Lung cancer and smoking in Danish women

In most developed countries, including Denmark, cancer of the lung is the most frequent malignant disease among men, whereas the problem is less among women. Examination of Danish mortality data for the period 1931 to 1972 reveals a 5-fold increase in female rates as opposed to a 16-fold increase in male rates. Since about 1960 female rates have, however, increased faster than male rates with a consequent decline in the male-female ratio. It is demonstrated that more recent female birth-cohorts have higher mortality rates than the older ones. The increasing mortality from lung cancer among more recent female cohorts is shown to parallel increasing proportions of smokers in these cohorts. Further data are presented to indicate that not only is smoking more widespread among young than among old women, but the proportion of cigarette smokers among all smokers falls from 98% in the youngest to 33% in the oldest age-group. No causal relationship between smoking and lung cancer can be claimed from the evidence presented. The present findings are, however, what would be expected if cigarette-smoking were an aetiological factor in female lung cancer.