After a prolonged period of increasing rates of lung cancer incidence and mortality for both men and women, incidence and mortality rates are decreasing in men and stabilizing in women. The goal of this study was to assess changes over 20 years in the prevalence of known risk factors for lung cancer and to elucidate possible predictors associated with lung cancer survival. The study included a total of 908 patients with primary lung cancer referred to The University of Texas M.D. Anderson Cancer Center over three study periods 1985-1989 (N=392), 1993-1997 (N=216), and 2000-2004 (N=300). Detailed questionnaires were used to collect information from the patients. Hazard ratios were estimated by fitting a Cox proportional hazards model. Using the Kaplan-Meier method, survival in months was calculated up to 2 years from the date of diagnosis to achieve comparability in the three groups. We observed a decrease in the proportion of patients who are current cigarette smokers and an increase in the proportion of patients who present with adenocarcinoma of the lung, are obese and patients who present with localized disease. We also found an increase in the number of patients who report a family history of lung cancer. The overall median survival duration has increased over the years from 12.0 months in 1985-1989 to 17.5 months in 2000-2004. Also, the probability of survival of patients who were alive at 2 years after diagnosis has also increased (26.5% in 1985-1989 to 40.8% in 2000-2004). Overall, women had a better median survival than men. The results show that the demographic, histologic, clinical, and outcome variables of patients with lung cancer have changed over the past 20 years. Most important, the survival of patients with lung cancer has improved.