95% aayideeor itrssrb (Cl) /or irq oim i. A-a .morsliks .o ooabry a.1'p..- + awo'da6, X+rwrq CAw., 1M-1966 Ap datarting Io coot >15 13 11-15 30 4610 11 4 30 1.00 1.00 'ILad (y.alas) 24 - 94 1.a2 2.61 0.69- 9.a2 Ye.n d mWH.a 16 74 1.62 2.17 0.35- 8.64 430 7 12 21 4.28 4.70 1.0:-21.40 31-44 28 0.0•CI) >43 19 'B.ad (P.alae) M 200 t.00 1.00 ra.f`l mokhg 12 24 21? 3.36 117- t.p No . . f. '0Re ~ Oude odb r.tfw. Molta - ordt ratio arer adlammeat by m.dim.al 4tmle eepa.eioe lo[ etlv Tit t.not. s.o*ng ioda - Y.aa of Smattq'A.ovrd aeati.t. tNTERNA71ONAt JOURNAL OF ET07EAQOt.OGY Yr LS

ships was statisriaay callyy significant rr..,_ cer with smo_"a!. ~ncerted~ OR in men ~o - day) was 3.36 (95q, VCrC slightly larget cooking and pasi :s in Table 3. No doselcer with age at wtvch .vas observed', but tbe iich the woman be, , Ad) was signif;cant„ .e d'uration of cooluag s. There was a sugga- ip of lung cancer With the adjusted ORs. Na passive smoking .(,. if lung cancer and per~ itis were signiS¢antly nh sexes but duratioa was not (Table 4). ,w )Rs were llarger t}an lement previous stud. sssociation of indoor lg cancer in Xuan" iung cancer aethllogy risk assessment of the ystematic assessment i RICK FACTORS FOR LUNG CANCER IN'CHINA 29 Qodds r y,io., ( pR) and 95% confidence inMervais (CI) for luna eoncer in males and females. according to familial hrsron of lung 1~ ~Adluo tnncer, history of chronic bronchitis and years using un.mrrloted fire pit. kuanwti. China. (9Bt-/AA6 Males Females Total F.CO Case Control ORa' (95% Cl) Case Control ORa (95% CI) Casc Control ORa (95°-o Cl). / iandw~ n w~t d ~~ .ncc 41 200 45 192 86 ?92 ' %o 15 24 3.79 (1.70- 8.42) 9 10 4.18 (1i61-10;85) 24 34 3.75 (2:03- 6 .83). N~H~ romc 39 209 38 194 Tt 393 w 17 13 7.32 (266-20.18) 16 18 7,37 (2.40-22.66) 33 33 7.61'(3.62-16;Op) Ya rite pt 22 107 21 84 43 191, 645 31 117 1.78 (0.4(r 6.93) 33 118 0.73'(0.20- 2.60) 67 235 1.12 (0 ,4(-- 2.74) ~ aner ad)assment by aonditional lopstic rejrcuion for other risk taaort:•. oRa' ~~ o{ {uel use,. but of other known and suspected ii flMIs as well. To achieve such an assessment, we d9" a study' desi8n' which provided effective case- conuol matching with respect to fuel type and average ancwnt ased as well as to age and gender. X,MM,,i n a very rural area. In the present study, ,tmostall lung cancer patients were diagnosed by the n ~pita(s. Only 17% of the lung cancer cases ~ brsed on cytological/pathological findings, 83% „,.n based on clinical histories and X-ray findings. Tberefore. misclassification of the cases may exist in *e ttydy; H,owever, other reasons may itnprove valid- lm n( wng cancer diagnosis in the study. Because of E7 l, care in Xuanwei, most lung cancer eachcd an advanced stage of the disease diagnosed, and local doctors had wide experi- eeec of this diagnosis because of the high lung cancer .orbidity in Xuanwei : In order to assess validity of the di%poi we also followed up a number of lung cancer p.uentsfrom the study, almost all of whom died within a .oo16s of diagnosis. ls both males and females, the current study d'u- do.ed oonsistent and statistically significant asssoci- anm of lung cancer with chronic bronchitis and poi f.mily historyof lung cancer. Lung cancer was ab as>;odated with the frequency of cooking food (in .des) and the duration of cooking food (in females), e.es after the matching on fuel