The Health Consequences of SMOKING A PUBLIC HEALTH SERVICE REVIEW : 1967 U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE i, &, Public Health Service Public Health Service Publication No. 1696 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20802 - Price 60 cents Foreword The Federal Cigarette Labeling and Advertising Act of 1965 (Pub- lic Law 89-92) requires that the Secretary of Health, Education, and Welfare submit regular reports to the Congress on the health conse- quences of smoking, together with any legislative recommendations he may wish to make. € This 1967 Surgeon General’s Report was prepared to provide the Secretary and the public with a review of the research findings which have taken place in smoking and health in the approximately 314 years which have elapsed since the Surgeon General’s Advisory Committee issued its monumental 1964 report. Part I of this document was in- cluded as part of the Secretary’s 1967 Report which he sent to Congress in July 1967. Part II, which provides detailed discussions of the re- lationship of smoking to specific diseases, is issued here for the first time. The 1967 report represents a review of more than 2,000 research studies published since the 1964 report. These additional studies con- firm and strengthen the conclusion of the Surgeon General’s Advisory Committee that: “Cigarette smoking is a health hazard of sufficient importance in the United States to warrant appropriate remedial action.” In a separate section of this report, acknowledgments have been made for the help of numerous scientists both within and outside the Public Health Service, who participated in the preparation of this report. These include the 10 distinguished scientists who made up the Surgeon General’s 1964 Advisory Committee, all of whom were kind enough to review part I of the 1967 report before its publication. A special word of thanks is due Leonard M. Schuman, M.D., one of the 1964. committee members, who advised the staff in the final editing of the entire document. SURGEON GENERAL. Table of Contents Introduction__-_------------------------------ Smoking and Overall Mortality ---------------- Some General Considerations - - ------------ Smoking and Overall Morbidity--.------------- Smoking and Cardiovascular Diseases. -- ------ Smoking and Chronic Bronchopulmonary Dis- eases (Non-neoplastic) - --------------------- Smoking and Cancer-.------------------------ Other Conditions and Areas of Research. - ------ Cited References- .--------------------------- II. Technical Reports on the Relationship of Smoking to Specific Disease Categories---------------------+ Chapter 1. Smoking and Cardiovascular Diseases_ 2. Smoking and Chronic Bronchopul- monary Diseases (Non-neoplastic) . 3. Smoking and Cancer- -------------- 4. Other Conditions and Areas of Re- Acknowledgments Responsible for the preparation of this report was the National Clearinghouse for Smoking and Health, Daniel Horn, Ph. D., director. Staff director for this report was Albert C. Kolbye, Jr., M.D., M.P.H., LL.B. The professional staff has had the assistance and advice of a number of experts in the scientific and technical fields in and outside govern- ment. The staff gratefully acknowledges their contributions, often made at considerable sacrifice of time from their own professional duties. Although space does not permit a listing of all those who have participated in this project, the staff wishes to express appreciation for their cooperation and help. Special thanks are due the following: ABINANTI, Francis R., D.V.M., Po. D.—Chief, Virology and Rickettsiology Branch, Extramural Program, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Md. AMES, Bruce N., M.D.—Laboratory of Molecular Biology, National Institutes of Health, Bethesda, Md. AREND, WitLt1amM P., M.D.—Medical consultant, Stroke Section, Heart Disease Control Program, National Center for Chronic Disease Control, U.S.P.HLS., Arlington, Va. AUERBACH, Oscak, M.D.—Senior medical investigator, Veterans Administration Hospital, East Orange, N.J. AxELEop, Davin, M.D.—-Medical consultant, Laboratory of Biology of Viruses, National Institutes of Health, Bethesda, Md. Ayes, SrepHen M., M.D.—Director, Cardiopulmonary Laboratory, Saint Vin- cent’s Hospital and Medical Center of New York, New York, N.Y. Ayres, WILLIAM R., M.D.—Medical officer, Heart Disease Control Program, Na- tional Center for Chronic Disease Control, U.S.P.H.S., Arlington, Va. BALLENGER, JOHN J., M.D.