Dean F. Davies, M.D., Ph.D.

The American Cancer Society enteredactivelyintothewar againstlungcancerafter nationwide publicity had been givento clinical reports of an association between lung cancer and smoking. Duringthe ensuing seven years the Society hasbeenintheforefrontofthebattlelargelythrough support of research:

To date the American Cancer Societyhas awarded over 3.4 million dollars ingrants for research on lung cancer since1954.

The large-scale follow-up study carriedout by its own staff would have cost anestimated $10,000,000 without the help ofvolunteers.

Lung cancer conferences sponsored bythe Society were held in: Chocorua, NewHampshire in September, 1952; ProutsNeck, Maine in September, 1953; AtlanticCity, New Jersey in February, 1954; Glenburnie, New York in September, 1954; andPrinceton, New Jersey in January, 1955.

In March, 1955 an Ad Hoc ResearchAdvisory Committee on Lung Cancer wasformed which served the Society, (subsequently as the Advisory Committee on Research on Lung Cancer) until August,1959.

Under its sponsorship, the First Workshop Conference on Lung Cancer Researchwas held at Virginia Beach in November,1957; the Second Workshop Conference onLung Cancer Research was held at Harriman, New York, February-March, 1959.

Also under the sponsorship of the Advisory Committee on Research on LungCancer a “¿�CooperativePilot Study on theEvaluation of Radiologic and CytologicScreening of a Population for Early Diagnosis of Lung Cancer―was designed and isnow in its second year of operation in sixVeterans Administration Centers throughcooperation of the V. A. Central Office.

In June, 1956 a Study Group on Smoking and Health was formed under the jointsponsorship of the American Cancer Society, American Heart Association, National Cancer Institute and National HeartInstitute. Its report was quoted widely inthepressinMarch,1957andpublishedinScience 125:1129-1133,June 7, 1957.

Subsequently the Board of Directorsformed an Ad Hoc Committee on Smoking and Health which was superseded inJune, 1959 by the present Committee onTobacco and Cancer.

521 W. 57th Street, New York, N. Y.

The following authorities, agencies orspecially appointed advisory groups havestudied the problem independently andhave made statements indicating their conclusion that cigarette smoking is usuallyrelated to lung cancer:

1. Public Health Cancer Association2. Study Group on Smoking and Health3. British Medical Research Council4. Surgeon General of the U.S.P.H.S.,

Leroy Burney5. Swedish Medical Research Council6. Subcommittee on Tobacco and Air

Pollution, International UnionAgainst Cancer

7. Herman E. Hilleboe, Commissioner,New York State Health Department

8. Malcolm Merrill, Director, CaliforniaState Department of Public Health

The evidence which has accumulated oncigarette smoking and lung cancer largelyover the last decade is summarized belowin five categories:

Epidemiologic Evidence

After nine studies were published showing an increased incidence of sniokinghistory among lung cancer patients, theAnierican Cancer Society in 1952 begana study of smokers and nonsmokers todiscover any differences in subsequentdeath rates froni various causes. At approximately the same time two other follow-up studies were begun, one on physicians in England and the other on a groupof veterans of military service in theUnited States. Results of these threestudies have since been published andshow remarkable agreement: the incidence of lung cancer is between nine andten times as high among cigarette smokersas among nonsmokers. While these resultswere being obtained, about fifteen additional studies on lung cancer patientsshowed a history of smoking to be associated with the disease. No one has suggested a basis whereby all of these positivecorrelations could be in error. Nevertheless, such “¿�statistical―evidence alone is insufficient to establish a causal relationship.

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A Statement on Lung Cancer

ards) could account for 10 or 15 per centof the total. Cigarette smoking, then, isassociated with well over half the cases oflung cancer in the country. Of the remainder, there is no evidence that environmental causes are significantly involved in15 percent.

It has been estimated that one of tensmokers will eventually die of lung cancer.The probability of getting the disease isgreater the more one smokes. The habithas been compared with the game of Russian roulette. The analogy niay be dcccivin@ to the player. Lung cancer accountsfor only about 15 per cent of the total increased mortality rate of smokers. If alung cancer bullet takes up one cylinderit seems likely froni the evidence that someof the others are loaded with other diseases.

The possibility exists that factors of resistance operate in some whose naturallife expectancy is not shortened by smoking. It is also not unlikely that factors ofsusceptibility and other external influencesoperate with cigarette smoking in producing lung cancer. Smokers do tend to differfrom nonsmokers in several respects whencompared in sufficiently large numbers,but these differences cannot account forto nine-to ten-fold excess of lung cancerdeaths among smokers.

Despite the accumulated evidence, it isof course true that there is no mathematcal proof that cigarette smoking causes

lung cancer. However, decisions in thepublic interest must be made by agenciesand individuals responsible for publichealth on the basis of the available evidence. The American Cancer Society considers the facts adequate and concludesthat CIGARETTE SMOKING IS THE MAJOR

CAUSATIVE FACTOR IN LUNG CANCER.

This disease offers a greater opportunityfor cancer prevention than any other typeof cancer. The discoveries of the lastdecade in lung cancer research representa breakthrough in the truest sense. Thefringe benefits to be derived from applications of this new knowledge in terms ofprevention of death from other diseasesniay well exceed the potential gains inlung cancer prevention.

Chemical Evidence

Fifteen carcinogenic agents, of whichfourteenare polycyclichydrocarbons,have been reported to be present in cigarette smoke condensate. The other agentis arsenic which is known to be carcinogenic for human skin. Two of the othercompounds have produced epidermoidlung cancers in the mouse, rat and hamster.

In addition to the carcinogens, cigarettesnioke condensate is made up of a host ofcompounds of which the major one is nicotine. Of the pharmacologic effects of nicotine, one leads to slowing of ciliary actionin the tracheobronchial tree and anotheris vascular and bronchial constrictionthrough release of adrenaline. Both theseeffects tend to decrease the efficiency ofremoval of foreign substances from therespiratory tract.

Biologic Evidence

Tobacco smoke condensates have produced cancers on the skin of mice andrabbits. Lesions resembling cancer or carcinoma in situ have been reported in tissue cultures, on the mouse cervix, and ondog and mouse bronchial epithelium afterexposure to tobacco smoke or its condensate.

Pathologic Evidence

The tracheobronchial trees of smokersand nonsniokershavebeenhistologicallyexamined extensively at autopsy. Theseverity of pathologic epithelial changesincluding metaplasia and carcinoma in situincreased as the history of smoking increased. Invasive lung cancer was foundonly among smokers.

Quantitative Relationships

Examinationsof numerousreportsoflung cancer indicate that about 15 percentareadenocarcinomatousand bronchiolar types not believed to be of environmental origin. Smoking does not accountfor all the remainder. Best estimates indicate that urban factors (probably atniospheric pollution and occupational haz

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