type inherent in the +4df design. Not surprisingly, lung cancer was associ- ned.ritb active smoking in males. No association with IIOrK anoking.vas observed in females. !a XuaaNei, women are generally responsible for maki.g food. so the variable 'cooks or does not cook fDOd' muld not be assessed in females. However, the 004 rooated with the variable 'years of oookiag' suggested that lung cancer risk inaeased with increase in duration of cooking (Table 3). There was no dose- response relationship between lung cancer and age at which a woman began to cook food. This observation may be due to the possibility that women who reponed cooking food at less than ten years old did not really cook food at that age. The OR in males who often cooked food was over, three times greater than in those who did not. DCis likely that those who cook food inhale more coal-smoke pollution than those who do not. Wu er al reported that subjects exposed to burning coal used for heating or cooking in a stove or fireplace during the majority of childhood and the teenage years had a lung cancer risk 2.3 times higher than subjects who were not so exposed."' Wang er al have reported similar results from China.12 Gao er al reported increased risk of lung cancer in Shanghai women who cook frequently with rapeseed oil.11 This observationn raises the question of whether pollutants associated not only with the cooking fuel!but also with the cooking method promote lung cancer. The observed association of lung cancer with posi- tive family history of the illness may be attributable in part to recall bias. However, our results are consistent with other studies"" which tends to reinforce the validity of the association. Our relative risk estimates for positive family history of lung cancer. 3.79 in males and 4.18 in females, were also similar to previous stud- ies. The association may be due partly to the fact that a subject's relatives lived in the same environment as the subject for some time. Mulvihill has postulated that some abnormaltypes of gene mightincrease sensitivity to environmental carcinogens." Further research will be necessary to elucidate and distinguish the roles of genetic and environmental factors in carcinogenesis.

30 iNTERNA7IONAL JOU1W AL OF F2>mPaUOLOOY Tobacco smoking is generally accepted to be a major cause of lung cancer""2 We observed an association of lung cancer with tobacco smoking in males, and this observation tended to enhance confidence in the results. However, the association was weaker than has been reported in many previous studics. "' When con- sidered individually, duration of smoking, amount of smoking, and age at which smoking began were only weakly associated with the illness. Only the smoking index derived by multiplying duration by amount of smoking was significantly associated with lung cancer. These observations may be due partly to the fact that only 23 (8.2°k) of 280 males in this study were lifetime non-smokers. In such a small comparison group, even fairly small changes in the distribution of non-smokers between ce ses and controls could have produced marked' diBerences in observed ORs associated with smoking. More importantly many farmers in Xuanwei smoke tobacco through a long bamboo cylinder partly filled with water and'the passage of smoke through the water may filter out carcinogenic substances. Studies