Women with lung cancer appear to have better survival compared to men. Whether this is due to differences in treatment, tumor biology, or due to a longer life expectancy is not clearly understood. This study sought to evaluate whether there are gender differences in lung cancer survival after controlling for competing causes of death and type of treatment.
This study included 18,967 cases of histologically confirmed, Stage I and II non-small-cell lung cancer diagnosed between 1991 and 1999 from the Surveillance, Epidemiology and End Results registry linked to Medicare records. Patients were grouped in three categories according to the treatment received: surgery, radiation or chemotherapy but no surgery, and untreated cases. We used stratified analyses and multivariate models to identify gender differences in survival among these groups using three methods to control for competing causes of death: lung cancer specific survival, overall survival adjusting for comorbidities, and relative survival calculated by the life-table method.
Women in the three treatment groups had better cancer specific, overall, and relative survival than men (p <0.0001 for all comparisons). Lung cancer specific 5-year survival for women was 54% compared to 40% for men (p<0.0001). Among untreated patients, women had approximately a 25% decreased risk of death compared to men. Stratified and multivariate analyses showed that women had significantly better survival than men after controlling for age, race, stage at diagnosis, histology, median income, geographic area, access to care, and type of treatment.
In this national, population-based sample, women with non-small cell lung cancer had better risk-adjusted survival rates compared to men in all treatment groups. That this gender difference was observed among untreated patients suggests that lung cancer in women has a different intrinsic biologic behavior and natural history that in men.
These gender difference in survival have implications in the design and interpretation of lung cancer trials and could be incorporated in the current prognostic classification.
Juan Wisnivesky, None.