Lung cancer is the leading cause of cancer-related death worldwide. The aim of the KBP-2020 study was to describe survival among patients diagnosed with lung adenocarcinoma in France in 2000, 2010, and 2020, outside academic medical centers. We collected prospective data from all patients diagnosed with lung cancer in nonacademic public hospitals in France in 2020. We compared these data with those from similar studies performed in 2000 and 2010 to map the evolution of survival. The KBP-2020 cohort comprised 5015 patients with lung adenocarcinoma. The 3-year overall survival (OS) rate was 38.6%, ranging from 21.3% among patients with metastatic disease at diagnosis to 84.0% for those with stage I disease at diagnosis. The median OS in the overall population more than doubled in 20 years, from 8.5 months in 2000 to 20.7 months in 2020. Female sex, higher performance status, and earlier disease stage were associated with an increased 3-year OS. Patients with metastatic lung adenocarcinoma with EGFR, ALK, or ROS1 molecular alterations who were treated with targeted therapy had a higher 3-year OS rate than such patients without these alterations - 36.0% versus 18.5%. Among those patients with metastatic disease without the above-noted molecular alterations, the 3-year OS rate was 36.2% with first-line immunotherapy versus 14.3% without immunotherapy, and median OS was 21.0 months versus 4.2 months. Improvements in the OS of patients with lung adenocarcinoma were seen over 20 years in this setting of nonacademic public hospitals in France. Targeted therapy and immunotherapy were associated with longer OS among patients with metastatic disease. (Le Nouveau Souffle and others; trial registration number, NCT04402099.).