—Head, Department of Otolaryngology, Evanston Hos- pital, Evanston, IL Berenpes, Hernz, W., M.D.—Chief, National Institute of Neurological Diseases and Blindness, Perinatal Research Branch, National Institutes of Health, Bethesda, Md. Bere, Gorpon W.—Statistician, Operational Studies Section, Cancer Control Pro- gram, National Center for Chronic Disease Control, U.S.P.ELS., Arlington, Va. Ber.ines, Ropeer, M.D.—Director, Office of Director of Research, National Heart Institute, National Institutes of Health, Bethesda, Md. Bine, Ricuarp J., M.D.—Professor and chairman, Department of Medicine, Wayne State University, Detroit, Mich. Bress, Stuart R., M.D.—Medical consultant, Heart Disease Control Program, National Center for Chronic Disease Control, U.S.P.H.S., Arlington, Va. Boren, Horzis, M.D.—-Clinical investigator, Veterans Administration Hospital, Denver, Colo. : . Carrot, BENJAMIN E.—Biometric Branch, National Cancer Institute, National Institutes of Health, Bethesda, Md. CHADWICK, DonaLD R., M.D.—Director, National Center for Chronic Disease Control, U.S.P.H.S., Arlington, Va. DE LA PUENTE, JosePH L.—Chief, statistical methods, Cancer Control Program, National Center for Chronic Disease Control, U.S.P.H.S., Arlington, Va. Deyxin, DANIEL, M.D.—Assistant professor of medicine, Harvard Medical School, Boston, Mass. Dozss, GeoraE, M.D.—-Associate chief, Division of Scientific Opinions, Federal Trade Commission, Washington, D.C. Doytrsz, JosrrH, M.D.—Director, Cardiovascular Health Center, Albany Medical College, Union University, Albany, N.Y. HastTMan, Nicotas J., M.D.—Professor emeritus of obstetrics, Johns Hopkins Hospital, Woman’s Clinic, Baltimore, Md. Eprstemn, Freperick H., M.D.—-Professor, University of Michigan School of Public Health, Department of Epidemiology, Ann Arbor, Mich. Exzicu, 8S. Paut, Jr., M.D.—Deputy chief, Heart Disease Control Program, Na- tional Center for Chronic Disease Control, U.S.P.H.S., Arlington, Va. Evans, Rogert, Ph. D.—-Department of Sociology, University of Wisconsin, Madison, Wis. Fax, Hans L., Ph. D.—Associate scientific director for carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, Md. Ferris, BENJAMIN G., Jr., M.D.—Professor, Department of Physiology, Harvard School of Public Health, Harvard University, Boston, Mass. Fox, Bernarp H., Ph. D.—Acting Chief, Experimental Research Branch, Injury Control Program, National Center for Urban and Industrial Health, U.S.P.HLS., Arlington, Va. Fox, Samvuszt M., III., M.D.—Chief, Heart Disease Control Program, National Center for Chronic Disease Control, U.S.P.HLS., Arlington, Va. . GITTLEsOoHN, ALLAN, Ph. D.—Professor, Johns Hopkins School of Public Health and Hygiene, Johns Hopkins University, Baltimore, Md. Gop, Ronatp J.—Statistician, Operational Studies Section, Cancer Control Pro- gram, National Center for Chronic Disease Control, U.S.P.HLS., Arlington, Va. HaENszEL, WILLIAM M.—Chief, Biometry Branch, National Cancer Institute, National Institutes of Health, Bethesda, Md. HAprrin, Max, Ph. D.—Assistant chief, Biometrics Research Branch, National Institutes of Health, Bethesda, Md. Hammonp, E. Cuyter, Sc. D.—Vice president, epidemiology and statistical re- search, American Cancer Society, New York, N.Y. HaskeEL., WirrxzaM L., Ph. D.—Physical activity consultant, Heart Disease Con- trol Program, National Center for Chronic Disease Control, U.S.P.H.S., Ariing- ton, Va. Hayes, Ricrarp, D.D.S.—Assistant to the chief, cancer detection, Cancer Control Program, National Center for Chronic Disease Control, U.S.P.H.S., Arling- ton, Va. HEINZELMAN, FRep, Ph. D.—Research psychologist, Heart Disease Control Pro- gram, Natfonal Center for Chronic Disease Control, U.S.P.H.S., Arlington, Va. Hess, CATHERINE B., M.D.—Assistant to the chief, Cancer Control Program, Na- tional Center for Chronic Disease Control, U.S.P,H.S., Arlington, Va. Hicorns, I. I. T., M.D.—Professor, University of Michigan School of Public Health, Department of Epidemiology, Ann Arbor, Mich. HorrMaNn, Dieteton, M.D.—Associate member, environmental carcinogenesis, Sloan-Kettering Institute for Cancer Research, New York, N.Y. , Imsoven, C. A., Jr., M.D.—Chief, Chronic Respiratory Disease Control Program, National Center for Chronic Disease Control, U.S.P.H.S., Arlington, Va. IsxRant, AtsmrT P.—Chief, Epidemiclogy and Surveillance Branch, Injury Control Program, National Center for Urban and Industrial Health, U.8.P.EL8., Arlington, Va. KANNEL, WILLIAM B., M.D.— Associate medical director, National Heart Institute, Harvard Medical School, Boston, Mass. Kenner, Hargis, M.D.