Initial Treatment Modalities in Patients with Newly Diagnosed Primary Lung Cancer in Japan.

Treatment for lung cancer continues to rapidly evolve. Here, we describe trends in the initial treatment of adults with newly diagnosed primary non-small-cell lung cancer in Japan. This retrospective cohort study used data from JMDC Inc. Claims Database from 2015 to 2023. Adults with lung cancer, confirmed using a combination of diagnosis, treatment, or procedure codes, were enrolled. A total of 9373 patients were included, with a mean age of approximately 59 years. The median time from diagnosis to treatment initiation ranged from 38 days in patients treated surgically to 25 days in patients with distant metastases. The observed trends were a decrease in the percentage of newly diagnosed patients with distant metastases, a decline in chemotherapy use in patients with early-stage disease, and in advanced disease, a more than doubling in the use of targeted therapy, including checkpoint inhibitors, while radiotherapy and chemotherapy tended to decrease. The observed changes in treatment were driven mainly by the increased use of targeted therapies including checkpoint inhibitors and are aligned with current treatment guidelines in Japan. The observation of fewer patients with distant metastases over time possibly indicates earlier detection. Additional research is needed to understand if new therapies are being extended to older and frail patients with lung cancer in Japan.