LETTERS

The first reports on smoking and lung cancer – why are they consistently ignored?

George Davey Smith^I,1; Matthias Egger^II

^IDepartment of Social Medicine, University of Bristol, Canynge Hall, Whiteladies Road, Bristol BS8 2PR, England (email: zetkin@bristol.ac.uk)
^IIInstitute for Social and Preventive Medicine, University of Berne, Switzerland

Editor – In his commentary on early reports on smoking and lung cancer, Michael J. Thun ignores the actual first reports and concentrates on the series of case-control studies published in 1950, first in the United States and then in the United Kingdom (1). He also claims (as others have done) that in the pre-1950 era the most popular hypothesis was that "lung cancer mortality ... was more likely to have resulted from the widespread tarring of roads and exhaust from motor vehicles than from cigarette smoking". Could he please produce contemporary – i.e. pre-1950 – references on this hypothesis that match the veritable mountain of publications from pre-1950 implicating cigarette smoking (2), in particular, formal analytical studies of road tarring and motor exhaust similar to the many analytical studies of smoking and lung cancer?

Of course, as is now well known (3, 4, 5–10), extensive research on smoking and lung cancer appeared before 1950, much – but not all – of it from Weimar and then Nazi Germany. In 1928 Schönherr from Chemnitz drew attention to the high rates of smoking in a series of lung cancer patients (11). He explicitly studied where the lung cancer cases lived and reported they were not closer to roads than expected (tar and exhaust already being an unsupported hypothesis) and suggested that lung cancer in non-smoking wives of smokers was caused by passive smoke inhalation. In his comprehensive review of smoking and lung cancer in 1929 (reviews were already being written 20 years before the 1950 "discovery") the influential actuary Frederich Hoffman wrote: "Unfortunately, German statistical discussions are invariably confusing and complicated by the omission of proper headings to statistical tables, which makes a full use of the elaborate investigation by Schönherr exceptionally difficult. Exceedingly rigorous reading is required to draw the best results from the mass of evidence presented. But every aspect of the problem is considered by this author, whose observations are deserving of being completely translated into English" (12). In a review published two years later, Hoffman considered that "smoking habits unquestionably increase the liability to cancer of the mouth, the throat, the oesophagus, the larynx and the lungs" (13).

In 1935, Fritz Lickint published an elegant synthetic review that considered time trends in lung cancer and cigarette smoking, ecological associations between smoking and lung cancer, autopsy series, experimental animal studies and clinical reports, which left him in no doubt that smoking was a cause of lung cancer (14). He had entitled a 1929 paper "Tobacco and tobacco smoke as etiological factors for carcinoma" (15); he simply did not think further studies were needed – what was required was to prevent smoking. His extraordinary 800-page work in 1939 (16) summarized all that was currently known from scientific research on the health consequences of smoking.

In 1939, a study of smoking habits of lung cancer cases compared with those of an ill-defined control group carried out by Franz Müller appeared in the Zeitschrift für Krebsforschung (17), a leading international cancer journal of its time (a time when many of the major science journals were in German). Four years later a considerably more sophisticated study by Schairer & Schöniger appeared in the same journal (18); an English translation is now readily accessible (19). This study involved a population and hospital control group (findings were similar in both), analysed the potential effect of people with illnesses quitting smoking, and tabulated results of their study together with previous data to show consistency (a formal statistical meta-analysis was not, unsurprisingly, performed. The odds ratios that can now be calculated from these early studies are very similar to those of the later studies published in the 1950s, and for the Schairer & Schöniger study alone statistical evidence for an association can be shown to be strong (P < 0.0000001).

The study by Schairer & Schöniger was carried out under the auspices of the Institute for the Struggle Against the Dangers of Tobacco based in Jena and supported, in part, by Adolf Hitler's personal funds. The history of anti-smoking activity in Nazi Germany and its links to the practice and ideology of the ruling party have been discussed in detail elsewhere (3, 5, 6), but there was no simple connection between science and ideology. For example, Fritz Lickint – the most scholarly, best informed and active scientist in this field during the Nazi period – had been a supporter of the Social Democrats and, as one of us (GDS) discovered on a visit to the archives of the Institute in 1994, was subject to an SS investigation because of his suspect (anti-Nazi) politics and was denied employment at the Institute because of this.

The understandable concern that acknowledging the roots of scientific investigation of the links between smoking and lung cancer may discredit anti-tobacco activity today is neither congruent with the multifaceted (and in no way simply "Nazi") history of such science or with a true account of the complex development of scientific ideas.

Competing interests: none declared.

References

1. Thun MJ. When truth is unwelcome: the first reports on smoking and lung cancer. Bull World Health Organ 2005;83:144-5.

2. Larson PS, Haag HB, Silvette H. Tobacco: experimental and clinical studies. Baltimore (MD): The Williams and Wilkins Company; 1961.

3. Davey Smith G, Ströbele SA, Egger M. Smoking and health promotion in Nazi Germany. J Epidemiol Community Health 1994;48:220-3.

4. Davey Smith G, Ströbele S, Egger M. Smoking and death (letter). BMJ 1995;310:396.

5. Proctor R. The Nazi war on cancer. Princeton (NJ): Princeton University Press; 1999.

6. Davey Smith G. Lifestyle, health, and health promotion in Nazi Germany. BMJ 2004; 329:1424-5.

7. Doll R. Commentary: Lung cancer and tobacco consumption. Int J Epidemiol 2001;30:30-1.

8. Procter RN. Commentary: Schairer & Schöniger's forgotten tobacco epidemiology and the Nazi quest for racial purity. Int J Epidemiol 2001;30:31-4.

9. Zimmermann S, Egger M, Hossfeld U. Commentary: Pioneering research into smoking and health in Nazi Germany – the Wissenschaftliches Institut zur Erforschung der Tabakgefahren in Jena. Int J Epidemiol 2001;30:35-7.

10. Ernst E. Commentary: The Third Reich – German physicians between resistance and participation. Int J Epidemiol 2001;30:37-42.

11. Schönherr E. Beitrag zur Statistik und Klinik der Lungentumoren [Contribution to the statistical and clinical features of lung tumours] Krebsforsch Z. 1928;27:436-50.

12. Hoffman FL. Cancer of the lungs. American Rev Tuberc 1929;19:392-406.

13. Hoffman FL. Cancer and smoking habits. Ann Surg 1931;93:50-67.

14. Lickint F. Der Bronchialkrebs der Raucher [Bronchial cancer of smokers]. MMW 1935;82:122-4.

15. Lickint F. Tabak and Tabakrauch als aetiologischer Faktor des Carcinoms [Tobacco and tobacco smoke as etiological factors for cancer]. Krebsforsch Z. 1929;30:349-65.

16. Lickint F. Tabak und Organismus [Tobacco and the organism]. Stuttgart: Hippokrates Verlag, 1939

17. Müller FH. Tabakmissbrauch und Lungencarcinom [Tobacco abuse and lung cancer]. Krebsforsch Z. 1939;49:57-85.

18. Schairer E, Schöniger E. Lungenkrebs und Tabakverbrauch [Lung cancer and tobacco consumption]. Krebsforsch Z. 1943;34:261-269

19. Schairer E, Schöniger E. Lung cancer and tobacco consumption. Int J Epidemiol 2001;30:24-7.

1 Correspondence should be sent to this author.