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FILE NAME State of the Art Literature SAL DATE 1954 DOC SAL058 DOCUMENT DESCRIPTION Journal Article - Occupations and Cigarette Smoking as Factors in Lung Cancer  wetenan NAD Me nsmned tang.camsvires Aeneas anime ear areas eS Eig eg ge ore Sires Bije Sa ons: y oa eS Si ST te BS bores " t 2 at erate OFS ne EOS eab een Ss er t. Baty ree aeeas Soar RSs Die, 2s . So a te arte SE Ww Occupations and Cigarette Smoking as Factors in Lung Cancer LESTER BRESLOW M.D. F.A.P.H.A. LeMAR HOAGLIN GLADYS RASMUSSEN and HERBERT K. ABRAMS M.D. F.A.P.H.A. This four study offers additional evidence tending to connect kenzy cigarette smoking with cenerr. In addition it lists several occupations that seem to have some etiological relationship to the disruse They need further study as it is suggested studies have implicated cigarette smok- ing 28 and certain occupat*io- ness- pecially those involving exposure to radioactive and chromate ores and asbestos the causation of lung cancer However the number of per sons known to have such occupational exposures in the United States is rela- tively small The Thesharp increase in lung cancer ruurtality constitutes one of the most tacular disease phenomena of the past two decades In the United States the adjusted mortality rate for lung janeer elinibed from 2.7 per 100,000 pulation in 1930 to 11.0 in 1948 a ore than fourfold increase In at least The present investigation was under taken four years ago 1 to determine whether any additional occupations might be involved in lung cancer and thus deserve intensive investigation and 2 to obtain data on the role of tobacco usage in lung cancer ne state California pulmonary cancer Low arcounts for more deaths than does julmonary tuberculosis and among males aged 45 6i4t causes 4 per cent of all death~-r Attempts to explain this rising mortality as spurious e.g. as due to im- pewed diagnosis of the disease do not stand up The lung cancer death rate- which unfortunately is still our best - pproximationpproximation of incidence rathe as increased two and a half times more rapidly among men than among women the can hardly presume that physicians ve applied diagnostic improvements ~~ uch more completely to mien than + wonen Likewise the increasing projettion of lung cancer found as a cause of death among autopsies supports the cotalusion that we are dealing with a al increase in the disease Environmental changes appear to fer the best explanation appear the plcnomenon Previously published Methodological Considerations Definitive study of whether an occupation or cigarette smoking is a causa tive factor in lung cancer requires that the incidence rate for the exposed group be determined This rate is then com- pared with that of a control population the most acceptable control being all the rest of the population from which the Dr. Breslow is chief Bureau of Chronic Diseases California State Department of Pub lic Health Berkeley Calif and Mr. Hoaglin and Mrs. Rasmussen are also associated with this department Dr. Abrams who was formerly chief Bureau of Adult Health California State Department of Public Health is now medical director Health and Welfare Fund Chicago Office Theater and Amusement Building Janitors Union Local 25 Chicago IIL This paper is based on a study supported by a research grant CS 9047 from the Na- tional Cancer Institute PHS and was pre- sented before the Industrial Hygiene Sretion Health of the American Public Association at the Eighty Annual Meeting in New York Y. November 10 1953 171 AES Sat SEES. pe baa ly Ae setae > ; 1 wees sm ae a dare 8-28 Arty ' ge nn TNE a ackeh RSac AOOPD E pe eNI eLeO neEe EatotRie ayOMIA ah MR Tee ee Naa < aria onteds Bwset iste ya EVs Regen penine =| ll oe a De er e- ef te rane cote fe : 172 FEB 1934 AMERICAN JOURNAL OF PUBLIC HEALTH exposed group came Assuming the note the frequency of the various occu- same diagnostic and reporting standards for both groups one may thus deter- pations on death certificates where the disease appears as the cause of death ; mine how the chance that a member of The frequencies of the occupations on an exposed group will develop lung such death certificates may then be com- ' cancer compares with the chance that pared with those on all death certificates such a person would develop the dis- for the general population If certain case if he were not a member of the occupations appear with much greater exposed group If the likelihood of developing lung cancer is substantially in- frequency on death certificates for lung cancer than on certificates where death creased by being in the exposed group is due to other causes one may conclude e.g. a certain occupation one may that the occupation may be involved conclude that the exposure is a causative