The general objective of the project is to provide, on the basis of European data, an estimate of the disease burden from exposure to environmental tobacco smoke (ETS) in Europe, in particular the long-term effects. This should serve as a sound non-objectionable basis to sustain the development of public health on this key aspect of the tobacco smoking issue.
The major specific objective is a quantitative estimation, obtained with improved methodology, of exposure assessment and study design in respect to already existing studies of lung cancer in nonsmokers. Ancillary objectives are the evaluation of the relationship between ETS and cancers other than lung in adults and children, as well as chronic obstructive lung disease and lung function impairments in adult nonsmokers.
Research is being carried out in order to provide, on the basis of European data, an estimate of the disease burden from exposure to environmental tobacco smoke (ETS) in Europe. The quantitative estimation of exposure assessment will be obtained through improved methodology and study design in respect to already existing studies of lung cancer in nonsmokers.
The data collection started in 1989. Data on cases and controls are being edited, and incorporated into an international database for analysis. By the end of 1992 the recruitment was increased on average by 50%. Through conservative estimates of the likely intake of cases of lung cancer in nonsmokers has been made in the planning phase, it has become clear that the proportion of nonsmokers is (even in females) in most centres lower than expected. The provisional diagnosis of lung cancer for smokers who are recruited and interviewed as such for the study, is later histologically confirmed in a large proportion of the cases. For nonsmokers the proportion of confirmed cases is much lower, of say 50% or less. In other words, the exposure status (being a smoker) is a powerful predictor of a correct diagnosis. Because of the comparatively low proportion of confirmations among nonsmokers, the rate of accrual of lung cancers in nonsmokers is lower than predicted or expected. This provides an instructive example of how even a group of investigators, almost all with substantial previous experience of case control studies on a variety of cancers, may still, after having explicitly considered the issue on the basis of their preceding experience, materially underestimate the rate of accrual of cases in a study.
About 30 samples had been collected by December 1992 for the genetic susceptibility study. Of these 6 have been transferred to the International Agency for Research on Cancer (IARC). Critical reviews have been produced on the relationship between ETS and the risk of cancer in adults, ETS exposure during pregnancy and childhood and cancer risk, and ETS and adult nonneoplastic respiratory diseases.