LETTER TO THE EDITOR Dear Sir, Risk of lung cancer from exposure to environmental tobacco smoke from cigars, cigarillos and pipes Cigar smoking is becoming increasingly popular in the United States, and a similar trend might take place in Europe. Smoking of cigars, cigarillos and pipes has been considered to entail a smaller risk of lung cancer than smoking of cigarettes (IARC, 1986). We have published the results of a large Euro- pean study suggesting that the lower risk of lung cancer among cigar and pipe smokers compared to cigarette smokers is due mainly to their lower average cumulative amount of tobacco smoked (Boffetta et al., 1999). Three studies from the United States have reported results suggesting a risk of lung cancer following exposure to environmental tobacco smoke (ETS) from cigars, cigarillos or pipes similar to that found following exposure to ETS from cigarettes (Cardenas et al., 1997; Fon- tham et al., 1994; Garfinkel et al., 1985). To our knowledge, no such results have been reported for Europe. We have conducted a large case-control study of ETS and lung cancer among non-smokers in 12 European centres (Bof- fetta et al., 1998). Within that study, we collected information on the type of tobacco product smoked by the spouses of cases and controls. All smoking wives consumed cigarettes, precluding an analysis of male non-smokers. Some non-smoking women en- rolled in 8 of the centres (3 from Germany, 2 from Italy and 1 each from Spain, France and Sweden) were married to a smoker of cigars, cigarillos or pipes. We calculated the cumula- tive exposure to ETS as the number of grams of tobacco smoked daily by the husband in the presence of his spouse multiplied by the number of years of exposure. In calculating ETS exposure from non-cigarette products, we used equivalence weights of 2 g for one cigarillo and 4 g for one cigar; direct information on amount of pipe tobacco smoked was available. We calculated odds ratios (ORs) of lung cancer and 95% confidence intervals (CIs) after adjustment for age and study centre. We divided the exposed subjects into 2 categories separated by the 75th percen- tile of the distribution among controls since it has been sug- gested that misclassification of ETS exposure is less at high exposure levels (Becher et al., 1992). The OR of lung cancer in women for exposure to ETS from any type of tobacco product was 1.11 (95% CI 0.88–1.39) (Boffetta et al., 1998). The OR for exposure to ETS from cigarettes only was 1.05 (95% CI 0.82–1.35). After excluding the 4 centres without exposure to ETS from products other than cigarettes, the OR for exposure to ETS from cigars and pipes, alone or in combination with cigarettes, was 1.02 (95% CI 0.68–1.55, Table I). In Table I, we also report the results of the analysis by cumulative exposure to ETS from cigars and pipes: exposure to less than 260 g/years of tobacco from cigar, cigarillo or pipe (equivalent to 13 pack/years of cigarettes) was not associated with an increased risk of lung cancer. Exposure above that level entailed a non-significant increase in lung cancer risk. Thirteen exposed cases and 10 exposed controls reported exposure without specifying level of exposure to cigar, cigarillo or pipe ETS. Concomitant exposure to ETS from cigarette smoking by the husband was reported by most exposed subjects (40 cases and 58 controls). Adjustment for this factor did not affect the excess risk among subjects exposed to ETS from cigars and pipes (e.g., the ratio of ORs between the high and the low categories of exposure shown in Table I increased from 2.6 to 2.8). Our results are consistent with the hypothesis that, similar to exposure to ETS from cigarettes, high exposure to ETS from cigars and pipes may be associated with lung cancer risk. Yours sincerely, Paolo BOFFETTA 1 *, Fredrik NYBERG 1,2 , Antonio AGUDO 3 , Ellen BENHAMOU 4 , Karl-Heinz JO ¨ CKEL 5 , Michaela KREUZER 6 , Franco MERLETTI 7 , Go ¨ran PERSHAGEN 2 , Hermann POHLABELN 8 , Lorenzo SIMONATO 9 , H.-Erich WICHMANN 5 and Rodolfo SARACCI 1,10 1 International Agency for Research on Cancer, Lyon, France 2 Institute of Environmental Medicine, Karolinska Institute, Stock- holm, Sweden 3 Institute for Epidemiological and Clinical Research, Barce- lona, Spain 4 Gustave Roussy Institute, Paris, France 5 Institute for Medical Informatics, Biometry and Epidemiology, Essen, Germany 6 GSF Institute for Epidemiology, Munich, Germany 7 Unit of Cancer Epidemiology, University of Turin, Turin, Italy 8 Bremen Institute for Prevention Research, Bremen, Germany 9 Venetian Cancer Registry, Padua, Italy 10 National Research Council, Pisa, Italy Grant sponsor: European Commission; Grant number: EV5V-CT94– 0555; Grant sponsor: Association pour la Recherche sur le Cancer; Grant number: 90CVV01018; Grant sponsor: Caisse Nationale d’Assurance Maladie des Travailleurs Sociaux; Grant sponsor: Federal Ministry for Education, Science, Research and Technology; Grant number: 01 HK 546; Grant sponsor: Federal Ministry of Work and Social Affairs; Grant number: IIIb 7–27/13; Grant sponsor: Federal Office of Radiation Protection; Grant numbers: St Sch 1066; St Sch 4047; St Sch 4074/1; St Sch 4006; St Sch 4112; Grant sponsors: MURST; Italian Association for Cancer Research; Regione Piemonte-Ricerca Finalizzata; Grant sponsor: National Research Council (Italy); Grant number: 91.00327.CT04; Grant sponsor: Spanish Ministry of Health; Grant number: 89002300; Grant sponsor: Swedish Match; Grant number: 8913/9004/9109/9217; Grant sponsor: Swedish Environmental Protection Agency; Grant number: 5330071–1. *Correspondence to: International Agency for Research on Cancer, 150 cours Albert-Thomas, F-69008 Lyon, France. Fax: +33–4-72738342. E-mail: boffetta@iarc.fr Received 30 April 1999; Revised 19 June 1999 Int. J. Cancer: 83, 805–806 (1999)  1999 Wiley-Liss, Inc. Publication of the International Union Against Cancer Publication de l’Union Internationale Contre le Cancer