factor in the disease The key to this and should be intensively investigated Important achievements may be credited analysis lies in determining comparative incidence rates for a suspect group and a control population But first it is necessary to identify suspect exposed groups That was the aim of the present study The importance of pin pointing these groups arises from the fact that incidence to the use of this method However major difficulties with this use of death certificate data arise from the following circumstances only one occupation may be recorded while this is supposed to be the usual occupation it is often not correctly recorded and duration in the occupation is not recorded All these studies require assembling sizable popu- circunstances tend to blur the identifi- lations and observing the occurrence of cation of suspect occupations from death the disease in them large and ex- certificates pensive task If for example data The method selected in the present were obtained implicating occupations study was to determine the lifelong beyond those already known to be occupational and tobacco history causative factors in lung cancer -- ---- of lung cancer patients and a control would be justified in assembling popu- group by actual interview with the lations of the occupational groups and patients The work history included the observing them for lung cancer inci- number of years engaged name of com _ dence rates study which would de velop more definite proof of the pany industry description of duties and listing of products and hazardous presence or absence of an etiological materials known to the patient relationship Several methods of investigation have advanced our knowledge in this sphere Data Collection . oan . : v First is clinical observatioonf associa tion between a case or a few cases of lung cancer and some exposure e.g. asbestos One defect of this method is that such clinical observation depends largely on chance and often involves such small numbers of cases that the validity is questioned Where made of course such observations are helpful Another common method of identi- fying suspect occupations in a highly fatal discase such as lung cancer is to Patients observed during 1949-1952 in 11 California hospitals three county . general hospitals five veteran or mili- tary two university and one private hospital comprised the study group An interviewer especially qualified in occupational analysis obtained the data froin each patient in the cooperating hospitals whose condition permitted the interview The session with each pa- tient often lasted two hours or more since many details about smoking were Sd oy a a ea es ed 2 en r 53 ey sae! <a Sins ON vee ote 1d Ot ee hee STE ath p ne ad a) woe LUNG CANCER VOL 44 = 173 obtained and the information about obtained occupation was highly detailed A total of 518 patients who finally had histopathologically proved diagnoses of lung cancer were ultimately included in the analysis For every patient in the case series another patient admitted to the hospital about the same time the same age within five years sex and race chest condition other than cancer or a disease was chosen in a random manner as a matched control Two inter- viewers one working in Northern Cali- fornia and one in Southern California hospitals obtained the data from the lung cancer patient and control patients using the same schedule in identical manner That interviewer bias did not enter into the determination of tobacco- i) usage history seems likely among other reasons because the results closely parallel those obtained in other investi- gations where such bias apparently was excluded and because the results for the two interviewers were very similar It is difficult to conceive how inter- viewer bias might have affected the occupational data since both lung cancer patients and control patients mentioned hundreds of occupations and none of these was suspected by the interviewers Preliminary findings were kept from the interviewers until the end of the data collection Method of Analysis Each record was reviewed by a physician particularly with respect to the pathologic diagnosis An industrial hygiene chemist completed the listing of materials usually involved in the occupations mentioned by the patients but not necessarily known to them Thereafter the data were coded and tabulations prepared Attempts to analyze the data concerning type of industry and exposure to materials already identified as toxic or carcinogenic did not prove fruitful Hence the major analytical effort with respect to work history went into the data on occupation itself This had been coded according to the Dictionary of Occupational Titles 2nd ed 1949 prepared by the Division of Occupa tional Analysis U. S. Employment Service a code with 