Document x5xjYQm9Zj5LrB2N0JObdqw5m

#l. ; 4 -V 'copies toj KAI/JWj DGI/to); ; OTH. . i CONFIDENTIAL A fcjJ^L ^bv/- *< v`<t to m ^ 04 *X / /wr n755^ An Epidemiological Study of * Lung Cancer in Asbestos Miners *V^- # .%v DANItl C SftAUN, DUO., **4 T. DAVID TtUAM, M.A* Pitt*bwrk Ever since the pronounced increase in the incidence of lung cancer among males liecame apparent, there have been attempts . to associate it with one or another of the various elements in the environment of man. The approach umxI by some workers has been to su|>evt one or several sub/ stances and then set about in an intensive ; search for lung cancer among persons who have had any exjiosure to those materials. In this connection. Smith1,5 writes: "The tendency of authors reaming the coinci dental occurrence of primary lung cancer with silicosis or with any other theoretical etiologic conditions, has been to emphasize the percentage relationship in extremely small series of cases, with control ca*e* which are not in any way comparable." It would seem inevitable that asbestos should come under scrutiny in this manner, because prolonged exposure to this material is known to cause a sj*ecific type of pneu moconiosis, and because persons who show this form of pneumoconiosis often come to autopsy and provide a ready source of material for stud}'. It was in this way that 5. : reports of the simultaneous occurrence of lung cancer and asbestosis began to accu mulate after the report of a case by Lynch and Smith w in 1935. Within the next 10 years, about 15 additional cases were rejorted, and in 1954 Mcrewcther'* reviewed all deaths from asbestosis recorded in Eng land since March, 1924. Lung cancer oc curred in 16% of these rases. GJoyne.41 Accepted for publication Jan. 20, 1958. This study was made possible through a grant from tlie Quebec A sliestos Mining Association. Medical Director tDr Braun) and Statistical Consultant (Mr Truan). Industrial Hygiene Foundation. whose work is also frequently referred t as establishing a connection between ;isl>c* tosis and cancer of the lung, reported in 1951 that cancer of the lung was present in 14.1fr of asbestosis eases examined by him. In 1941. Xordmann ami Sorgc claimed to have produced lung cancer in mice which they eX]>o<ed to asbesto- du*t. Since 1951. additional eases of cancer of the lung coexisting with ashe>tosi> have been rqtoried. and. according to Huepcr"* about 100 such cases had been rei>ortod up to 1955. As a result, an association between the two diseases apjicars to have been ac cepted by many authors, and several writers were using the derm `'asbestosis cancer" of the lung. Werner.** in 1952. stated cate gorically that in 7*7 to \7r>t of cases of aslwstosis. after a latent period of about ' 1 x/i to 20 ye;cT>. carcinoma Ixxomes estab lished in the lung. On the oiher hand, not all authors ac cepted this alleged association without reservation. Saupe * in 1939 reported that he had discovered m. cases of lung cancer among 620 cases of asbestosis which he had examined; and in 1942, Holleb and Angrist 4* expressed the opinion that the number of case* of asbestosis with lung cancer wa io -mall for statistical evalua tion. in 1947. WVgclius ** rejiorted 126 radiiiliigicaHy diagnosed cases of asbestosis among 476 workers in Finland, and found no cases of lung cancer in this group. Goldhlatt and Goldblatt in their section of Merewether's latest book,44 state: "But at no stage in all these impressive researches wa any clue obtained which might have offered anv supjion to the |*issibilitv that asbrslo* could act as a carcinogen. There 634 PLAINTIFFS EXHIBIT , W'6b9m\ J.L'XC CANCER IN ASBESTOS MIXERS / N 7552 is no reliable criterion by which one can "scheduled" areas, by which is meant, anticipate, carcinogenicity and, as is well "those areas where processes are carried on \ *% known, relatively minute changes in the which were scheduled under the Asbestos structure of a chemical carcinogen are suffi Industry Regulations of 1931 as being cient to diminish or eliminate carcinogenic dusty." action. There is. furthermore, a complete lack If asbestos is indeed to be regarded am a of definition of terms as used in the pub carcinogen, the need is felt to demonstrate lished literature. For example, the term some property which can be regarded as "asbestosis," as used, may refer to changes something more than inertness.*' observable only by microscopic examination * These authors advance the theory that, until some more experimental evidence of direct carcinogenesis by asbestos or a de composition product of it can be obtained, asbestos might be considered as a "co-car cinogen" which only induces a further de- of the lung tissue, or it may mean a radiologically detectable condition. Most of the published reports obviouslyincluded women among their cases, but some of them do not give the number or proportion of women involved in the study. dopment of a prcneuplastic condition There is also a lack of uniformity as to drought about by something independent of what typn.* of exposure most studies have the asbestos, such as an endogenous factor. dealt with. Of 99 cases enumerated by Thus the literature, while tending to sup port the thesis that asbestosis is in some way related to the development of lung Huep>cr5* in 1955, only 10 appxar to have originated in the United States, and 7 in Canada. Some of the earlier reports ap cancer, is by no means unanimous. Alto parently included asbestos miners, but it gether, it is perhaps more confusing than ran be assumed, since 82 of the 99 cases enlightening. A careful review shows that had originated in England, and since no the majority of the reports are clinical and asbestos mining operations are carried on I not epidemiological. They lack many ele in that country, that most of the reported ments necessary fur the application of oase have involved workers in the textile epidemiological techniques to their content, or fabricating industries. and most of the authors-do. not make claim to having done so. What has happened is that succeeding authors have drawn conclu sions and generalized beyond the scop< of the works which they quote. Nowhere, for Such factors as smoking habits, family history of cancer, length of time in the industry, and age of the individual case are also notably absent in the majority of these reports. example, have we found references to a With this understanding of the limita population of asbestos workers, although tions of the existing literature with resjjeet l several authors who have quoted the ob to qndemiological generalization, it may be I served incidence of lung cancer in autopsies of value to consider in somewhat more de <{ persons who also had asbestosis imply tail some representative earlier publications, that this incidence applies to asbestos work a few of which were referred to briefly ers. generally. We have likewise been above. unable to find any study which actuallycalculated the incidence of lung cancer among a jopulation of persons who had aslvslosis. and not just those who came to autopsy. With the exception of a paj>er One of the most detailed studies and one which deserves the most serious considera tion is that reported by Doll** in 1955. This study reviews causes of death among asbestos workers Lised on coroners' rec by Doll.9" none of those reviewed gave any ords. It also attempts to estiipatc the risk data on exposure and #ust concentrations, by studying records of men who worked and even Doll's j<ajer merely mentions for at least 20 years in txpx>sed situations Broun--Truatt 635 i* m * ttAtVv ( * * *, M? Ddl! concluded .thafjungVcancef'.was a spe- Vfong omceriti other! fornu of ^pneuijjocorijtt-: V * cific industrial- hazard of certain asbestos *is was 6.7%,^and "in"' 169 caies ;which:1 w-o- rk ers an-dJ that, after 2**0> -yie-a-rji o_f*e--x--p-o- pro- ved. not. to have ~any type bf' pneumo sure, the risk is 10 times as great as for coniosis it was 8.3%. Gloyne considered the general population, - "the mortality of the asbestos workers" to- This article is important for several rea-' be "disturbing." First of all, it is obvious sons, in addition to the