—Medical consultant, Heart Disease Control Program, National Center for Chronic Disease Control, U.S.P.H.S8., Arlington, Va. Ko.syE, Susannan M.—Scientist, Chevy Chase, Md. Korin, Pavt, M.D.—Director, National Environmental Health Sciences Center, Research Triangle Park, N.C. Kevunorr, Dean B.—Statistician, Biometrics Section, National Heart Institute, National Institutes of Health, Bethesda, Md. LANDAU, EMANUEL, Ph. D.—Statistical advisor, Office of the Director, National Center for Air Pollution Control, U.S.P.H.S., Washington, D.C. Lecator, Marvin S., M.D.-—Chief, Cell Biology Branch, Division of Nutrition, Food and Drug Administration, Washington, D.C. LeMaIsTrE, CHaRLes A., M.D.—vVice chancellor of health affairs, Office of the _ Chancellor, University of Texas, Austin, Tex. LILIENFELD, ABRAHAM, M.D.—Professor, Johns Hopkins School of Hygiene and Public Health, Baltimore, Md. Loncrn, Huseet, M.D.—Office of associate director for collaborative studies, National Heart Institute, National Institutes of Health, Bethesda, Md. Loupon, R. G., M.D.—Professor, Department of Internal Medicine, University of Texas, Dallas, Tex. : MaRLAND, Riowarp E., Ph. D.—Injury Control Program, National Center for Urban and Industrial Health, U.S.P.H.S., Arlington, Va. MoLean, Ross, M.D.—Professor of medicine (pulmonary disease), Emory Uni- versity, School of Medicine, Atlanta, Ga. Morrison, BayagD H., Ph. D.—Office of the Director, National Cancer Institute, National Institutes of Health, Bethesda, Md. Mount, Frank W., M.D.—Deputy chief, Ohronic Respiratory Disease Control Program, U.S.P.H.S., Arlington, Va. Morpuy, EpMonp A., M.D.— Associate professor, University of Colorado Medical Center, medicine and biostatistics, Denver, Colo. PETERSON, WILLIAM F., M.D.—Chief, Obstetrics and Gynecology Service, USAF Hospital Andrews, MSHCB, Andrews Air Force Base, Washington, D.C. Petty, THomas L., M.D.—Assistant professor of medicine, University of Colo- rado Medical Center, Denver, Colo. Rosrns, Morton—Chief, program evaluation and project design, Heart Disease Control Program, National Center for Chronic Disease Control, U.S.P.ELS., Arlington, Va. Ross, Wittzam L., M.D.—Chief, Cancer Control Program, National Center for Chronic Disease Control, U.S.P.H.S., Arlington, Va. ScuuMan, Leonagp M., M.D.—Professor of epidemiology, University of Minne- sota, School of Public Health, Minneapolis, Minn. Scuwartz, J. Tueoporr, M.D.—Section head, Epidemiology Branch, National Institute of Neurological Diseases and Blindness, National Institutes of Health, Bethesda, Md. Suear, Murray J., Ph. D.—Special advisor, Office of the Director, National Cancer Institute, National Institutes of Health, Bethesda, Md. Smwe1, James 8S., M.D.—Chief, Field Staff, Coordination and Development Section, Heart Disease Control Program, National Center for Chronic Disease Control, U.S.P.H.S., Arlington, Va. ; STEINKE, Wirt1am, M.D.—Medical officer, Heart Disease Control Program, Na- tional Center for Chronic Disease Control, U.S.P.H.S., Arlington, Va. Srxone, Jack, M.D.—Chairman of Department of Pathology, Louisiana State University, School of Medicine, New Orleans, La. Tom, THomas J.—Statistician, Heart Disease Control Program, National Center for Chronic Disease Control, U.S.P.H.S., Arlington, Va. UNpERWoop, Paul, M.D.—— g 3 °o I COHORT OF PERIOD OF MALES BIRTH = ° a o NUMBER OF DEATHS PER 100,000 POPULATION » a AOS -1079 -Betore 1875 I | J | ! I ! I I | 40 “4 so 58 60 8 To ws 80 aSene AGE IN YEARS 4000 60.0 200 109 eo 60 40 20 oe oe oe Os Fieurg 1.—Cancer of the lung among men, by birth cohort and age at death; 1949, 1954, 1959, and 1964. eT aainog . (76) BIASHBIP DBI JOJ J9}UVH [BUONEN NUMBER OF DEATHS PER 100,000 POPULATION 1000 1000 800 }— 800 600 600 409 400 200 —200 100 109 sok COWORT OF PERIOD OF leo FEMALES BIRTH of | 6 oI 925=182B 60 1920-1924 4or- 1915-1919 —40 1910-1914 1908-1909 20 .. 1900-1904 20 1895-1899 onuenee es 1BBO= 1894 10 1885-1889 10 oe fh a rn 1aao- 1884 oa ost . 1875-1879 tos De ceeceesenecs reteset - Before 1075 on os az oz ou l 1 | | l l ! | | Ol 20 45 30 38 60 6s 70 75 80 AGE IN YEARS @5 ond over Fucure 2.