Objectives: In order to further characterize the effect of gender on the clinicopathologic features and survival of patients with lung cancer, and to determine gender-associated differences in temporal trends, we analyzed data that had been entered into a population-based cancer database.
Patients and methods: Data on demographics, stage at diagnosis, histology, initial therapy, and survival were obtained on all patients with primary bronchogenic carcinoma registered in the national Surveillance, Epidemiology, and End Results database from 1975 to 1999.
Results: Of the 228,572 eligible patients, 35.8% were female. The median age at diagnosis was 66 years for both men and women. However, women accounted for 40.9% of patients who were < 50 years of age and for 35.4% of older patients. The incidence of lung cancer in men peaked at 72.5 per 100,000 person-years in 1984 and then declined to 47 per 100,000 person-years by 1999. In women, the incidence continued to rise to a peak of 33.1 per 100,000 person-years in 1991 before reaching a plateau at 30.2 to 32.3 per 100,000 person-years from 1992 to 1999. These changes have resulted in a marked narrowing of the male/female incidence ratio from 3.56 in 1975 to 1.56 in 1999. As initial treatment, women with local disease underwent surgery more frequently than did men. Stage-specific survival rates were better for women at all stages of disease (p < 0.0001). In a multivariate analysis, male gender was an independent negative prognostic factor (p < 0.0001).
Conclusion: The incidence rate of lung cancer in women in the United States has reached a plateau. However, women are relatively overrepresented among younger patients, raising the question of gender-specific differences in the susceptibility to lung carcinogens. At each stage of the disease, the relative survival of women is better than that of men, with the largest difference noted in patients with local disease.