367 three titles Particular attention was devoted to the question of years of exposure be- cause present knowledge of carcino- genesis due to environmental agents indicates that duration of exposure and a long latent period are critical factors analyzed Data on tobacco usage were so as to reveal the type and degree of smoking as well as the fact of smoking itself Finally an attempt was made to sepa- rate the effects of tobacco usage and occupations which appeared implicated Table Age Distribution of Lung Cancer Patients and Controls Age Tutal Under 40 40-49 50-59 60-69 70 and over Adeno- carcinoma "= 4 6 * 19 14 4 Cases Other Types of Carcinoma 472 22 56 194 15 46 . ToLai 518 25 62 213 168 50 Controls Total 518 26 59 213 169 51 y Nepi emt tb ve earl ~~. i - : a : LP ee, Ren Re eae a pera EE gaPt ee LeOkOT, BS in at bie Raver ; a a Aa 4 4 e oro pia 83 174 FEB 1954 AMERICAN JOURNAL OF PUBLIC HEALTH Table Sex and Race Distribution of Lung Cancer Patients and Controls Sex and Race Total Total male White . Negro Other - Total Female White -- -- --" -- Other Adenocarcinoma $ 97 97 : - / 3 1 o Cares Other Types of Carcinoma 472 7882 7882 7882 7882 22 22 3 3 Total 518 493 - 461 20 12 25 18 4 3 Controls . Total 8 6382 6382 6382 6382 3232- 323 Findings on Smoking Tables 1 and 2 reveal the distribution of the lung cancer patients according to their biological - characteristics age sex race and the essential similarity of the matched control series in respect to these characteristics Tobacco usage by lung cancer pa tients and the control group is shown in Table 3. Here one may note that 481 93 per cent of the cases gave his tories of having smoked cigarettes whereas only 394 76 per cent of the controls gave a similar history No such greater frequency of tobacco usage in other forms pipe cigar chew and snuff occurs among the lung cancer patients when compared with the con trol group In fact 68 of the control group used tobacco in a form other than cigarettes exclusively whereas only 15 of the lung cancer patients did sorelative frequencies which are not much Table Tobacco Usage During 20 Years Prior to Study Reported by Lung Cancer l'atients and Controls - Manner of Using Tobacco Total Total not smoking cigarettes No No use of totobbacco acco Tobacco other than cigarettes only Total smoking cigarettes Cigarettes only Cigarettes and other Adeno carcinoma 46 - ~ 6 4 2 40 31 9 Cases Other Types of Carcinoma 472 RR 15 "" "" 208 146 Total 518 34 19 -15 484 329 155 Controls Total 518 124 68 391 240 154 . Rar ed * Pid = 4,5 PIEPER cates "Ae, p eet 2 Sankety: ata he eu ae BCAA TS : get! LRG Saree CEE eg tia 2 LUNG CANCER VOL 44 175 Table Amount of Cigarette Smoking During 20 Years Prior to Study Reported by Lung Cancer Patients and Controls _ Packages of Smoked per Day Number Cases ~- Per cent Controls Number Per cent Total 18 100 518 100 None 34 7 124 418832 4 19 4 418832 50 105 - 71 14 418832 1 30 59 418832 80 199 2 or more 15 22 418832 Not recorded 10 2 18 418832 different for the nonusers of tobacco in , The two series This suggestion of an effect by cig arettes only is consistent with other in vestigations in the field Some support for the hypothesis that cigarette smoking affects the development of epithelial carcinoma of the lung more than ade- nocarcinomia may be noted Six out of 46 13 per cent of the cases of adenocarcinoma did not smoke cig aretics whereas only 28 out of 472 16 per cent of the patients with other types of carcinoma described variously as squamous epithelial undifferentiated did not smoke cigarettes One commonly used measure of the amount of exposure to cigarette smok ing the average number of packs smoked per day appears in Table 4 Seventy per cent of all lung cancer patients reported smoking one or more packs of cigarettes on the average per day over the preceding 20 years com pared with a frequency of only 42 per cent among the controls Excessive cigarette smoking two or more packs per day occurred almost four times as commonly among the case series as among the control group Other items which may indicate the amount of cigarette smoking include the age at which the individual began sinoking whether or not he smokes before breakfast and whether or not he inhales Table 5 reveals that by all Table Age of Beginning Cigarette Snioking Sinoking Ilabite and Cignretto Cough Reported by Lung Cancer Patients and Controls : Cigarette Smoking Characteristics Number Total Total cigarette s 'nokers Degan 15 years of age Began 15-24 Began 25 years of age Ishale Smoke before breakfast Cigarette cough 518 484 166 286 32 449 373 204 Cases Per cent Based Cigarette Smokers Only 8387872 8387872 8387872 8387872 8387872 8387872 8387872 Per cent Based -- Total 82330628 82330628 82330628 82330628 823 0628 82330628 82330628 82330628 Number Controls Per cent Based Cigaretto Smokers Only = cent Based on Total 518 8 394 828 * 116 828 2517 243 828 2517 35 * 2517 327 338 2517 229 338 # 112 338 2 ue Ry . a = aie | G So = av id ee ony thts one rece bt diel Wa tg anwerma A fre we en: " Po Vwwa bars 5 rev. . 