—Cancer of the lung among women, by birth cohort and age at death: 1949, 1954, 1959, and 1964. In the female population the greatest percentage increase (116 per- cent) over the 15-year period, 1949-64, occurred in the 35-44 year age group. The next highest percentage increase was noted in the age group 45-54 years. The death rate from lung cancer among women, 25 years and over, rose steadily with advance in age for each year during 1950-64, and the cohort experience shows that these death rates continued to increase for each cohort to the end of the life span. Hammond’s (40) prospective study provides extensive information about the lung cancer mortality experience of both men and women in relation to cigarette-smoking history as presented by mortality ratio? and by death rates per 100,000 person-years. (Table 1). TasLe 1.—Lung cancer mortality ratios and death rates * of smokers by sex and specific age groups 45-64 years 65-79 years Females Males Females Males Mortality ratios____........__- 2.17 7. 84 11. 76 11. 59 Death rates_.._.-..---- 22-2 e 2(7)15 | 2 (11)87 | 2(17)30] 2 (23)262 1 Computed from app. table 19. 2 Numbers in parentheses indicate death rate for nonsmokers. Sourcr: Hammond, E. C. (tables 24 and 26, app. table 19 (40). Tables 2 and 3 below show the relationships of number of cigarettes smoked per day, degree of inhalation, and age smoking began, to lung cancer mortality ratios and death rates for males and females, respectively. Generally, mortality ratios and death rates increase with increasing amount of cigarettes smoked and degree of inhalation, and with a longer lifetime history of smoking. Table 3 shows the relatively lower lung cancer mortality among women as contrasted to men, but reveals, for the most part, the same relationship to amount smoked, degree of inhalation, and age when smoking began. Table 4 illustrates the fact that cessation of cigarette smoking is associated with a decline in lung cancer death rates. * The mortality ratio is the ratio of the death rate of smokers to that of non- smokers—the mortality ratio of nonsmokers always being one, by definition. 134 TABLE 2. —Lung cancer (men). Number of deaths, and age-standardized death rates and mortality ratios, by current number of cigarettes smoked per day, degree of inhalation, and age began smoking, by age at start of study * Age 35-54 Age 55-60 Age 70-84 All ages, 35-84 Number of cigarettes a day, degree of inhalation, and age began smoking Num- | Death | Num- | Death | Num- | Death | Num- Death ber of | rate | berof| rate | berof] rate { ber of | rate deaths deaths deaths deaths Current number of cigarettes a day: 9 38 12 ci] 5 134 26 56 15 4 &7 168 10 23 82 90 138 88 216 204 27 446 381 159 26 47 50 334 6 754 82 201 Degree of jnhalation: None or slight... -----.----------- 19 2 87 203 4 193 120 102 114 52 17 224 20 401 311 138 Deop-..------------0-------2---- 55 55 3 206 13 63s wi 178 Age began cigarette smoking: 25 or older. 5 7 12 65 3 85 20 30 20 to 24... 31 36 72 212 7 306 110 118 15 to 19.-.- 112 4 176 250 2 490 318 155 Less than 15. 35 n 87 302 9 424 101 183 Never smoked regularly. i 6 a 10 u 25 49 12 Lung cancer mortality ratios (men) Current number of cigarettes a day: 1 tO 9.-- 2 nnn n ee een ne nen nne en nee eee 6.17 |.....--- 3. 53 5.32 4.60 10 to 19. - -- 3.90 -| 8.77 9. 62 7.48 20 to 30._...---.-------- +--+ --- | ---- => 9.37 -| 13.82 -| 17.62 13.14 40 plus ....---.------------------]----2 2° 7.67 |_.---.-- 17.47 }..------ 20.84 |..----.. 16. 61 Degree of inhalation: None or slight. 4.75 |.------- 10, 60 }..------ 7.65 |-------- 8,42 Moderate_....--- 8.48 -| 11.72 15.88 11.45 Deep.....----------------------- 9.00 13.93 25.26 j_.----- 14.31 Age began cigarette smoking: 25 or older. 2.77 3.39 j-.------ 3.38 |-------- 3.21 20 to 4... 11.11 ~} 12,11 J-_.----- 9.72 15 to 19._--..--..------ 13. 06 19.37 -| 12.81 Less than 15...---.------------ 15.81 {--..---- 16.76 |..-.-.-- 15.10 1 Mortality ratios are based on death rates carried out to 1 more significant figure than shown. Source: Hammond, E. C. {table 20 (40)]. 271-394 O—67——10 185 TABLE 3.—Lung cancer (women). Number of deaths, age-standardized death rates, and mortality ratios, by type of smoking (lifetime history), current number of cigarettes smoked per day, degree of inhalation, and age began smoking, by age at start of study } Age 40-54 Age 55-74 All ages, 40-74 Type of smoking (lifetime history) Number | Death | Number| Death | Number/ Death of rate of rate ot rate deaths deaths deaths 25 4 77 12 102 7 48 u 3 23 81 16 Current regular cigarette smoking 15 8 5 7 20 8 2B 7 2 50 50 35 16 13 9 18 2 13 7 i 18 48 45 2 7 6 16 21 23 2 35 14 i 43 46 7 Lung cancer mortality ratios (women) Never smoked regularly... 1.00 |-......... 1.00 [.......--. 1.00 History of cigarette smokin: 2.82 jee. 1.08 [.......... 