Gender-specific incidence trends in lung cancer by histological type in Sweden, 1958-1996.

We used the Swedish Family-Cancer Database to examine the time trends of lung cancer in Sweden by histological type, with special reference to gender. A total of 45,297 lung cancer cases were analysed. The overall age-adjusted incidence rates of squamous cell carcinoma (SCC) in men peaked in the 1980s and then slightly decreased, while corresponding rates in women increased steadily. The incidence of adenocarcinoma increased in both genders. The male-to-female incidence ratio for SCC was 12.4 in the 1960s and 3.6 in the 1990s. For adenocarcinoma the ratio was close to 1.5 throughout the period. Regression analysis indicated that the birth cohort of the 1940s was at the highest risk for adenocarcinoma in men and for all types of lung cancer in women. Lung cancer in parents was a risk factor for offspring. In conclusion, the data, particularly on women, suggest that modern cigarettes induce lung adenocarcinoma and SCC in a proportion of 1:0.6. This proportion was 1:3.7 among men diagnosed in the 1960s. The incidence ratio of 1.3 for adenocarcinoma between men and women in the 1990s is consistent with the smoking prevalence data a few decades ago, suggesting equal sensitivity of both genders to tobacco-induced lung cancer.