1 Me. < Mleaf 4 * i Fhe TK cn a re rans n 4 ber, \eaere tae ee 176 FEB 1954 AMERICAN JOURNAL OF PUBLIC HEALTH Table Estimated Prevalence * Rates of Lung Cancer per 100,000 Males of Sclected Ages and Various Cigarette Smoking Habits Number Lung Cancer Control Estimated Prevalence Rates Quantity Smoked Daily %* Heavy All Quan tities None Relative Prevalence $ Heavy ---- Quan tities Patients aged 50-59 years 1. Doll and Itill 276 275 Ex 27 2. Wynder and Graham 258 210 Ex 27 74 NE 6 74 NE 11 3. Sadowsky Gilliam and Cornfield 198 208 3" $ 26 3L 4 * 4. Present 213 213 102 9 26 3L ? Patients aged 60-69 years 197 199 1. Doll and Hill 83 3R 2. Wynder and Graham 187 160 83 70 Go + is Go rs] is 3. Sadowsky Gilliam . and Cornfield 76 71 - FR 5 9 4 4. Present 168 169 2 78 17 25 S Estimated sccording to the metbud of Carafeld.41 Data for studira el Dull and R^...lWynder and Grabom and Sadowsky Gilliam and Com^/eld from the latter paper Quantity aaked daily oscept for premat study is all forms of making expressed as cigarettes wich pipus sad cigars converted to their equivalento in cigarettes an follower 1. Doil and Hill ou al tobacco a weak = 4 cigaretini a duyt 2. Wynder and Graham nigar= $ cigarettes ^ Corndald cigar = 10 cigarettes 1 oz pipe tobacco = pipaful cigaretion = 2cigarettes d For present and 3. Sadowsky Gilliam sod present wady quantity moked daily includes only cigarette amek ng Relative prevalence in the ratles Henry among heavy rmakers among unsmokers all queuticiso amang smokers among nonsmokera ~ ** Heary umaking is de nedas the following number of cigarettes or equivalents of cigarettes per day~-Dell and Hill or more 1. Wrader and Grahem or more 3. Sadowsky Gilliam and Cornfeld se more and 4. premal study or mort of these criteria the lung cancer pa tients smoked cigarettes to a greater extent than did the control group Also approximately fifths of the lung cancer patients stated that they had had cigarette cough usually antedating the onset of their illness by many years 120 said that they had had a cough for five years or more The frequency of such cigarette cough was only about half as great among the control group and only 39 of the control patients indicated that their cough had lasted five years or more Significance of Findings on Cigarette Smoking The data clearly show cigarette smoking to be more frequent and intense among lung cancer patients than among the control group Our data parallel that of other recent well controlled studies all indicate a positive correla tion between cigarette smoking and lung cancer a correlation which increases steadily with the amount of cigarette smoking One can hardly escape the conclusion of Doll and Hill that smoking is factor and an important factor in the production of carcinoma of the lung and the more recent con- clusion of Doll The results amount I believe to proof that smoking is a cause of bronchial carcinoma The cigarette smoker or prospective cigarette smoker may wish to know how much his chances of developing lung cancer are increased by such smoking Acknowledging that a correlation exists one may still inquire how many times does cigarette smoking increase the . teeeiay. ~ "SERA: Wee te td lp PR a eB OT EY RE4S I>ae seal 9% : vi ae pit AON Be oY Tae Re mS Tenge ^' = Mir r larag = ES Sue ie Ne; ee mais BS BS x rats Ss A SMPeRa Ort O eee an, ate os Of cera Seg OM ne. * ore Stet ty ad ww ceeane seers LUNG CANCER VOL 41 177 likelihood of lung cancer what is that likelihood in Further absolute terms To answer these questions definitely would require that records of cigarette smoking for large numbers of persous in the lung cancer age be assembled These persons would then be placed in categories with respect to cigarette smoking e.g. nonsmokers moderate smokers and heavy smokers Finally they would be observed for a sufficient length of time to determine the rate of lung cancer among the various categories of cigarette smokers and the nonsmokers Such studies are now under way devices However statistical devices have been developed for data such as those in the present investigation which if one is willing to make certain assumptions yield an answer to the question how many times does cigarette smoking in- crease the likelihood of lung cancer Application of Cornfield's formula 11 iz to the data from four studies including the present one Table 6 indicates that for men aged 50-59 the prevalence of lung cancer is from four to 11 times as great among smokers as among non- smokers and from seven to 27 times as great among heavy