definite, conclusions that the paper does not deal with the "mor at which it arrives. For example, it begins tality of asbestos workers," and secondly, by stating that "in view of the infrequency it must be borne in mind that all of Dr. of asbestosis, this large number of cases . Gloyne's cases were submitted to. him for (61 cases of lung cancer) suggests--but . study' because the findings were unusual does not prove--that lung cancer is an for .uncomplicated pneumoconiosis... It can occupational hazard of asbestos .workers." ' reasonably be assumed that cases, including Neither this article nor any previous one those of asbestosis, in which the findings which we have examined presents' any fig-. were not considered unusual were not sent ures to prove that asbestosis is an infre- . to Dr. Gloyne for examination. As a mat quent occurrence. Estimates of the number ter of fact, in the same paragraph in'which of persons potentially exposed to asbestos he expresses concern over the incidence dust in the United .States alone vary from rate in asbestosis, Dr. Gloyne' himself 10,000 to 35,000, and the incidence of as-- points out.that the rale for lung.cancer bestqsis-qf any degree might be higher than. based on . necropsies at the. London Chest; Doll imagines, " '\- Hospital was 212% while the figures of This study, like so many others.' involves the Registrar-General showed only 2.4%. autopsy records. The number of persons He thus recognized that autopsies on a cer involved in -the statistical analysis is only tain selected group of cases.were not rq>- 113, representing only 1,042-25 man-years ' resentative of the. general population. It of life. It is also true that in selecting men would seem, then, that notwithstanding the who had been employed- for at least -20 ' value of Dr. Gloynqs work, its importance years.' the study ..automatically ...excluded as an index of the prevalence of lung can those who' died .from other causes -after cer in asbestotics has been misinterpreted shorter employment.-''V*. V' by some who have quoted him. .All that it Another reason why this publication is of importance is a statement which it contains to the effect that "the strongest evi dence that it (lung cancer) may be a hazard (in asbestos workers.) has been produced really shows is the fact that in a group of 121 cases,1 selected .for special study pri marily because they seemed abnprmal by; - preliminary examination, 17, or 14.1%, had lung cancer. J''V. by Mcrewether and by Gloyne."" Mcrcwcthcrn in 1947; in the report of In 1951 GloynC41 presented a review of 1205 autopsies on persons who had worked in various dusty occupations. This the Chief Insjector of Factories, reviewed all cases rejwrted between 1924 and 1946 in which asbestosis was the cause Y>f death number included 132 asbestos workers, of - or a coexisting condition. This work was whom 121 showed "pneumoconiosis"--pre later extended to indude all such cases re sumably, asbestosis. Primary cancer of the ported up to December, 1954, by which time lung occurred 17 times in this group, ah there were 344 deaths, including 205 males incidence rate of 14.1% for lung cancer and 139 females. Among them were 55 among asbestosis cases coming to autopsy. cases (16%) of cancer of the lung, 41 in There were in his series 796 cases with sili males and 14 in females. It is quite possible cosis, and 6.9% of these also showed pri that a large number of asbestotics who did mary cancer of the lung. The incidence of not die of their asbestosis, or in whose ;- ' - Vol. 17, June. /W i i I i. i* * death certificate it was not mentioned, may have been missed. The import of this 16% is enhanced by the simultaneous statement that the incidence of lung 'cancer in autop* sie> of the general (ujHilation is only 1%. The danger of attempting to compare a rate found in 344 cases with the Tate for the general imputation without resj>ect to age. occuialion. and many' other variables, such as smoking habits, is obvious. Lynch,'0 who with Smith * had rci>orted the first case in 1935, reported 4 cases of' carcinoma of the lung in a series of 49 autopsies on workers in an asbestos manu facturing plant who were shown to have .* `demonstrable deposits of asbestos in the lungs." This, of course, is' nt necessarily dentical with the disease asbeftosis. Lynch, himself, points out that, although this is an incidence of 8.2%. "both figures are too small for very serious statistical types of calculation.'*. Nevertheless, later writers have used this paper to strengthen the case tor an association of carcinoma of the lung with ashestosis. It is also of interest that KlotzM found only the same number of cases ot lung cancer in a series nearly 10 Mines as large, i. r.. 4 in 478 cases of asbestosis. ' llehrens. a> cited by Mcrewether.70 esti mated that, of 309 cases of asbestosis in the literature, 44 showed assticiated cancer of 'he lung--giving an incidence of 14.2%. This is an illustration of generalizing an ' incidence obtained in a group of cases which were undoubtedly rojmrted only be.ttH.'f v>me of them showed lung caneer. to * .<.ihl v hundreds of asbestotics whose were never refined. The same ap.i'C' to the conclusion of Teleky.*4 who p|iears to have reviewed reiorts of 39 .uiiopsies on (arsons with asbestosis among which 6 case> of lung cancer occurred. Inoirmation from sotirces such as these does .justify generalizations with regard to "rtality rates. Vrhaps no one has written so exten tti the Mihjert as has Huepe^*** iv>* he reviewed the oaws ** reported prior to that date and' enumerated a_total,^ of 99. Eleven of. these were tho^.;<Jht-r * cussed by Doll ** and may have been cases covered by oUict authors. Eight were dis covered by Kennaway and Kennaway** in an analysis of death certificates, and, unless Merewether's study was incomplete, these cases should have been included in-his re port Of the remaining 80, it is quite pos sible that the 31 contributed by Mcrewether and the 17 by Gloyne contain some duplica tion with each other or with those of other English authors. ' . - Principles of the Epidemiological g Method --^ Dom * has pointed out that much of what is now thought to be pertinent concerning the comparative frequency -of lung'.cancer in different population groups has been de veloped from the analysis of clinkalinaterial, particularly surgical , and autopsy records, supplemented. to some extent by the reported impressions of various clini-. cians based upon their personal observa tions. More recently, however, attention has turned to the systematic ' investiga tion of this problem by the same methods that have proved so successful previously in the study of communicable diseases, that is. to say. by epidemiological methods. \ In order to ajply this method of investi gation to the problem under discussion, we were of the opinion that a study should be. planned so as to provide <1) a well-defined Imputation group; (2) available data for all members of this imputation, including the healthy as well as the ill; (3) a sample which is truly representative of the popula tion; (4) reliable and valid observations ' relating to the problem of the study. A serious defect, common to most of the studies which have been reported, is that little or no information concerning the healthy people in the group seems to have been available to the author. In order to draw a generalization regarding all asbestos workers, it is necessary for a study to in clude living persons as well as the dead. j -- Tr*a* . 637 ' * - 'r <! '' V-/.V/'< ' - Limiting/thc investigaiion 'to cases coming be found in to ouiopsy, as has been frequently done in- but representativeof/thegepetalpoib^Iition. n.............e..a...r.l.i.e..r...s..t.u..d..i.e..s..,...s..t.i.l.l...f.u..r..t.h..e..r....r.e..s..t.r.i.c..t.s....i.t.s....u..s.e........I.t....i.s....t.r.u..e.....t.h..a..t...i.n..v..e..s..t.ig'at.i<..m.....o...V...;ases'from in generalization. The problem with which such a sample can furnish.' information we are concerned is whether asbestos valuable for research, but the^ise. of this miners experience more lung cancer than information in drawing generalizations is vb'-V* ..v4 does the general population. The answer necessarily restricted. It is the/obligation necessitates the collection of reliable infor of loth the investigator .and of those who mation on asbestos miners as a group, as read his rejort to make proper comparisons well as on the general population. and to draw only those conclusions Which .... * '' 4t .