2.20 Current regular cigarette smoking 2.08 [-....----. 0.62 |.---...... 1.06 4.43 |. 2222. 4.91 |..-..-.-.. 4% 3.33 1.12 178 2.90 4.04 3.70 1.55 1% 1.70 3.78 3.60 3.65 1 Mortality ratios are based on death rates carried out to 1 more significant figure than shown. Source: Hammond, E. C. [table 23 (40)]. 186 TABLE 4. tality ratios for ex-cig only, by former numb last cigarette smoking. Death a history of cigarette smoking only. Men are shown for comparison. Men aged 50-69. —Lwung cancer (men). Age-standardized death rates and mor- arette smokers with a history of cigarette smoking er of cigarettes smoked per day, and years since rates for current cigarette smokers with who never smoked regularly Smoked 1-19 cigarettes aday | Smoked 20+ cigarettesaday Mortality ratio, cigarette smokers (years eee last cigarette smoking) Number | Number| Death | Number | Number Death | 1-19 2+ of men | ofdeaths} rate | of men | of deaths rate 7468 3 108 2, 244 3 487 |_.--.---|-------- 1,844 5 cc") 5, 435 33 190 |......--|-------- 1,770 1 15 5, 803 22 108 |__..-.--|-------- 4,209 1 6 8, 142 5 16 j.---.---|-------- Total ex-smokers. -..-- 8, 569 10 30 21, 624 8 119 12.0 7.9 Current cigarette smokers...) 22, 808 80 97 56, 886 351 205 6.5 13.7 Never smoked regularly--..- 55, 728 32 15 55, 728 32 15 }..------|-------- 1 Computed from source. Source: Hammond, E. C. [table 21 (40). The Dorn study (49) of U.S. veterans provides additional informa- tion on the relationship of dosage to mortality ratios and death rates for males who smoked cigarettes only (table 5). TABLE 5.—Lung cancer mortality ratios and death rates for U.S. veterans by age, type, and amount of smoking Number of cigarettes/day 0 19 10-20 21-39 40+- pr'| mri |pR| MR |DR| MR |DR/} MR | DR; MR Current cigarette smokers only: Age 45 to $4_....---..----|------|--------|---2--| eee eee 24 52 72 |._.----- Age 55 to @4.___....-----. 10 1.00 70 7.00} 123 | 12.30! 206) 20.501 338 33.80 Age 65 to 74.._.--...----- 30 1.00} 135 4,50 | 265 8.83] 432 | 14.40] 696 23.20 Age 75 plus. 1.00 |-...-- Total. ---....-----.---- 1.00 j.--.-. 5.49 9.91 17,41 23.93 Ex-cigarette smokers only...-|.-----|--------]------ 95 248 9.33 |_..... 8. 24 1 DR, Death rate; MR, Mortality ratio. Source: U.S. veterans study [app. table A (49)]. 187 The mortality ratios of the Dorn (49) study can be compared with those of the Canadian veterans study, in table 6: TaBLe 6.—Lung cancer mortality ratios for Canadian veterans by age, type, and amount of smoking Number of cigarettes/day 0 | 1-9 10-20 214 Current cigarette smokers only: Age 30 to 49... 22-2 1. 00 2. 47 4.15 4. 08 Age 50 to 69__._--_----- ee 1. 00 10. 71 26. 92 26. 83 Age 70 plus____-_.__---...----.-_- 100] 12.15 9. 43 24, 53 Total__..---2 ee 1 00 10. 00 16. 41 17. 31 Ex-cigarette smokers only total_.____.__- 6. 06 Source: Canadian Pensioners study [(8), Table 8.1 and 8.2]. From the data shown in table 2 mortality ratios of 17.47 and 29.84 may be noted for smokers of 40+ cigarettes per day, age 55-69 and 70-84, respectively. The Dorn (49) study (see table 5) similarly shows mortality ratios of 33.80 and 23.20 for smokers of 40+ cigarettes per day, age 55-64 and 65-74, respectively. The Canadian study (see table 6) shows mortality ratios of 26.83 and 24.53 for smokers 50-69 and 70 years of age and older respectively who smoked over 20 cigarettes per day. There is rather close agreement among the three large prospec- tive studies for the general range of mortality ratios observed in heavy smokers. From the data supplied by the Doll and Hill survey of British physicians (28, 29) a mortality ratio of 31.86 can be calcu- lated for all smokers of more than 25 cigarettes per day, as com- pared to a mortality ratio of approximately 8, for smokers of 1-14 cigarettes per day (see table 8). There is relatively little risk of lung cancer associated with pipe or cigar smoking, probably because smoke from these sources is rarely inhaled. “Mixed smokers,” i.e., smokers of cigarettes, pipes, and/or cigars, have less risk than do smokers of cigarettes only, also suggest- ing that they may smoke fewer cigarettes or inhale less tobacco smoke than do smokers of cigarettes only (see tables 7 and 8). 138 TABLE 7.—Lung cancer mortality ratios by type and amount smoked Current smokers of cigarettes only pipe andjor Exemokers of Allamounts 1-9 10-20 21-39 40+ nipe and{o ¥ per day 12. 14 5, 49 9. 91 17, 41 23, 93 1 67 5. 00 Source: U.S. veterans study (app. table A (49)]. TABLE 8.