comparing the composition of water-filtered to unfil- tered tobacco smoke are currently in progress. It is also quite conceivable that the large amount of air pollutants inhaled' during indoor smoky coal burn- ing in Xuanwei partly overwhelln the ar+ciaogenit?. effect of tobacco stnokint For example, as mentioned above, the average indoor concentration of BAF in the Xuanwei region of high lung cancer mortality was 627 ug/100 m' in a recent survey: An individual inhal- ing 12 m' of air per day might therefore inhale 9154 ug of BAP in a year if be or she spent eight hours per day indoors. In contrast, an individual smoking 20 cigaret- tes per day might be expected to inhale only about 700 ug of BAP in one year.n Thus, it is not especially surpnsing that the ORs associated with smoking in Xuanwei males were smaller than reported in other studies. Because unusual environmental conditions prevail in Xuanwei, it would not be advisable to generalize these ORs to other areas. Smoking is very rare in Xuanwei' females. In addi- tion, we observed no association of lung cancer with passive smoking in females. Such an aauadation has been reported in several previous investigatioos."s'' in non-smoking women in Shanghai, Gao st d ob.erved a limited association of lung cancer with passive amolc- ing, in tbatstudy the relative risk ranged Erom L0 in womea living leaa than 20 years with a smoking mua- band to• 1.7 in those living with a smoking husband for at 1wt .40 yeas." However R,oo a at have: sot ob.etved' a consistent association of lung cancer with passive awking in C3inese.vomen'"° Tbeae aotboas also stated that correlates of passive :moldnt aticb .a diet and socioeconomic status can act as ' confounders when the health risks of passive are evaluated." TThe beavy indoor air pollution ` Xuanwei may also overwbelm~the carrdnogenic eff, of passive smolciaot The effect ©f passive smok1nZ 4 tung caltcer may depend' on local environmental ~ tors and results obtained in a given region may ther, fore not be applicable to other regions. In summary, this study was undertaken to sup plement existing evidence showing a strong associatiay of lung cancer with indoor use of smoky coal in XuA& wei. Our results disclose important associations of luer< cancer with factors other than fuel type and therefoh indicate that these factors must be considered in " comprehensive, quantitative risk assessmet.: of lun; cancer in Xuanwei. Our results also confirm imdircalj, that smoky coal pollution is an iinportantdeterminant of lung cancer in Xuanwei. A separate case-contrM study, which will allow simultaneous direct analysis of the effects of indoor air pollution and other known and suspected lung cancer risk factors in Xuanwei, : currently in progress. ACIINOWLEDGEMEN'1"S The authors are grateful to Chaofu Huang and Deyi Shan, who helped with data collection. REFERENCES , ' Omoe d reacarcr of a.eowr preventioo and trntment. Mi.istr+y of Health: !?um of awen mw.aliry U dr Poopk'a Repmb/ir of crw., Bc*&,19eo. ' Mt®foed 1 L, He X x, Cbape.a R S..r.L Luna nxar ad iodoor air poUutioe i6 Xuaesi, Cbifoa. Sdenu 1997, Z13: 217-20. ' Oapman R S, Mwnford J L, Flarru D B a.7: ibe epdemiolog of luog aeoer in Xuanwsi, Cua: Qoreat proQes. irna, .nd esseacR ftrHepa. ArcA Earirum flwfal 1968, x 1W-s. •SaeleoNm.n 11. C.us+owoor,edio: noijn c.owe+.cr .Rn.rJa:.. Ncw Yat. Orlmd U4iwetiqr Rnes, 19d2. ' 1alieatcld A M. Lliaateld D. Powd.ewu of epidonioJoB. New York. Odoed Umveiairy rerat, Secvod. 