* '4 It seems advisable to discuss the differ ences between the epidemiological approach and that used in the studies which have arc valid and justified. A`good statistical study of cases of cancer of the.lung'oecurring in a group of autopsies can; lead to a *t .. `9 V:.v J *I. ;rV. \l( ; ,: m been reported to dale. A very important consideration is the fact that lung cancer, in spite of its increasing numbers, is still a, disease of low incidence; that is, in a given population not many persons will contract this particular disease. This fact, requires proper inference concerning'the frequency of lung cancer among -cases ' .coniing to autopsy. l*ut only' to such cases./; Tor in formation from such' a study toi. be pro jected to some larger group, 'it.is necessary that the autopsies represent a good 'sample ' that large samples or groups must be stud of that largeT group. To.assume/that such ied to provide meaningful results. is the case in any particular/series /is dan Recognizing the difficulty of obtaining gerous and likely to be .such large samples, most. earlier . writers There is some, danger that' the" figures deviated from the epidemiological method reported by some authors may be miscon and sought to circumvent the requirement strued as allying to asbestos workers or of observing well persons by (1) compar even asbestos miners, when, in fact,, the ing the relative frequency of cancer in vari author- in question do not make this gen- ous sites; (2) - comparing ' the'' relative ` -eralization. nor can the generalization .-be frequency of cancer in a group of hospital made for the reasons stated. ..Close'studyiof ized patients; (3) comparing the relative the re]*orts reveals that the percentages frequency of cancer in a group of cases cited relate only to the group`of .autopsies coming to autopsy, -v. covered by the jiarticular investigation. / - Attempting to compare two population The present, study, in contrast , to the groups, looking onlyat the relative fre earlier works,"has been planned.to,.utilize quency of cancer in -various body sites, . the qiidemiologicat method. ^A.-well/defined may result in finding a higher percentage ' group of asbestos miners'.has "been//estab relative frequency) in one of the groups, lished in such a way that it constitutes a when, in fact, the mortality rate of cancer go<xl sample of the whole population of of a particular organ is exactly the same asbestos miners in Quebec. Data for all in both groups. This is Very clearly dem members of this group have been collected onstrated in the excellent article by Dorn.- . and ^'.''zed. Those. concerning lung .am- The mortality rate from a particular cause is the true measure of comparison. It is apparent that selected groups such as hospitalized patients or autopsy cases may not be in any way representative of cer rrcc,ved most areful cons,dtrn*' tim. Details of the methods employed will be set forth later, but the type of.approach is considered to jemiit of fair comparisons and valid generalizations. 'v a larger group, ami that in dealing with Collection and Analysis of Data such samples, the observer may easily find A preliminary survey of potential source* more cases of a given disease than would of information in February, 1956, involved KV. - Vo! JT. June /<* * of the asbestos companies' ] with clinicians, pathologists, of City and Provincial health departmeatV 1955. All data regarding this' group were and of the Canadian Cancer Society, and then tabulated in order to determine the other interested jiersons. It was found that characteristics of the cohort.. For those who morbidity data, although somewhat limited, survived the entire period, reference was were available from such sources as the made to the physical examination results hospitals in Montreal and Quebec City, and and x-ray findings at the end of the period, the 13 cancer detection centers in the Prov- ' Those who had died were tabulated sepa- tnce. However, because of the high mor- rately, and the cause, of death' was tality in lung cancer, itseemed advisable ' corroborated by examination of the death to depend upon data relating to deaths, certificates. A further search was made. . These we found to be obtainable at the concerning those in the original cohort who.. vital statistics department of the Ministry remained unaccounted for when the living of Health in Quebec City. From the pre- and the known dead, had been tabulated.: - 'iminary survey, it was ajiparcnt that exten- They represent men who had left employ ' sive and detailed information could be ment through retirement or resignation. gathered with respect to both the persons Kventually, all but a small number of these employed in the asbestos mining industry were accounted for as either living or dead, .ind the mortality figures for the'general and in the latter event, the cause of death {copulation. was substantiated, in a similar manner, and Following this exploratory survey, the the results added to the original list of initial effort was directed to the collection dJeaths. c,-.. .* . ./.. f data relating, to all workers who had Death certificates for . the Province . of lecn processed through the clinic at Thel- Quebec for the years 1952 to .1955; inclu tord Mines since its inception in 1947, and sive. were reviewed in the department of similar information regarding .all workers vital statistics of' the Provincial. Health at Asbestos, Que. Data from the clinical Ministry, together withstatistical. Sum records included the age, family and per maries of the causes of deaths in tbePrqvr-r sonal medical histories, smoking habits. ince by counties. All cases in which death' number of years of exjxjsure, an estimate Was certified as having been due to'pri- *f weighted exjKJSurc. and the course of maiy cancer of the lung were examuted for the individual's health status or the cauie such information as place of residence, of his death. occupation, date of death, hospital in which From this information it was possible death occurred, and 'whether Jor Wot ^an/: * in formulate a "cohort" which could lie well autopsy was performed: defined. should be representative of the lung cancer was given as a cause of death, ". whole group, and could be followed for a but in-which it was not specified as to definite period of time. All of the available whether the cancer originated in the lung, xpcrience indicates that the development were also reviewed in an effort to include f asbestosis in less than five years of ex- all instances of primary, carcinoma of the /Mire must be somewhat rare.. Accord lung in the study. . \ - . r. ingly. the cohort was defined as including The statistics for the Province of Quebec `cry miner who had a total exjiosurc of relate to population, total deaths from all me or more years, and who was on the causes, total deaths from cancer of all types. employment rolls in 1950. Office and other and deaths from lung cancer. These were *tK:xjK>sed personnel, regardless of length collected and tabulated by counties and by * employment, were not included. This sex for the vears 1950 to 1955, inclusive. ' '.turn TrmJn 6lJV w-y*. * * , *a 'l *.1 V* . rI i: -I A. ARCHIVES OF INDUSTRIAL UEALtJl- "From ..them,'' death` riles ..for. the general "-..."'In addition to this analysis'of deathslx^' * - *-* .J*_ *,. ., population of -Quebec and of individual curring in the cohort and during the' years counties' were calculated for specific years under observation, every known death from and analyzed by cause. cancer of. the lung, as well as every cast- Practically all employees of one compahy diagnosed but still living, has been .tabulated are covered by a group policy of life insur and analyzed. They wiU be discussed separance which, fortunately, nearly all of them ' ately from those included in the population continue