smokers as among nonsmokers Similar ratios were found for the 60-69 age group This formula involves the assumption that in so far as smoking history is concerned the patients are a representative sample of all lung cancer cases and the controls are a representative sample of all other persons in the general population Findings on Occupations As noted earlier the records for lung cancer patient and controls showed all ( ) Table Twenty Per cent Sample from Complete List of Occupational Groups ^finWhich There Were at Least 5 Cases or5 Controls Employed for 5 Years or blore Occupation Persons Employed in Occupation at Least S Years Cases Controls Authors editors and r^'portera Ship captains mates pilots and engineers Clerks general office ** Canvassers and solicitors 11 CONATIevo omng Salesmen to consumers Waiters and waitresses except private family 14 omngomng Policemen and detectives public service Animal and livestock farmers Farm hands animal and livestock 10 General woodworking occupations not elsewhere classified Painters except construction and maintenance Brick and stonemasons and tile setters omnyo F6-80 Construction occupations not elsewhere classified lucomotive firemen Attendants filling stations and parking lots Mechanics and repairmen not elsewhere classified Kotes Sample randomly selected from the 81 occupation groups which mat the stated frequency duration requirement at least 5 cames or 3 contrain with 5 years or won employmest Occupo- tims clomided necording to digit categories in the Dictionary Washington D. .: U. S. Employment Service 1949 Dictionary of Occupational Ocupational Titles 2nd ed Dht t <3: + An? 7 deg 32 4 bey Meg we? 4 ;, rf p-fo-- q q - q q Ss | ead akey 178 FEB 1951 AMERICAN JOURNAL OF PUBLIC HEALT Tubla Occupation Groups in Which the Frequency Einployment Among Cases Was at Least Twice Great as Among Controls of 5 as Year Occupation Persons Einployed in Occupation at Least 5 Years Cases Controls C16 Engineers civil STOM 138 Stock clerks STOM 266 Policemen and detectives public service STOM 430 Lumbermen raftsmen and wood choppers STOM 473 Machine shop and related occupations not elsewhere classified 450 485 Welders and flame cutters 450 520 Occupations in production of petroleum 450 523 Construction machinery operators not elsewhere classified 750-55 524 Brick and stonemasons and tile setters 750-55 538 Brakemen railroad 750-55 570 Firemen other than process firemen 750-55 573 Cranemen derrickmen h istmenand shovelmen 15 575 Dritlers extraction of minerals and construction 750-55 S333 S333 S333 S333 322 322 2 MISNON MISNON MISNON MISNON MISNON MISNON * Orrspations classified according to the Dictionary of Occupational Washington D. C.1 U. 5. Employment Servico 1919. Includes only occupatione at least 5 cames with $ yours or more of employment Titles 2nd ed in which there were occupations followed and their dura the numbers pertaining to any one oc tions in years A listing was prepared cupation would be less impressive than of the occupations pursued by at least in the case of cigarette smoking How- five patients or controls for five years ever the frequency with which the lung or more This listing revealed 81 occu- cancer patients had pursued certain oc pations in this arbitrary frequency cupations was substantially greater than duration category _ Table 7 presents a random sample of these occupations and the number of patients and controls who at some time during their work history had been en- the frequency with which control patients had pursued these same occupa- ; tions The occupations for which the fre- quency among cases was at least twice gaged in them for five years or more It will be noted that among the 518 lung cancer patients seven had worked as great as among controls using the same frequency category as before appear in Table 8. Such a tabu- as authors editors or reporters occupation for five years or more and among the 518 controls nine had been lation of course shows the occupations classified according to an arbitrary code which was not devised to reflect com- similarly engaged Relative frequencies of occupation would appear to have the same logical significance as such fre- mon occupational exposures that might be responsible for lung cancer Further analysis therefore included the de- quencies of cigarette smoking The lat- tailed examination of records of in- ter is of course much more common dividual cases and controls and re- among both case and control groups than is any single occupation Hence grouping of occupations according to possible common exposures For ex eat, Paso?d reas, ete al athe BR ete end ee ret ey . me wees air ah "GE Ba : Pa SO EGE sory y. cS a ry cos Ra har B Si ON Ee,= ie htc ROS Sn . LUNG CANCER VOL 41 = 179 ample one occupational group number 530 plumbers