Changing epidemiology of lung cancer. Increasing incidence in women.

Recent worldwide reports show a large increase in the incidence of lung cancer in both men and women. To detail changes in the epidemiology of lung cancer relating to the incidence in men and women, we reviewed the patterns of diagnosis of 1145 patients with lung cancer seen at the Lahey Clinic between 1956 and 1972, during which time the proportion of all men and women seen was unchanged. The total number of women with lung cancer increased greatly and has almost doubled during this period. Lung cancer in women is now increasing at a faster rate than in men so that the male to female incidence has decreased from 6.8/1 (1957 to 1960) to 2.4/1 (1969 to 1972). We reviewed in detail the case histories and pathology of 231 women with lung cancer. No significant change was evident in cell type distribution during the study years. The most frequently seen tumors in women were adenocarcinoma (31 per cent), undifferentiated large cell cancer (22 per cent), epidermoid carcinoma (16 per cent), and undifferentiated small cell carcinoma (12 per cent). Among those women with known smoking histories, the group most responsible for the recent increase in women with lung cancer was comprised of smoking women in whom Kreyberg group 1 (smoking-related) tumors developed.