to carry when they retire. A very ind time-interval under study. few are not covered by this policy, and A comparison of lung cancer mortality those who leave the industry for one reason in the asbestos-producing counties has been or another except retirement usually are made with that in counties which arc far no longer covered, but this is likewise a removed from the asbestos'mines'and in small number. As an additional check upon which, presumably, no asbestos miners live. the information obtained from the jclinical records on this group, the records of the life insurance company were examined for all death claims paid under the policy, and particular notice was taken of the claims in which the proof of death was based on cancer of the lung. Finally, in order to broaden the compari son of death rates in different jiopulation groui*, the rates have been collected for Canada generally, and for the United States, according to the most recent published and unpublished material. .. . Deaths from lung cancer among-asbestos Results and Interpretation . miners were thus determined from the clinical records in the medical service of the industry and checked by means of the death certificates and insurance company records. The deaths were then verified -individually by reviewing them with the physicians in charge of the medical sen-ices. In this man ner, there was established a list of cases in which primary cancer of the lung .is con sidered to have been proved as the cause of death. A few cases in which lung cancer is strongly susjiected but not proved as the cause of death were considered separately. Mortality rates have been calculated using both the "proved" and the total of "proved" and "sus[*ected" cases during the years un der observation. Comparisons were then made between the death rates from the same ' The cohort which was constructed accord ing to the criteria described in the preceding section has been considered individually and compared with the general population. Description of the cohort will be presented here as a preface to the results of the study: Original Cofori Lom IVrMni ltnlun<-t Final Cohort Living in 1955 (vkm* jk! retired) lVad by 1955 Cancer King Quftiotu)4f cancrr of lung Other rautt* 1 `nluMn causes Smalm .VwufBnkrrt rtkiwuit (.091 tsj J.9i t S.771 IK 9 3 360 , *> 4,673 UCS 2v Tables 1. 2. 3. and 4 present age, numlier of years <*f employment, weighted average ex|osurc. and smoking habits of the cohort. cause among specific segments of unrxj>osed ftersejns. All lung cancer deaths, both suspected and proved, were carefully ana lyzed to determine |ossiWe relationship or A comparison of the exposure to asbestos dust is presented in Table 3. AH members of the cohort were placed in one of three categories, representing increasing degrees correlations between the development of of exposure based on a weighted average lung cancer and any factor known from the of the years sj>ent at various levels of clinical records, such as family history of dustiness. The degree of dustiness for each cancer. jersonal history of heavy smoking, job category wa determined after consulla- coexistence of asbestosis, or cxjiosure to tion with jersons familiar with the environ asbestos. ment and conditions in the various work 640 f.'l IT. Jufir. 7".<\ / i Anno A(i___ * Lea ihu 04%. dWS, ,# * MO fwi 9( ampfaymaat.*--. .* areas.' For the purposes of calculation, the ually smoking more than five cigarettes per assumption has been made that the relation* day. Persons who smoke pipes or cigars ship between these categories is linear, and exclusively were not considered to be smok- that Category ,II is twice as dusty, and \ ers for the purpose of this stu Category III three times as dusty as 'Cate . Table S presents the year-by-ytar -ex*' gory I. - perience of the cohort and -indicates' the . : v*.' TASLt 3.--Number and Percentage Distribution by Exposure Category Table 4.--Number and Percentage Distribution by Smoking Habits - : Expoeuro Cmconr . 11 ................I UI.......... . Unknown_________ _ Totals_____ ATtnp Eipoourr.. Lett than 04%. r. . *. .' - Number "I'rr Ont acai aiso I.77J t MSS *4 44 M 00 too Cmaklnc - Habits 8uokon.._......... NUnokonsomwno_kor*._... Totals,l.__ '--11 . " t ~ than 04%. . r ..Nonatwr * P0t;/. .-4,070 , -.-It v*. ____...' 14** .. ..? ,*Y : ----- \-V-. T-- `>> C7=M7 b. ... *'*00-. :r- - . --- X - The fourth variable, smoking habits, was number of deaths each year from specified similarly tabulated and is >hown in Table - causes. In general, a case was 'considered 4. This was include! because the informa- to be "proved" as one . of jirimary ''-cancer* tion was available and because smoking was of the lung when the reaiirds showed thatregarded as one of the variables which, the diagnosis had been supported' by an besides the environment, could conceivably autopsy or surgical resection of the lung influence, the development of lung cancer. with microscopic examination , of the ^re As used in this presentation, the term moved tissue. In one case so considered. smoker refers to.a cigarette smoker,-habit- . however, diagnosis was confirmed by bion- Table 5.--}'ear-by- Year Experience of Cohort end Death Rates per 1D0K)0 ~ _ Man-Years of Risk Caueeof Dlb Yiwr ' S. Ab* At Reclantat of Yoer Pwnd Prim*/? Cla. of Laos femeftad Primary CO, of Lust Other Coueee IVAO................. ... IBSl................................. Utt?............................... IU............................... IBM .............................. IBM................................ MB AM2 MB tJB* UO A110 ' 1- > 0 > 1 s ' s 1 0 0 *13 r17. . >4 SI St. Totals___;............................ # t tee "f'rov^ " mir per 100.000 man-rears of risk- _* - KJ Unknown .* e v : *' i : .04 0 MtB-Yeor. . of Rttfc - *SJ714 "Total" ntr per 100,000 du-jwi of SAD ffrnun--Truan m I ' -CWNa:.svW "'im v -e"*<0' *V`a ' m' S 4 4M S tm 40 1 M r * m"V, -. *'*. JmIhr ^ dvje>,v -nxpomtn Jy'-f -j*. :V -.-.s . , jt . * f"* -i'n teow.tt A*** V, Mn-toOtU . W\m STjr.toCat.lv Vo nn.toCot.i':. Too S jt. toOoL.U To* UjTT. to C*1. in Toe ton-to Oat. U - Y* ttyr* to Oat. I * tto * yi- to Oat. XU - *-** J-***& a-jp-ao *) 4-WM - ll-B-H - 41 ' No; '. VT. ".NoV - \ Vo* -. ... No'- .. Vo. "C-*.-. '.' Y# Yo* Y* Mm Yr* . Vo* S<*-.--. Kmrvti... V.;' No * ", - choscopy with visualization and biopsy.. In would be very close, touthe..^5% jtVwel another, although there was no autopsy, the of significance. However,haying. foUnd just diagnosis of primary ouicer. of the lung 12 cases,'we are hot' above-this: level;'-and *. * * * ir'. *k seems to have been beyond question. . therefore the hyjiothesjs thatasbestoS miners The term, "susjwicYed". primary' cancer of . do not have a fitter mortal^ r the lung was applied tothose caies in cancer than does the general populatioriCan- which the-diagnosis remains in doubt but _ not be rejected. Nevertheless, the.occur- some of -the .evidence' joints to cancer of )lhe rence of 12 cases ;.m Situs' ^&.*$pu1d ` . lung. There were three such cases..- " increase the rale to a point Which appraache> The term "man-years of risk'* has been the significant level. Because of the tre used to mean the number of men ax ride .../snendous tmjxmance oT the 'cjueslionablc for the year under observation. A person who lived throughout the year was .counted as a full man-year of risk, but one who died suspicion .-o during the year , was counted -as one-half a cancer of the lung Hs `based ^hpon;:thc -ray - inan:year.`v ' interpretation,' and, although no auu^tfylwaj; Deaths occurring in the cohort, and in performed, the death certificate'7-indicates which lung cancer is considered to have that death wa due to lung cancer.. li` if been proved as a cause, are shown in Table wdl known that the x-rav appearance ni 6. In Table 7 are shown, three deaths which fibrosis) especially if a localized dwisity^or have been considered as `"suspected" Iting . ) a suj>erimpa.<ed tuberculous lesion .ds jprei- cancer cases.'' * '\ ent, can' simulate that of a tumor, )aiid) by An indication of the imjx>rtaice of these - itself, does not justify the. iridusion of-ibis 'suspected" cases in interpreting the results .^case'.