A nationwide survey of medical resource usage for cancer treatment using Japanese health claims data from 2011 to 2022.

Multidisciplinary cancer treatments have advanced significantly, especially with molecular targeted therapies improving prognosis. Although these are expensive, their cost impact remains unverified. This study aimed to investigate the overall utilization of healthcare resources and identify the cost drivers of cancer treatment in Japan. In this retrospective cohort study, patients diagnosed with malignancies between April 2011 and March 2022 were classified by cancer type, and monthly insurance claims and applicable medications were analyzed. Breast cancer was the most common, followed by stomach and colon cancers. Cost analysis by cancer type revealed that lung cancer was the most expensive overall, whereas multiple myeloma was the most expensive per person-month. When antineoplastic drug costs were aggregated by mechanism, a rapid increase was observed in the immune checkpoint inhibitor category. Since the advent of immune checkpoint inhibitors, the number of insurance claims for antineoplastic drugs in Japan has increased. Japan's public healthcare system has seen an increase in the cost of cancer treatment at a rate exceeding national economic growth. These findings highlight the need for policies that address the cost-effectiveness and sustainability of cancer care to ensure continued access to high-quality treatment within publicly funded systems in Japan and globally.