Abstract
Background
Despite the fact that tobacco is a well-recognized risk factor for pancreatic cancer, no study has yet reported on the association between environmental tobacco smoke (ETS) and this malignancy. We investigated the relationship between pancreatic cancer and childhood and adult exposure to ETS using a case-control study design.
Methods
Our study population consisted of 583 pancreatic cancer cases and 4,813 population-based controls that were identified within 8 Canadian provinces between 1994 and 1997. Mail-out questionnaires were used to collect risk factor information and a lifetime residential and occupational history of exposure to ETS.
Results
Among never smokers, those who were exposed to ETS both as a child and as an adult had an odds ratio of 1.21 (95% CI=0.60-2.44) relative to those with no exposure. For active smoking, when the referent group consisted of never smokers who had not been regularly exposed to ETS, the risk increases were more pronounced with an increased number of years of smoking, cigarette pack-years, years since quit smoking, and average number of cigarettes smoked daily.
Conclusions
Overall, our results are suggestive of a weak association between pancreatic cancer and ETS. Perhaps more importantly, they suggest that ETS smoking exposures may confound the risk of pancreatic cancer associated with active smoking measures commonly used in epidemiologic studies.
Résumé
Contexte
Bien que le tabac constitue un facteur de risque bien connu pour le cancer du pancréas, aucune étude n’a encore constaté d’association entre la fumée secondaire du tabac (FST) et ce type de tumeur maligne. À l’aide d’une étude cas-témoin, nous avons analysé la relation entre le cancer du pancréas et l’exposition à la FST durant l’enfance et à l’âge adulte.
Méthode
La population à l’étude comprenait 583 cas de cancer du pancréas et 4 813 témoins représentatifs identifiés dans huit provinces canadiennes entre 1994 et 1997. Nous leur avons posté des questionnaires pour recueillir de l’information sur leurs facteurs de risque et leurs antécédents d’exposition à la FST, à la maison et au travail, au cours de leur vie.
Résultats
Chez les personnes n’ayant jamais fumé, celles qui avaient été exposées à la FST durant l’enfance et à l’âge adulte avaient un rapport de cotes de 1,21 (IC de 95% =0,60-2,44) comparativement aux personnes non exposées. Pour les fumeurs actifs (comparés à un groupe de référence composé de personnes n’ayant jamais fumé et n’ayant pas été régulièrement exposées à la FST), l’accroissement du risque était plus prononcé avec le nombre d’années de tabagisme, le nombre de paquets de cigarettes par année, le nombre d’années depuis le renoncement au tabac et le nombre moyen de cigarettes fumées quotidiennement.
Conclusions
Dans l’ensemble, nos résultats semblent indiquer une faible association entre le cancer du pancréas et la FST. Ils soulignent néanmoins un fait intéressant: l’exposition à la FST pourrait être un facteur de confusion dans les mesures couramment utilisées par les études épidémiologiques pour évaluer le risque de cancer du pancréas associé au tabagisme actif.
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