gas fitters and steam = fitters showed 16 cases and 10 controls with a year employment history Examination of these 26 individual records revealed that substantially all the difference between case and control series was due to the steam fitters who had a heavy exposure to asbestos It was also noted that other types of work involving asbestos occurred more fre- quently in the employment history of cases than among the employment his tury of controls Thus a new category including steam fitters asbestos workers and boilermakers involving expo- sure to asbestos found to occur 10 times among the cases and only one time among the controls Table 9 presents the data for occupa- tions grouped according to possibly significant exposures Although num- C C C C bers in each of the categories are small the differences between cases and con- trols appear to implicate the occupations listed It is of interest to note that several of those with the most striking occupations may be involved in lung cancer In recent data of Doll the only occupation with an important excess in the cancer group was that directly concorned with the production of gas Little or no support was found indicating that other occupations suffer special risks However Doll's study was based upon experience in England where the employment pattern differs from that in the United States especially California Also Doll used an occupation code of only 76 entegories which may have been too coarse to reveal the differences found in the present investigation where a code of 367 categories was used and analysis carried to subgroupings of these It may be noted that 77 persons with lung cancer had an exposure of more than five years to suspect occupations unduplicated count in seven occupation groups according to the data in Table 9. This number represents a not insignificant proportion of the total 518 lung cancer patients in the entire differences involve exposure to metallic particles and fumes and products of metallic combustion This observation tends to corroborate the suggestion of Wynder and Graham 13 that hot metal study present A further question upon which the present data might be expected to throw some light is the extent to which ciga- rette smoking and occupations operate Table Cases and Controls Employed for at Least 5 Years in * Selected Occupation Groups Occupation 1. Welders and sheet metal workers deing welding 2 Sicam fitters boilermakers and asbestos workers 3. Electric bridge crane operators industry . 4. Occupations in the extraction of lead zinc and copper ore 5. Marine engineers firemen oilers wipers and wipers cooks Construction and maintenance ~ Cooks commercial excluding cannery * Cephund Cephund Cephund os regrouping according to detailed examination of records Persons Employed in Occupation at Least 5 Years Cases Controls 14 211 10 211 S 211 9 12 22 35 occupational expome M022 M022 M022 21 alter d mice ;; | Cer hee ree . Be { . iw Ekit ead r | r % , : . ace: es ms ra Bits eee , a . \ x yas a A z a 180 FEB 1951 AMERICAN JOURNAL OF PUBLIC HEALTH Table Example of Adjustment for Smoking Applied to Welders and Sheet Metal Workers Doing Welling ~ None Packages of Cigarettes Smoked per Day 4 1- OT morn Not corded Total All cases and controls male , 1. Cases 2. Controls 3. Total 4. Proportion of cases among total cases and controls Welders and sheet metal workers doing welding male 5. Cases 6. Controls 7. Total 8. Expected number of welder cases 22 110 132 0.167 0 1 l 0.167 293 69 293 105 61 174 296 193 489 : 80 10 493 22 825 493 102 825 986 0.263 0.396 0.605 0.783 0.357 000 000 000 0.0 NON NON NON 0.792 272 272 272 7.260 1 0 1 0.783 a 0 0 0.0 14 2 16 9.002 9.00 16 Expected proportion al canes among welders = = 0.363 14 Observed propertion of ezera zmong welder = = 0.875 46 . 14 : ceat ceat Ninety per rent couldunes limits for the level Females ancladed from total gr^spsince saly properties = 0.617 0.9540.954 moles are ncluded la groups to signifcant statimlenily at which test was applied Obraised by applying the properties of cron among total eased and controls in soch umoklag cairgery number of welders in that amaking category line No. 4 ^ Uae No. 11 I Hald A. Statistical Tablas and Formulas New York John Wiley 1953 Note This test also was applied to all other occupation groups shown in Table 9. The group " bellermakers ambestos workers was on the borderline of watistical sign~ ^"canceat the 75 per sent level None acher groups met the 95 per cent level of statistical ^ cance 95 per to the Gitore, of the as separate factors in lung cancer For example both cigarette smoking and welding appear to be related to the disease but do welders get lung cancer more frequently merely because as a group they are heavy cigarette smokers Although data from the present study