Is smoking sufficient to explain the large difference in lung cancer incidence between Finland and Norway?

In the 1960s, lung cancer among Finnish men was about 3.5 times as common as among Norwegian men. A study by Pedersen et al. in 1962 indicated that the difference in contemporary smoking habits could account for only part of the difference in lung cancer incidence in men between the countries. In that study, smoking habits in Finland and Norway were investigated via interviews of 8,700 people from six areas of each country. For the present study the Finnish and Norwegian cancer registries have followed lung cancer morbidity in those areas. When the interval between the recording of smoking habits and lung cancer incidence was 15 years, after adjustment for age and smoking habits, the Finnish males had a relative risk between 1.1 and 1.6 compared with Norwegian men. The results suggest that, given a sufficiently long latency period, almost the entire difference between Finnish and Norwegian men could be attributed to smoking habits.