Aim: To describe initial treatment patterns and survival of patients diagnosed with non-small-cell lung cancer (NSCLC) in Denmark, before immune checkpoint inhibitor and later-generation tyrosine kinase inhibitor use. Patients & methods: Adults diagnosed with incident NSCLC (2005-2015; follow-up: 2016). Initial treatments and overall survival (OS) are reported. Results: 31,939 NSCLC patients (51.6% stage IV) were included. Increasing use of curative radiotherapy/chemoradiation for stage I, II/IIIA and IIIB NSCLC coincided with improved 2-year OS. Systemic anticancer therapy use increased for patients with stage IV non-squamous NSCLC (53.0-60.6%) but not squamous NSCLC (44.9-47.3%). 1-year OS improved in patients with stage IV non-squamous NSCLC (23-31%) but not squamous NSCLC (22-25%). Conclusion: Trends indicated improved OS as treatments evolved between 2005 and 2015, but the effect was limited to 1-year OS in stage IV disease.