involve small numbers for many of the occupations analysis does indicate that welding as an occupation operates as a factor distinct from cigarette smoking in relation to lung cancer Table 10 The group of steam fitters boilermakers and asbestos workers lies on the border- line of statistical significance when the effect of cigarette smoking is controlled In the other occupational groups the numbers are such that the differences might arise from chance variation more than five tintes in a hundred However all the occupations listed in Table 9 deserve intensive study to determine their precise relationship to lung cancer One important step is to assemble populations of individuals em ployed in these occupations and with varied smoking histories in order to observe their lung cancer incidence rates These rates may then be com- pated with the rate for the correspond- ing sex group in the general population One may thus determine pay "ae SahOs BER EAS eee Se 3 qaVen eon: LUNG CANCER VOL 44 181 how being in a particular occupational group affects the chances of developing lung cancer and likewise how cigarette zmoking modifies these chances Conclusion The data in this study constitute still another link in the chain of evidence connecting lung cancer with cigarette smoking evidence which the New Eng- land Journal of Medicine notes to be su strong as to be considered proof within the everyday meaning of the word 14 It is time for those concerned with health education and with the ethics of advertising at least in health and medical journals to take note Further investigation should seek the exact component of cigarette smoke- tar arsenic or which is respon- sible The data also suggest that several occupations Table 9 in addition to those previously identified as having an etiological relationship may be involved in the development of lung cancer These occupations should now be intensively studied to determine to what extent persons engaged in them suffer special risk of lung cancer There after if an etiological relationship is clearly established the precise exposure and mechanisin responsible should be identified in order that protective meas- ures may be introduced REFERENCES 1. Def M. E. Dnit R. and Kenwaway E. L. Cancer of the Lung in Ariation to Inbocca Brit J. Cancof 3 1951 2. Schrek R. Diker In A. Ballard G. P. and Dolgoff S. Tabacca Smoking av an Etiological Fac toe in Disease Cancer Remarch 49-58 1950 3. Wynder E. L. and Graham~- F. A. Tobacco Smok Ing sa Posuble Etlalagic Factor in Bronchiogenla Carcinoma A Study of 663 Proved Caves J.A.M.A. 143 379-336 1950 4. Dall R. and Ifill A. A Study of the Aetiology of Carcinoma of the Lung Brit M. J. 1271 1786 1952 5. Lavin M. L. Coldstein I. and Gerhardt P. R. Cancer and Robecce Smoking A Preliminary Re- part 1.A.M.A. 336-138 1950 6. Hueper W. C. Occupational Tomers and Allied Discsses Sprlagfeld 11.1 Themes 1942 7. Rostel O. Saupe E. and Schmerl G. Dia Bergkrankheit der Eirbergleuta do Schneeberg in Sacharn Schneeberger Lancrubroba Zimbr . Krebsforach 23 366 68419L 8. Machle W. and Gregorions F. Cancer of the Respiratory System is the Laited States Pub Health Rep 1114-1127 1948 9. Clayne S. A. Preumocamionist Histological Survey of Necropsy Material in 1205 Caree Laprel 010 1851 10. Dell R. Bronchial Carcinomas Inuideuro and Antiology Part I and Part l Brit M. J. 521 327 583-590 1953 11. Commbold J. A Method of Estimating Comperative Rates from Clinical Date Application to Cancer of the Lung Brent and Cerviz J. Nat Cancer last 1069-1275 1951 17. Sadowsky D. Cilliam A. and Cerafold J. The Statinical Asciation Between Smoking and Car cinoma of the Lung Std 1237-1258 1953 13. Wynder E. L. and Graham E. A. Etiologie Factory la Branchingenle Carcinoma with Special Referance to fadutrial Exposures Report of 137 Proved Cont Arch fariant Hyg & Occup Med 221 1951 11. Editorial Cancer of the Lang New England J. Med 465 HA 195 Journal 25 Years Ago ADDENDUM to the January 1954 25 Years Ago In addition to the articles on the common cold mentioned last month the 1929 Journal p 419 describes an page booklet That Mean Cold by present associate editor of the Journal Raymond S. Patterson It was reportedly his first production as director of health education for the John Hancock Mutual Life Insurance Company the January issue p 94 having reported his appointment as director of health lucation Life Conservation Service of that company Dr. Patterson had already been the author of A.J.P.H.'s Annotated Public Health Bibliography for several years it having first appeared under his line in March 1926 8m Oy oe 5 "PAO apsantteteyFay TPESBd od ESSOLee rt Del : o peg ee SePpaR ewes ne-. oa ier UA tere ee: BIA wr STAC SapperLOLS ha (ar sh fie : bebe! BeBe Te: S83 age a =~G- a G eee AR PT te toh 4 - s ens 5 iE ~