-as .one of the calculations is desirable before fur ' lung. A second av V-as certified as having . ther discussion of the mortality rates which died by reason of hvdrothorax, possibly due are derived in later tables. For example, it to lung cancer, but again there was tin hap]*ens that the rate found for the proved surgery and no postmortem' examination. cases is dose id the "expecied" rate' based In the third case, although it was subjected on the genera! population figures for the to autopsy, two pathologists disagreed as to Province, as will be shown later, and on whether lung cancer was present. The death. this basis we should find eight deaths from was certified as having been due to chronic lung cancer among the cohort. Actually, myocarditis with nephritis and pulmonary. nine cases wen: observed. If, however, the . congestion, and possibly cancer'of the lung. ~ 3 additional "suspected" cases * were in On the basis of these farts, it seems unwar cluded, increasing this figure to 12, the total ranted to include these three cases among Tassx 7.--"SusftrlrF Primary Cmrrr of thr Ltmg CwN. I S J At* 40 44 took** r Yo v*. IipMOW 3 yr. la OtL tfl PM IO-3V-OR 7o--ao--Uot Amopif No Yh No AObMtoUt No Ye* No other hand, (hey cannot,'j|n fairness,'be di*-' regarded completely. Jt is for (his reason Xiahr W hnow and Komhcr af lane'Cancer 'Deatlia ( that mortality rates have been calculated both ways. . ": Locurth of ' Rjpphijrmact - No. at - Parma Prorad Tl - Table 8 gives the rates by age groups: The rates by length of. employment are shown in Table 9. During the first 40 years x>f employment, the,rate, rises, an observa tion which seems plausible' since, (be men- *0-1*..._______ r____ .................... KM*....... ............... Tecaa.____ ; 1,7*6 . -'.Jv-* ji'i ; im a tea - . .* . i ......... . t' IM . : ... ' . v' t' ,a -' AS* '. . *> - a were growing older. However, after 40 . -Aaoaal years of exposure there are no "proved"., - *" *r . * 'Laacthef" cases reported for a total of 240 men dur JCtthifmanl Until Kale*. aa-Ycar* at Eapeaarc .... (1100^00 * V* *.* i.- ; ^TomT.; ing the six years, or about 1440 man-years of exposure. When the "suspected" cases are added, one case does show* up in this KM*......... ................ . SO-3B....................... 40-4*.._................ 10^a . .*... .....a . a . , `a .1 *. :J- - V. *7 - - US M's s* . --S.!; Table 8.--Lung Comer Deaths by Age Cremfi Orrrall__ y .. ' ;r - Number of Person* and Number of' Loaf Cancer Death* . .' ; * . As* Droop * * -V No. of Death* No. of - f Persons Provod Total . dicates*' that the members of -the cohort did not die from Jung cancer at .a younger. ! age than the general population. - 90-44. 45-64............................ ss-m............................ I'nknovrn................... UN CIS St* a `1 '1 a 4 0 1 .The rates by weightcd' exptKure air S S shown in Table 10, and it will be 'noted * 0 that they present strong evidence against Total*........ 4SX - % 13 asbestos being a carcinogenic agent, lor, if exposure to asbestos `is in any way .con- Annual Lunc Cannrr llrath Rate* *<* 100,000 Man W Kapmurv A*r rroup Proved Total XM4............................... 44 4.S-44............. IS 44 *Ms-+......................................... aani aaui t:nknwm................................ . . 4> -. 4 Overall................ 36 nected to lung cancer, we would expect, that the longer and heavier the'xjo*ure;' the higher the rate that would be found. The only possible error. in this interpretation .could occur if-the weighted exposures were in tersely related to years ofcwipJoyrnait, * . " *ajK.-ri<Kl. This would produce a'rate of 69 Takx IO.--l.tmq Carutr Deaths by Exfnsure \ `Category X.-'if-i- ` ^jter 100.000, again demonstrating "the im-; -- N'valtr of Htrwu and Kinkrr at Lane Cmetr Death*' jKirtance of these questionable, but -un No. af Daatbi proved. cases to the final conclusion, Ktpnaurr No. of - CiUpry ' rnm Provod Total liecause, if there were ho cases in this I........ tJB\ 4. 4 number of men w ith long exjmsure, and if II........... 3.1*0 s 4: Ill......... ijn -* 4 asbestos is a carcinogenic agent, it must be Cnfcoovrn.. s 0 . . . > concluded that these 240 men have demon Total*. s,u ' w. strated con.siderablc resistance. This is a bio- Utgical phenomenon which has been observed previously and is consistent with the theory of an intrinsic or endogenous factor in can cer. The only otfWr explanation would be that the susceptible members of this age figpup had died earlier of lung cancer. Table 18. which appears later in this section, in-. Annual Unt Cancer Death Rate* per 100,000 htan-Year* of s|mrc Etpnaure Catefory I................................... II................................................... Ill.................................................. t'uknoan..................... ........... Provd SI tt It 0 Tota SI SI V 0 Oeoroll....................... a S4 Hb-- Trune (Ai r * '( \. ( # . w - - . W.ULhl*! Ktpoaor* : tkralk- lM(lb{ Kaptnjraant ; I IO-I* B0-M . B0-B0 - - m on B14 X7 M M ``C* ut.. k*m ' BM . ow ' '# BU Wl . 1 BM .* Btt` S BIB . . IBJ . . *7 41 'I - * ft ` M Tnul tnt BAM on BM mu Bidotan................ ..4JT* Ntanttm___ r4A* Unkaova...... ...... BO Taut*............ N. f DmUk Taut 4u e Ao : w* Tout* ba*> Avene* ln eleipomn. tti au- o . L.771- . BAM- ..w, iu :.a >. v P* - -f i- ; Annual Lone Cancer Death Rate* per 100.000 Man-Yea*' at Expoaurt kj Smofeiac Hebrte' >. - . ` ;, \ - " .. 1 in which . case the heaviest* weighted ex-. insure (Category III > . would : show' the shortest length of employment. Table 11, --* .*< ,, jn-` Smoker*.:____ __________ Konsmokert___,, ..I-, C Rbioaii...........-. : No.f frmthi -Trend . : - . 43. .0 P which lists the number of personsJn various ` Over-uU exposure categories by length of - employ-, ment indicates that this error has not oc curred. In fact, the average number of years of employment for each exjxmire category is almost identical. :v . - smokers, may. have included a .larger jjercentage of young men. .-Consequently; aid ditional Tables,13,.14,and 15 were con structed to showthe distribution of.'smokers * Table 12, which; develops the rates for and nonsn)okers' b5- agc, ;kngth -of employ smokers and nonsmokers. Is most Striking. ment, and degree of exposure. Although It shows .that not ai' single..'case of lung cancer developed among the 1265 nonsmokers and that all cases of lung cancer, both "proved" and "suspected." occurred in there are" slight differences, they do not account for the fact that all observed case.of lung cancer were'in smokers. In rcsjcct to age (Table 13) the combined average smokers./ V age of the smokers was 4.9 years less than Table 12 was so striking that it. was felt that further verification was necessary. It was possible that some abnormal distribu that "of the nonsmokers. Table 14 shows that as far as length of employment is con-` tion may have occurred, e. g? the non- Tajsu: 13.--Number and Percentage' Distribution of Smokers and Nonsmokers by Age Croups Table 14.--Number and Percentage. Dislribuium of Smokers and Nonsmokers by'Length '. .'of Employment. ar Koabr L*ncUt*f -. 'Cmptspouat Smoker* Koexmoker* :-t7hkDo*ni Aji Oroup . . . Beooi.tr . BO-44......................... 45-M....................... . B0-A*....................... M-................................................. Unknon_................ T*l_______ Irmtitp....................... baoo tat 411 104 B M l. 1 -4A7B K1 ' Ktmsekir - 2* BBS ISO ---- iam 4U Vskam u 4 3 1 1 -- 40.7 M-i#...................h. 1H0................... ............................. Ml.................................................. 40-48........................ *0+.................................................... Tm*1* ........ A**fM teoftb tt mploTVeul____________ " 1,401 Vi1AT TB 4 110 n im i;a BTT as m IM 75 37 1AM ' - W -v : 4 - - -- *' 4 8 0 .' 30 I0A 14 rmUK DMstboitoa kit Oroap -Batfar Nansmoker 3fr-44... ................... 41-M.................... ........ M-M.. . BM-....... '........... vsknewi............ 4KA 1*4 * BA - BM A . B4A 17.7 UA UA A TvtMi........... M0* M0% tlnknwa 0A BOA 10A A A ^mnrn -. wo* * l**lkuOA%. rmto DtotstbsUon' IunnbM EilUilnjTeni Bmokr Nonmokar Unknown -b ................ ........... :______ lo-to :.............................................. -................................................. BO-BO............................ 40-49........................... ....... Tculs............ B0.I 43.1 15.4 A 1.4 .7 KW* B0J S1.7 14.7 U.1 U .. . .. ' J\ 100% .BOA A I0A BOA 0A 0A . M0% 0*4 l ot. X7. June. IISS K M* X ;; / V ' i*?- ... - -. vv ir" ,Tale If--tfunberCahd Pcrc'ntape P^fnMcm'^JDcmography in the'ProYincul Mim3ry*^bf <*/ ' Smekerf>m4 Jiontmoktrt; W?->A rh ttioUt, TK" 32&*TCft? Expotvt* C#*9av*&t-r' -- -----------:--------- . ' from all forms"of caihcer, iod dcaths lfrom F-tpownt Numbar . cancer of the lung Were obtilihcd by sex Cawturr JaMtm S'Mimkm Citaon * and by county for the years 1950 through 1..............................: It........................ til............................. Cfakuoa'D.................. Touts......... Arrraaa cipoaurr raietorjr. tau l.WI - 1.434 .4 i.n XJ) 474 413 a t .. IJ* . u -7 4. a 1955. In addition, all death'certificates which sjwcified primary cancer of the lung, and all those which indicated lung cancer :. U but did not specify the origin, were exam ined for the 3'ears 1952 through 1955. .' * PrrrroUAr Dfalrtboito* - Table 16 gives'* tabulationof the number Ki|o*urr Cairno I* II.............................. Ul . ........ InkMaa.. amokart. XU M.I ' anj - 4U SooaDokan . ar'i v *4.7 ' o.t tikiaa . *04 UJ> 4tO a of deaths from lung cancer in the. Province and in the cohort for the years 1950 through 1955. and shows the' annual rate per J00,000 in these segments. |t will be noted from'the Tul.... . 100% w>% table that . the . mortality * rate for the "proved" cases in the cohort is only slightly evened, the smokers had worked about 2.5 higher than the rate for the Province. years less on the average than the non- When the "suspected" cases are included in smokers. With longer exjosufr ind greater the calculation, .the rate for the cohort rises age. one would expect the ' nonsmoking .. 35.8 jH*r^JOO,QOO,,_>'hich .is about 50% group to ihtjvr z higher rateif liing ranccr;^'^er,l^fit^5 rxtcHor thePro\mce.THis,' were due to asbestos, Table 15. shows thit -from the-prt^i^us dis- the avveerrage cxx|jKto.ssuurrc categoriy" was ailnHKt -' *-*H>'5'on 6f the effect of the suspected the same for the two groups. Therefore, cases on the results,' approaches but does this variable seems to l>e dl no irnj<ortanic not exceed the significant level. in accounting tor this difference. \ One further interesting observation -from The result of this additional .analysi*;-!-. that none of these factor's appears to lovyi the erted i Table 12. C'-mforis-'n t'f the Cohort r.rferienee Table 16 is the father marked .increase "in die .total numfurr of cases for the Province lietwren 195< and 1955. Ibis assumed that at Kras*, pirt of this Wrravr is due to "im ;*-ith that cf the PriK-ince.cf (Juehec. /*- proved revognitkm and rq*rtihg if lung hi info* cf Canada, and the CniieJ States -- cancer during the interval For this reason, In order to make a comjiarison of the the vear> 1954 and 1955 were thought to be -yxicriotK*e among asbestos miners with that more nearly representative f actual.condi-' of the general j*e>pukition of the Province of tions. F.ven . .-o. it is quite likely that the. OucIkv. statitio> were gathered, as stated general population is not'studied for lung earlier, in the office of the Division of cancer with the same diligence with which .1 i * Tstir.lft--C.'tnfjris.'n ,'/ teitk Pr.t-ii\ct nf Quebec .. . tTOTUK* T*t*I TToraJ rr>HK* rirlodm* lilaiio - ivna ' i.m.ooo* *.n>' 1.US.M * -tme .. HR ' a t m /. . iwt SD ' m t JU ' Luac Cuar rfaorhi 1*43 uea 1044 au jns am 3 t 31 au *00 am * IHi ar t XM . Aaauat Tout WfiQQ l**4 nt' ; t tsRt XU SJ CJ Is itw arurM. fa iw w*9 aO mlr lust (lom da*Ihi am far man at JO-1- yaw*. * AptmiiBau Bktpnur ayusaralaU pDputalBO far !:. aod lhaaa:reaa:<d pnrofatno far l*M .luppor-.. IVit a, fa Dr- "-<*rpfcir-. \uint*r ali ui tvlvar. a: twcaolM a( HAS. Hfiitm--Tnten _ - -6*5 * ..V x * * * t - v* * r" _ * . tbulOortiflod *: Vpaefflad Primary Tout Corttfiad; Sprctflod Prttoory.: Ay* Oracp ' so-u 4toM * 06-04 Totato . Fopulattoe - Tacal .fiortl .Toi 777400- amjob 1X7p00 uj/oo . `v-:- at * :.':vr u --:* . m m - 4> ..MB * SI . 00 ui aa . . ... .. 1437400- ' m \ _. t /' " *** fntol Tout - IT . - 00 aa 117 so 140 so 42 rw**d. Ttoiri *- 1too**d `V. k. i7 so'. - io V SJ im - * '* o* * . -a r ut ' . ut. `ua. ' -- ' ' [ JDeuk Koto* nr 100.000 ' * * ` ! >%* . ' 4 UM. v'Ittototpvttflod .. pretax! Pi lull y , *; 'ttU . . V * TCaJ Cortlflod SpoeUtod rrtmory in Qrocp V.,' -** .* Tout' j 40-04..___. m *0-04___________ -___ .714.' oi 4....----.--.---------.......--.... ota ... fwwl './Stottl . 4.* 1.4 ITS - S>4 W 00.4 sa - IU frovod 14 14.4 as.4 S4JD TM aa ao.T 4 tau J*rmr*d '.. Taut -_.Tr**d "174 S7.7 ?: 414 04.7 ' .444 . -ttl UJ 0t4 .444 *u. TJ. * IZi fix 11! CJ ,l?4 . -'v.v*.. > ' Data from daaxb eorrlWnito* * - -. . t grrlrnoto tor ponilolton ohwtwod by asplytac Wl pamotM** tor ** croup* for nuJrr to tbo total pnpohttoo lor 1004, * C>**s to Roppon, Dft. at to Drnocnpbto.. - 41 km this disease is looked for in the miners, and .* This amijiarison.summarized in Table ..it seems probable that the hx>rtality rates, .'18, ithow> that the' observed number of for the.. Prbvmre''niay Se.'loto;.. This'would`".deaths in uur sample is not significantly appear to be substantiated -by the Ifact .that- '.greater than the expected number of deaths, the importing of cases In the: cohort shelved based on the average of the 1954 and 1955 no such .increase'oveT the same'period- figures for the Province. It is true that, in Table 17 was compiled to show the an- <he case of the age group of 65 and over, nual age-specific lung cancer rate of cases the five deaths provide a figure which is in which.the death certificate merely read1 .. almost significant at the 95% level. - Hou - "c^cer of.the iimg^V as.disUnguished from ;. ever, it should be noted that this dumber those in which the diagnosis was confirmed ; includes one of the suspected but unproved by autopsy, surgery, or biopsy. The term cases previously referred to. Furthermore, `specified primary" refers to those cases iif. it .is rather likely that the rate for the these two categories in which the tumor was ` specified as haring originated in the lung. It .will be noted that, of the total cases reported in 1955, a much higher percentage general population is understated in this age group, for the obvious reason that the exact cause of death in the very old is not than in 1954 were specified as primary. The table also shows that a higher percentage of the total cases certified in 1955 were proved, again indicating increasing interest Tamlf 1f--Comparison of the Actual end Expected Number of Lump Cancer Deaths by Age Among Asbestos Miners in this disease. . : A comparison has .been .made* between the age-specific rates shown in Table 17, and those for the cohort, shown in Table 8. An average of the 1954 and 1955 rates for the Province has been used; since the 1955 figure was higher and may have been ex ceptional. .. Onus S*SO--4M4 Toul IpidM ObMTMd No. .Zrpeefed of Dootb* Frhnory KU No. of No. of - - - * per >00.000 Minor* PorUtf * rr**d Tout 14 X7.Je 1401 U* u aa t t. t ai ' aa j a : l ISOISUTootttoto-io-ipoponwedtitrkdmreen*mthoor ribtotbFatwodtKomo*thotf tmtr of Qaobac. th( 1004 n<1 t Actually 0.4. 646 I'ot. 17, June, tm  . -1 . , tV ' i .* <#_? _ m . " `yw-.y*.: :< -I ( Ac Qroop * KoBtar 7T7.UJ 1JM44 1U.4S7 usmm IVeaeUB M U N to Cebart ' H . H * < - MO .* >; ' I--Cropi Kapport, ItU. ' \j\- r.:~\r a matter of the same intensity of interest V* ; ~ TCM.T . as it is in younger persons. / : - V. A*. HJ -^>.>0714. *.-s : .. Table 18 also answers a . question' pre-' rSforuiUj'Svm Lot Cuar la Ckaafe,*; rk'Mis." viously raised. It shows that the members \ of the cohort have mot died from lung can increase , is particularly markedJaftef'/age * cer at an age earlier than the general popu-| .50, confi rming an observation . previously lation. and that such an explanation cannot;. made, to the effect that until recently lung be offered for the absence of lung cancer ? cancer has probablybeen underdiagnosed in 240 men writh more than 40 years of 'in the older age groups' in the"general popn- employment referred to on page * 1 v ..lation. ,*;J. Before leaving. this comparison [.of the^. :.