DETERMINANTS OF REGIONAL DIFFERENCES IN LUNG-CANCER MORTALITY IN THE NETHERLANDS

Although regional differences in lung cancer mortality are likely to b e attributable to regional differences in tobacco smoking, studies in various countries found only weak relationships. This paper aimed at e xplaining regional differences in lung cancer mortality in the Netherl ands. In a first step, clues for the role of smoking were obtained fro m a detailed description of regional mortality differences. These diff erences were found to be strongly determined by cohort effects: they v ary between birth cohorts, and have been stable for over 30 years. Reg ional mortality differences reflect a diffusion of the lung cancer epi demic from high-income regions to low-income regions. These findings a re suggestive of a relationship with regional differences in trends in cigarette smoking. In a second step, by means of multiple regression analysis, mortality differences in 1980-84 were related to available d ata on cigarette smoking and two other possible risk factors: work in transport and manufacturing industry, and air contamination. The indep endent variables referred to the 1970s. Positive associations with var ious smoking measures were found for women, but for men the associatio ns were weak or non-existent. Mortality differences among men 45-64 ye ars were associated with work in transport and manufacturing industry. Strong associations with air contamination were found for men and wom en 65 years and older. Additional analysis showed that regional differ ences in lung cancer among old men were strongly associated with smoki ng in 1930, i.e. half a century before. Changes in the regional patter n of tobacco consumption between 1930 and 1970 explain why smoking in 1970 is not associated with mortality differences in the 1980s. This s hows that the explanation of regional lung cancer death rates sometime s has to go far back in time. The strong association with air contamin ation does not constitute firm evidence of an effect, but should be co nsidered as a stimulus to carry out further analysis on the excess lun g cancer mortality in polluted regions.