World-wide differences in the sex ratio of bronchial carcinoma

1. 1. The sex ratio of the incidence of bronchial carcinoma varies widely in different parts of the world, ranging from 13·5 : 1 in Holland to 1 : 1 in Nigeria. 2. 2. The incidence, the proportion of cell types and the site of the growth in European peoples are different from those among non-European peoples. 3. 3. On the basis of lung cancer sex ratio, the world can be divided into two groups: Europeans and people elsewhere in the world of predominantly European origin and non-Europeans. There are very few exceptions to this generalization. 4. 4. The sex ratio is not related to the total incidence of the disease when the European and non-European groups are separately considered. 5. 5. The variation in ratio is due to the different incidence amongst the men. 6. 6. There is no relationship between the sex ratio and the total tobacco consumption in different countries. 7. 7. The variation in the sex ratio is not due to the different age structure of the different populations. 8. 8. The differences in sex ratio tend to follow the pattern of that of the ethnic group in peoples living in the same country. 9. 9. It is suggested that there is a genetic factor in the aetiology of bronchial carcinoma.