^To .use .these, figures * tor ^purposes*-of . Province with the miners, it should be comparison, h is necessary -to; combine the shown that their age distributions arc rra- ' rates for certain agegfoups ^n'oirder to sonably the same. That this is the case can . conform to the age distributions tisedin this be observed from Table 19. study. Since the exact populations -in each . It should be remembered that the miners age group for the years indicated. b`not retire and consequently, it can be expected known, this must be an ' approximation. that the oldest age group will be larger in However, the rates would be .sprTWw-hat as the general population. The data presented follows: * :v;--. in Table 20 indicate that the lung cancer rate generally decreases after age 70. There fore, we could expect the rate for off people over 65 to be smaller than the rate for the A*t Creep' 20-44 4S-J4 Si-64 <5+ llK ' S' to - group between 65 and 75. which would apply .These fates are, in genei^/vWwer .ffun to the oldest group of miners. .'It is felt .those developed.for the total (proved'and that by using the whole adult male j*opula- ' suspected) cases'of lung cancer among the tion, we have developed rates for the gen eral population which arc somewhat lower than if we had been able to exclude the people in the general population over 75.. ,, A comparison between the asbestos miners and the population of the Dominion as a asbestos tniners. The only large difference, however, is in the age group of 65 years and over, and it is quite possible that the rate for this group may have increased for Canada between 1952 and 19S4..as-it did for the Province of Quebec'"(Tabie'I7). '' whole was made, using statistical material A further comparison has been made with from several sources. In one source, Phil an over-all fate obtained from the American lipsgave age- and scx-specific rates for Cancer Society for respiratory cancer deaths Canada for three jperiods between 1931 and in Canada in 1953. This rate, for males, 1952. The rates for males arc given in is 20.8 per 100,000, or 5 more per 100,000 Table 20. than Phillips' 1950-1952 rate, and compares These figures show strikingly the increase with 25.3 per 100,000 for proved cases and in rates between 1931 and 1952, and this 33.8 per 100,000 for total cases among the.' Braun--Truon 6t7 t K i  -r ' j , -. ,,: I' AfiOiM* ,' v TopdlBoV.#v ' ,- l; /'.. world, ana .it'"can -be assumed, that this. SM irHoaao number has been fairlyconstantln the 20 ^amunn iMOfiaa tjmjtn .aiw 4JH jJJ . years since 1935 when the, first rease of ,* . /- asbestosi* with lung cancer was reported. TUl UHM -jjj* ' At least 1,000,000. man-years of exposure. ' r has thus been accumulated, and'tKis figure * Dt* Iron **Vtu] SuUnko tt Oo VaUad Sum," VL 1 can tbe dividedb*y *,the approxi'mr~"a-~t d* y 1#5A0 'aettM*. cases of lung cancer wdth jasbestosis re asbestos miners in this study.- It is there ported' during the 20-year period." This fore obvious that' theire are no important gives a rate of 15 per 100,000, vAichJs at differences between .the rales for asbestos least indicative that any lung caricer^ ratc miners and those for the general population.^. which can be -calculated vlor'-- i' of Quebec and the Dominion of Canada.*- posed to asbestos dust is not much greater Since it is probable that figures for the. than that for the unexposed population. United States are more complete and, there-' Comparison Betnven Eight CounticsAd.fore, possibly more comparable to the data jaceht to the Asbestos-Producing Areas and for - Eight StUotod Count*,.-To lung . T"1 .nomlitj. rate in <hc cYnintfe's i.r-- ***. * > "< ; %*%?**.: m*Sm:t ` ^toslaye btro ukuUlcd .S ... .Wher gruu,. of couMies & wU'ct.' Wu: r rt> nppa^M tiui ?. w.0. fvorabb wlb.M^oMbe.sbCTtM mnnr. ^ ^ WsU iCSguris lor - as shown in' Table 8. Still other rates .for the year# 1950 through 1955; The eight -.the.United States were obtained from the counties selected for comparison were Ar- .American Cancer Society, arid for males, genleuil, Chateaugav, Monlmagny; '.Port- t_2h_8e_.s0e were 25.3 per pa- 100.000 u. 100,000 in 1953, J9u5. Thry .re -and - nHevuaf,cimlR*,icahnlideuT, rrVRrhivoinenret;-^dul-iLloyufpe,"'u:.S*t ' identical with the. rate'calculated from the they represent a .wide geographic distribu-' figures of the office of Vital 'Statistics, but tion throughout the Province. The counties this is possibly because the American. Can- selected because of their proximity tothe - cer Society rates are for males of all ages. Nevertheless, they, too,. compare favorably . asbestos mines'include Arthabaska/.Bearuce, - with the rates of 25 (or 34 for total cases) Drummond, * Frontenac, Megaritic, \Kich- obtaining among the, asbestos, miners; - r ..O mond. Sherbrooke, and Wolfe. Table 22 *. *. ' Turning for a nx^nent' to- a' comparison shows the number of lung cancer'deaths between the asbestos miners` arid persons -for the rears 1950 through 1955 for each * who are exposed to asbestos' in one form of these counties, and a mortality rate,. or another (as distinguished from the gen based or. ihe adult male population in 1952. eral population groups just discused, who To cm|thasize the comparison, Megantic have no. exposure) an interesting observa- Countt- has been shown separately, as has .V- ~*tion pan be developed bj deductioa.; Huc-. . the Province of Quebec arid alsothe^PrOVr.. per M his stated that fbere are about 35,000 ' ince with the eight ''`asbestos-producing" persons exposed in the United States, and counties subtracted. Because of its unique we have folmd that the Canadian mines lung cancer death rate, Montreal et Isle de \ employ about 8000. Elsewhere, it has been Jesus has also been listed in order to provide ; estimated that the workers in England who further comparison. ' . ' have exposure total between 3000 and 5000. It is apparent from the table' that the With workers in Africa, Denmark, Nor- lung cancer death rate for the eight counties ?* -A- - v w * - r , v . ' Vol. lfljw*, 195* =. - VvWr* . ,. V .. . CouMb* ' *. i*. A4oU M*b -------------------=----------------------------------------------------- - P.optmotuta - M0 /. MSI M % ns ISM wr ............ ToUT ,Slrcuitb Couiur Eifhi *'Ad)*amt Countir* EUOit fbeu4 Ceonlfet prorloce of Uuoboe Prorinot of Quebte b tfebt *'odtorrol " OOQUtWO Slontml el lib 4t Smut \ -WU1.SMODD svono - i,nun ' * * I.M0JB0O aouno wa no S, 1. H9 tao swT 1 ' * * < .. it S l SU SM ' -.1*7 M* .m -' ' i L >t v: 41 . SOI n 04 'M*7 ' .40 MM a IU . Ml trio : ;: 'po . siiTC' 0.4 .. *A . - ' . *.*. 'll b Mamed ituioOnwb hjntouiorr 4csi! occurr<t oftor act V immediate!)' surrounding the asbestos-pro ducing areas is practically identical With that of eight counties selected for comparison. While Megantic County has a rate nearly twice that of the combined eight selected counties, it is lower than the rate, for the Province, and considerably lower than the rate for Montreal. The figure for Montreal would certainly be higher except for . the very low numbers of deaths reported for 1950 and 1951,. and it would appear that in those years some error in reporting has undoubtedly been made. On the basis of the other, years, 1950 and 1951 deaths would be exjiectcd to .be about 200 greater. This would result in a rate of 40 per 100,000. . The only possible conclusion from this comparison is that there is no evidence that the persons who live and work in the coun ties surrounding and adjacent to the as bestos-producing areas have any greater incidence of lung cancer than those who live elsewhere in the Province. Comment on All Recorded .Lung Cancer Cases, Living and Dead, among the Asbes tos Miners.