—Lung cancer death rates by type of smoker and amount smoked Cigarette smokers An —| Given up | Mima | Pipe or Nonsmokers | SMoKets |, mounts| 1-14 | 15-24 | 25+ | smoking per day : 7 71 120 57 129 223 24 52 43 Source: Study of British physicians [tables 23 and 24 (28)). Taste 9.—Lung cancer death rates for ex-smokers of cigarettes by length of time stopped smoking Continuing Ex-amokers cigarette Nonsmokers smokers Less than 5 years 5-9 years 10-19 years 20-+- years 128 67 49 18 19 7 SouRcE: Study of British Physicians {table 25 (28)}. The preceding studies show appreciably lower mortality ratios and death rates from lung cancer with the cessation of cigarette smoking (see tables 4, 5, 6, 7, 8, 9). This lower risk is evident irrespective of the quantity of cigarettes formerly smoked. The Doll and Hill study (28) of British physicians is of particular interest in respect to ex-smokers. Over the 10-year period of the study (1951-61) 29 percent of the smokers of cigarettes only, had signifi- cantly decreased (one-half pack cigarettes or more) their smoking (in- cluding those who stopped) and 5 percent had switched to pipes and/or cigars. While the overall lung cancer mortality of men over age 25 in England and Wales had increased 22 percent over this 10-year period, that for the physician group decreased 7 percent. Since the total physician group is involved in these figures, we can compare this population group to the entire population of England and Wales where there was no general decrease in amount of smoking. This can be thought of as a controlled cessation experiment and the beneficial 139 effects of stopping or decreasing the amount of smoking become quite evident. Wicken (102), in a retrospective study of lung cancer mortality in Northern Ireland during the period 1960-62, reported the following results (Table 10) : . TaBLE 10.—Lung cancer mortality ratios and death rates, by sex, age 36 and over, by type and amount of smoking, Northern Ireland, 1960-62 Cigarette smokers Non- amount per day Cigarettes | Pipe and smokers and pipe | cigar only and cigar 1-10 11-22 | 238+ Male: Mortality ratios_.______ 1,00 | 483 | 9.33 | 21.2 5, 22 2.27 Death rates_._._.__.___ 18 87; 168) 383 94 41 Female: Mortality ratios. _._____ 1.00 | 2.27) 6 72) 19.0 ].-_-.._}L Death rates..___-_______ 11 25 74 | 210 |... ote SouxcE: Wicken, A. J. ((108), Table 17). Wicken also analyzed the proportion of lung cancer deaths which would have occurred if the lung cancer mortality rates of the least susceptible groups had been applied to the whole population of North- ern Ireland, and found that. males would have had only 18 percent of the lung cancer mortality if none smoked and that if they lived in truly rural areas they would have only 10 percent of the mortality. Thus, the difference—8 percent—may be attributable to the urban or suburban residence factor, possibly air pollution. If no females smoked, they would have had only 65 percent of the total female lung cancer mortality, and 53 percent if they lived in truly rural areas. Thus, for females, the difference of 12 percentage points might be attributed to the urban environment. The magnitude of these differ- ences depends on the prevalence of lung cancer in the various sub- groups of the particular population studied. Hisroparuoiocy or Lune Tumors Classification of lung cancer by histologic type was discussed in the Surgeon General’s 1964 Report with the conclusion that the squamous, undifferentiated, and oat-cell carcinomas were far more frequently found in smokers than in nonsmokers, while adenocarcinoma was rela- tively more frequent in nonsmokers, especially women. Changes in the bronchial mucosa resulting from the inhalation of cigarette smoke in- cluded loss of cilia, basal cell hyperplasia, and the appearance of atypical cells with irregular hyperchromatic nuclei. These changes, it was concluded, were related to the premalignant process of the de- 140 velopment of invasive carcinoma. Auerbach (6) has more recently reported on a study of the pathology of the tracheobronchial trees of 339 men who died from causes other than lung cancer and of 63 men who died from lung cancer. Up to 55 cross-sections of the tracheo- bronchial tissue were studied in each case. The 389 non-lung cancer cases included 65 men who had never smoked cigarettes and 274 men who had smoked in various amount. Figure 3 shows that only 1.38 percent of the slides from those who never smoked regularly have 60 percent or more atypical cells, whereas 76 percent of the slides of those smoking more than two packs a day had 60 percent or more atypical cells. (See figs. 3 and 4). PERCENT OF SLIDES WITH LESIONS SHOWING 60% OR MORE ATYPICAL CELLS 92.1 76.8 34.9 3.4 4.7 3 cCm71 1 Never Smoked 6 24 211 Adenocarcinoma. ..