1980. ' M'sestmen O S. fsdm.biNtytnd'cdmsooe m o.e-n;ferent atdes. Ani ! Epsendol 197b: »x 226-95. ' Maatd N. Cai aquare eatt with one deQw of Seedom: eitanoon d tYe M.aoN-}iaemd peowbsre. J' Am Sr Aaaoc 1963: !! 6AO-70o: ' Bs.bw N E, D.y N E. SaiUoei.f..erAcdr N owca neno,cA, Vot J, 77w w.fjeb of nrs-cvospl xml:a L"s, IARC Sontisr t.biiealo. No }3, t9MO. '(3.l Y H, Loein J H, Robiewein L V. L'J<si'bod o1uluioea for eached or.nend .qtdm and wrt+i.al wma.itL wd death times. Aiowroik. 1991; it: 7Q'!-1 • Sooiv B E, Mae6oider S, Btedow N E.1Ldmom ikeLaood fttkftj d aeaeal twWk .o" ntQ.efsrd dw. Ap# Srder 1993, 32: gT2-t1. " w. A H, HesdB& TSks Y C,1f. H C. yeoking rd oria oik hcYonax ImB aeost ie vromsa. lNCl19BS: 7k 747.51. • w.y X Z Lrq aeeer a.d .k poUasio. isdoor ..d o.udour. E+rkaw.at wf 1icaAY 1993; 1='7-12. ' ' ' -` •&s Y'L, Biot w 3, neq w;,.r d;,oa e.~ a.ong Chi.rs .. .a.a heJ Q'wai. UP. 46 601-4. •i 1 . 1 rMiP so u 3'L aT

RICK FACTORS FOR LUSO CANCER lv CHINA -Higginwn J, Jenrnn 0 M. EPldemiologiotl rt.ikw oLliun{ cancer in man. Inc Mahr E. Scfiwaalil D. Tomatis L(ads). Air pulh+ticw. wrd cancer in nwn. Lyon. It+iRC. 1977. Tukuhutr 0 K. Lilientctd A M. Familial ujgrcZation of lung cancer in human. JNC7 1963: J6t 289-312. (h+i W'L. Elaton R C. Chen V W,' Saile,v-Wihon J E. Rothechild H. Increased famili.I ri.k forlung caneef. JNCI 1986; 76r217-21. 'Cx>ffman T E. Has.in;" 0 D. Mulvihill'J J. FamiGal'respiratory tract pexer. JA:,(A 1982:317: I(12f1-J. `' Mulvihill J). Hottl.ctort in human IunR turnourt an example of eco- Eenetka in onco:ogy: JNCI l976i 53: 3-7, Lue6 L A. Errntsr V L. Warner K fi, Ahbotts7, Gs3i1o J. bmoking and lung anmr: an overvkv+: Cancer Ra 1934; (12. pt T): !9w-sa. Wynder E L. Gratiam E A. Tob.eco smokin{ aa a poesible etiolog- te2l factor in bronehutenie arcinoma. J.LSfA 195C1: 1'13t 329-36. ticvin M L. C+oldltein H. Gerhardt P R. Caneer and tobaeto wnok+ Ing: PtCliminary roport. JAMA 19711; 143: 136-8. =potl R, Hill A B. Smokinj and carcinonu of tbeluttj: h'eliminary nport. er Mea/ J 1950: 3r 734-e8. ' W HO: lieohA h.zarda of rh'e Muwtan mtvironnteet. C eoeva. 1972. oTrichopoulos D. Kalandldl A. Sparrros L, MacMihon B. Lung cancer and paui• e eRwklh{.1nN Gncer 1961; 27t 1j: I I i i 31 ~ Correa P. Pickk L W. Funtham E. Lin Y, H:kntscl IW: Paaslvr itnok• in4 and lung csntet. Tht Larcet 19+t3: lts SyJ-7. a'GarRnkol L. Passive smokin4 :utd ecu+ccr-Amenun eapenence. Prov Med 191i4: I3: tA i-7. ~ Blot W J. Fraumeni J1F Jr. Passuve smoking and lung cancer. J'NC1 t511t6: rn 993-ttllxl; ~ Ktxt L C. H'n J H-C. Saw D. Anive and pantve wwkfnp aftang fomile lung canecr Patients and euntn+b in HunY Kong. J£ip CYi. Cancer Ra 19113: it 367-73. r Kau L C. Hu J H-C, $aw D, It pwive smolinE xn addMd ruk taetor for lune caneor in Chtneu women? J Eap C7in Cancer Rea 1986t J: 277-~{3. ' Kou L C. Ho J H-C. Saw D. Hn C-Y. NIeaaurcment of' pu+ive sntokinE and enimatcs o{ tisk for Ikn4 ancsr among non. smokins Chinese females. Jar J Cunerr 19ti7:19: 162-7. " Koo L C. Ho J H{. Rytander R. Life•hietory eorrelatce of environ- mentat tobacco emoke: A study un numenoklhg Hong Mwng t7iinete wivn with unoklnf versus nonsmoking husbands. Soe $d Med 79dp: 2603 1-t1. (;Reviued verrion received Septrnfber 1940), i