--Although a simple enumera tion of all the known or suspected cases of cancer of the lung in these areas has no ]<articular value from a statistical point of view, it is of interest to summarize such cases for the record. There were nine deaths prior to the beginning of the time period covered by the study, including one in which the diagnosis was mediastinal lymphosar coma. During the period covered by this investigation, there were nine proved cases and three suspected cases in the cohort. Through 1956 and to la(e in 1957, there were eight deaths, six of which were merely suggestive" of cancer of;-the. Jung ind, in-; eluded such diagnose s'7as "jriedlastinal 'lymphosarcoma, mesotheliomacancer of the leg with metastases to lung' abscess of lung, and cancer of the p^creas. C)iie other yens diagnosed on the basis of x-ray ~only.'rIn addition, there are now living four, cases in which. the diagnostic evidence is^stipngiy suggestive of lung eanoer^ThUjValt^] of: 33 cases of all types, ineludjrtglO ^sus pected" but unproved cases, and 4 that are' still living. The remaining' 19. cbnidtute the. total of proved ids''o'f canw among the asbestos miners since The proved cases averaged 59 years of age at death, and varied between 37 years and 68 years. Their workingspan covered periods trying from a minimum years to a maximum of *37 years. 7 Only three men had less than 25 years [of em ployment in the industry. Se\Tn >ambng those on whom such mformatidn .is'avail-' able had a weighted exposure placing them- only 17 among these'proved lung cancer cases in which we have in formation regarding. the . presence of as- bestosis. Asbestosis was present in nine, although it was minimal in two. Two path-.* ologists disagreed regarding its presence 3n another. At least seven of the 19 proved lung cancers, therefore, were not accom panied by aslfcstosis. "*"i Summary and Conclusions Interest in the question of whether there may be an association between lung: cancer Y `* * .y*\ ( (I ana exposure_TO asDeuos nas oecn eviacnv , nw nor.: rf sincethereport in 1935 by Lynch and Smith'-'/the wholejirK^fatv of a case in which lurgcancer and b- '5958 werc'fouod^tb'be stjlj^bvfcgjnt^SS; tosiswereboth present' Asadditional`cases or later. Of fl>e 187 Imdwij .dead^cer in which the two diseases coexisted were of the iting was considCT^._^^ve^l>e>!m reported, a causal association appears to * reasonably proved in.9 andji^be-Sroiigiy have been y gradually accepted by many suggested in 3.. > v: authors, although some workers considered The members of the* cohorCiwere studied : , the correlation to be inconclusive. The pres- with respect to age, length of, employment, . ent study was undertaken in an effort to de a weighted average of theirjpcposure,' and termine whether a causal relationship did, their smoking'habits..' li was* fpund. that in fact, exist between exposure to asbestos 4673 were smokers within the '.definition!of and cancer of the lung. that term as used in this sfudy./. ThirtyTfour . Since* most earlier studies had been per cent of the d^rt w^e^nwre ihan 45 . limited to enumerating the lung cancers years "of age, and thirty per/cent, had .been' - found in .certain selected samples,' such as employed for longer than 20 years.-Thirtv cases coming to autopsy or death certificates per cent had a weighted-exposure' which m which asbestos!* was mentioned, it was placed them in the calegoty of highest ex apparent that they could not fulfill the re quirements of an epidemiological and sta tistical approach -to the' '`problem. The present study was, therefore, . designed to meet the rjuirements of Ous method. . . After a .preliminary survey to explore 'Jbe. availability of reliable .^information, * 'data pos0"- . . v The mortality .rale .for lung''-cancer,- as computed on the .basis of ihine ^jiroyed" deaths among the cohort was'25-3 per ;jOQ,- ;, . 000. When the three *`su.pected}?caiiei were . added, the *4tntal*'.'nate for lhe cohoil'jrose lo 33^ Th* importance of the Suspected were gathered on workers in the'asbestos * ^ unprovr(i ses in det^hming these' mines in Quebec, based-on* their medical rates has been reiterfled because it.Is likely records. A cohort was defined as a group that such cases would not'T)6 inauded iih of asbestos miners having at least' five year, j;. thc statistics fi>f the gOTerijipulatVon - and : * fotf exposure *an"*d ^who were in Athe* >innd/ufnsctfrfyv because they influence the rewilts^rmii^ . in 1950. Data relative to their characteristics were collected and their stetus at the end :-;-r ': .:r : According to the"findings rnlhis study, - of a six-year period of observation was de^ the .'mortality rate from King"cancer -does ;; termined. In the case of' those w:ho had not appear to increase with'length of ex- died, an exhaustive search of death certif posure or with degree of exposure, a fact icates arid insurance records was carried out which presents strong evidence against the ' in order to determine as nearly as possible carcinogenicity' of asbestos., i lv'v1- ' ` the exact cause of death.. Mortality rales Comparison of the experience among the from lung cancer for the general population asbestos miners with that of various seg of the Province of Quebec and its various ments of the unexposed, comparable popu counties and . for the Dominion of Canada, lation sliows that the observed, number of as well as the United States were calculated deaths among the miners. is'iwt aighificinUy from statistics collected in' the appropriate greater than the expected nomkfr. ^Therate ' places. Comparisons of the rates obtained for proved cases among the asbestos miners for asbestos workers and for the other popu (25.3 per 100,000) compares'well With the lation groups, were made according to ac rate of 22.5 per 100,000 for the rest of'the cepted statistical methods. Province, and 20.8 per 100,000 . for adult Records were obtained on 6091 persons males throughout the Dominion of Canada. who fulfilled the criteria of the cohort. It It also compares satisfactorily with rates t 650 : 1959 w>A* * 9.\m I V^;v *, ( sources for aduliflt males ia'tbe United Statji ?****: Finally, in this natter of poenparison,- it , would appear that the world-wide experience of persons exposed to asbestos dust is not worse with respect to lung cancer than that of the unexposed population! ' >; The counties surrounding the asbestos- producing areas, in which it is presumed most of the asbestos miners live, have'al fcerufskraakk 45 t^dOJU^i5)iTl^S*&& .&. f. BerbJinger, W.: locreaae/jDf Jjmg' Cancer" -*' sad Disease* Due to Dust lohalation, Med.^JC&a Z7;U37-1342 (Se*.ll) 9. Bercobtum, L: Irritatioe and Carcro - Arch Pith 38 :23J-244 (Oct.) SO. Bohne\*Asbestosis,'Deutsche raed." most identical morality rates with those eight counties widdy scattered through Province, and art lower than those for-the remainder of the Province, and much lower than the rate for .Montreal. Since 1940 there have been 19 cases in which the diagnosis of primary cancer of the lung may be considered to have been proved. Approximately half of these cases SHikose 12. Bowies, and Fabrication, Information QradarNoi-6869,> u. s. " 'Department of the latmor;?--B-u-r-eau*->f Mines, IMS, ip. i ji: -12. B*res'low, *L.; HHaaaagtgint,i*n^,L'L.; TRJbausmoussecan,""GGuu, aeid Abrami, H. JC.: Occupations and .'Cigarette V . Smoking at Factors;s. in "Lung' 'Carv^ were associated whh asbestosis: All but one died in the recognized "cancer-age" and least one-third had only the lightest ex- _ S__il_ic_o_s_i_s and -Aibe*tosts,"A- M. AJ' Aoh. Indasf posure (Category IV to asbestos dust.. Health . ,, 15.`Cancer]6f the Lung: * ~ *- 1 On the lasts'of what are heheved to he Prwedin^ of the' complete and reliable data, it seems fair to Annual Meeting, American .; conclude that the asbestos miners in the . Nor. 2-4, 1952, New Yorlc, American Cancer,'- 7^. Province of Quebec do not have a s-ignif* Society. Inc, 3956.V^7'' icantly higher death rate from lung cancer * 16. Cartier, P.t Asbestosis than do comparable segments of the general - " discussion ion Smith, W. E: SnrveyTol Stine - - ]<opulation.-7 ; Furthermore, the death rate from lung cancer in the areas' contiguous to the asbes- Current British and European Studies.'of Occupa tional Tumor, Problems, A. M. A.' Arch. ~ladasL Hyg. 5:262-263. 17. 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