---------------------- 2 1 56 source: Ashley, D. J. B., et al. [(/) Table 4.] Insufficient information is provided in this study to specify in detail the past smoking histories, but the data suggest that cigarette smoking may be related to adenocarcinoma in some instances. . The preceding studies indicate that squamous, undifferentiated, and oat-cell carcinoma rarely occur in nonsmokers. However, it appears that cigarette smoking may also be associated with alveolar cell car- cinoma and glandular carcinoma of the bronchi. This relationship has been previously suspected. In fact as early as 1950 Wynder and Gra- ham (105) demonstrated this relationship. This was also shown in the study by Haenszel (39). Greater standardization and precision of diag- noses are needed to establish how few cases of undifferentiated or squa- mous carcinoma occur in nonsmokers who have been established to have never smoked appreciable amounts during their lifetimes. If 100 per- cent accurate smoking histories were obtainable on every case of lung cancer, it is suspected that very few cases of undifferentiated or squa- mous cancer would be found in persons who had never smoked. A report (98) on lung cancer in uranium miners noted a frequency of lung cancer, occurring almost entirely in the cigarette-smoking miners, greater than the frequency to be expected in a similar sized cigarette-smoking nonuranium mining population. A recent report (85) on bronchogenic carcinoma in asbestos workers also noted an in- creased frequency of lung cancer, occurring entirely in the cigarette smoking asbestos workers. This frequency was greater than the fre- quency to be expected for a similar population of cigarette smokers who were not asbestos workers. These reports suggest that cigarette smoking may interact with certain other environmental exposures to increase the frequency of lung cancer occurrence still further. Analysis of occupation and other environmental exposures must be performed simultaneously to detect which interactions with smoking seem to be especially dangerous. 148 EXPERIMENTAL PutmMonary CARCINOGENESIS Experimental attempts to produce lung cancer involve the admin- istration of tobacco smoke condensates and of carcinogens known to be present in tobacco smoke, either in vitro to preparations of cells or im vivo in experimental animals. Difficulties are encountered with the viability of tissue cultures and experimental animals when subjected to these various substances. Studies of human tissue from lung cancer patients indicate that abnormalities of the tracheobronchial mucosa, such as loss of cilia, basal cell hyperplasia, squamous metaplasia, and cellular atypism are important in the pathogenesis of human lung cancer caused by smoking. These changes have been experimentally produced in dogs exposed to cigarette smoke through a tracheostomy (2, 79, 80). A large number of dogs is now being studied to determine if lung cancer can be experimentally produced by this technique; if the dogs continue to smoke for a longer time, malignant changes may ap- pear subsequent to the already noted premalignant changes. The squa- mous metaplasia involved in the premalignant changes may explain why cigarette smoke condensate most readily produces cancer in the squamous epithelium of the skin of laboratory animals. AppitionaL Evipence ConcerNING EXPERIMENTAL CARCINOGENESIS The inhalation of tobacco smoke by mice was reported to increase the frequency of glandular tumors (37, 41, 63, 70). Syrian hamsters exposed to cigarette smoke developed a small number of tumors in the tracheobronchial epithelium (30, 1/0). Cigarette smoke condensate has been studied in tissue culture preparations (38), and implantation of cigarette smoke condensate exposed lung tissue subcutaneously has been reported to cause malignant growths (26). Cigarette smoke con- densate also causes skin tumors when applied topically (9, 11, 46, 48, 61, 74, 82, 107, 108). This was confirmed by a large-scale study with about 8,000 mice by the Tobacco Industry Research Council of England (22). Repeated injections of cigarette smoke condensate in rats produced sarcomas (32, 82, 83, 84). Since 1963 two studies have reported nega- — tive results when cigarette smoke condensate was administered intra- tracheally to rats and Syrian hamsters (25, 42) , respectively. Bronchoscopic painting of cigarette smoke condensate rapidly causes squamous metaplasia in dogs and may accelerate carcinogenesis (91). Carcinogens, known to be present in tobacco smoke, have been applied to cells in tissue culture with the observation of malignant changes (7) and other effects (22), such as differential growth inhibition of normal but not malignant cells (2%). Inhalation (53, 78, 90), intratracheal administration (25, 36, 42, 54, 81), subcutaneous, intraperitoneal and intravenous injection, oral administration, and skin painting of car- cinogens have all induced pulmonary tumors (87). 