OBJECTIVES: This study aimed to identify the variation of treatment contents and outcomes and economic burden of lung cancer among the elderly population in Japan. METHODS: New-onset primary lung cancer from April 2013 to March 2019 were identified by using the Kyoto City administrative database for National Health Insurance and Advanced Elderly Medical Service System. Patient characteristics, initial treatment, medical costs, and deaths were analyzed. Continuous variables were calculated using standard descriptive statistical methods. RESULTS: A total of 4845 people who were diagnosed as having lung cancer and received any treatment between 2013 and 2018 were included in the study. The average age of patients was 73 to 74 years for a 6-year study period. The proportion of patients who received surgery, drug therapy, and radiation therapy as initial treatment was 31% to 42%, 36% to 44%, and 21% to 24%, respectively. Healthcare costs increased between fiscal year (FY) 2014 and FY 2018, with a particularly significant increase of 340 million for drug therapy, whereas the mortality rate in <2-year follow-up decreased from 42.7% in FY 2013 to 368% in FY 2016. CONCLUSIONS: This cross-sectional study demonstrated that the improvement in the survival rate and proportion of surgery as an initial treatment was increased whereas drug therapy decreased and medical costs increased among patients with lung cancer over time. Based on these results, it is necessary to implement sustainable healthcare measures with a consideration of cost-effectiveness.