144 The search continues for an experimental animal system in which the inhalation of tobacco smoke will produce malignant tissue changes closely approximating those observed in human pulmonary cancer. When dealing with passive inhalation of tobacco smoke, however, a problem of the defensive barrier of the nasal passage is introduced. So far, dogs inhaling cigarette smoke through tra- cheostomies seem to be the most promising system, but there are problems in keeping the experiments going for the length of time nec- essary for lung cancer to develop. Additional research is needed. using cultured lung tissue together with autograft and homograft studies to determine in vivo results. Additional insight may thus be gained into in vivo systems. It should be noted, however, that it may not be possible ever to achieve histologic identity in pulmonary cancer production, not only because of difficulties in duplication of man’s smoking action for reasons of anatomic and physiologic differences, but also because of inherent species’ differences in cellular response. CANCER OF THE BUCCAL CAVITY AND PHARYNX (LIP, MOUTH, THROAT) The Surgeon General’s 1964 Report concluded that the causal re- lationship of pipe smoking to the development of cancer of the lip appeared to be established. Although there were suggestions of a relationship between cancer of other specific sites of the oral cavity and the several forms of tobacco use, their causal implications could not be stated at that time. The National Center for Health Statistics (94) reports that during 1964, 28 female and 157 male deaths occurred from cancer of the lip. During the period 1950-64, male mortality from this disease declined about 67 percent. This was partially due to changes in the diagnostic classification but was mainly due to increased early diagnosis and therapy. During the period 1958-64 when the seventh revision of the International Classification of Diseases was in use, total mortality from cancer of the lip remained about the same, but when analyzed by age, substantial decreases occurred in this death rate for each 10- year age group from 55-84 years. As for cancer of the oral cavity, other than the lip, the total death rate showed no marked variation from 1950-64 (3.1 and 3.3 deaths per 100,000 population, respectively). In 1964, the death rate for cancer of these sites in the male population was about three times the cor- responding rate in the female population (5.1 and 1.6 deaths per 100,000 population, respectively). 145 Morratrry Data From tae Larce Prosrecrive Sruprs Hammond (40) has reported data for males having cancer of the buccal cavity or pharynx, as the underlying cause of death, by mor- tality ratio and age-standardized death rates (table 12). TABLE 12.—Buccal cavity and pharyngeal cancer mortality ratios and death rates for male smokers, by type and specified age groups Cigarettes Pipe and/or Males Males Males 45-04 years 65-79 years 55-84 years Mortality ratio. _-__...--.--_____. . 9. 90 2. 93 4,94 Death rates____.-....22-- 222 +e 1(1) 8 '(7) 20 1(3) 15 ' Numbers in parentheses indicate death rates of persons who had never smoked cigarettes regularly. Source: Hammond, E. C. (40). The Dorn study (49) also has provided information with relation to amount and type of smoking on males dying from cancer of the buccal cavity and pharynx (table 13) : TaBLEe 13.—Buccal cavity and pharyngeal cancer mortality ratios and death rates for U.S. veterans, by age, type, and amount of smoking Current smokers of cigarettes only Pi Cigars Pipe Number of cigarettes per day and/or| only | only cigars 0 1-9 10-20 | 21-39 | 40+ Buccal Cavity: Mortality ratio....-......--.-.-. 10 0.86 2.93 7. 34 5.73 3. 89 4.11 3.12 Death rates: Age 45 to 54__ - 2B 97 Age 55 to 64__. 222 2 3 6 12 9 5 3 2 Age 65 to 74. _. 222-22 2-8. 4 fee 10 19 9 15 18 u Age 75 plus. -- 12