Nationwide real-world analysis of neuroendocrine tumors in Japan using the JMDC claims database

Nationwide real-world data on neuroendocrine tumors (NETs) remain limited in Japan because of their heterogeneous clinical presentation and indolent disease course. Over the past decade, treatment strategies for NETs have expanded substantially, encompassing somatostatin analogs, molecular targeted agents, cytotoxic chemotherapy, and radioligand therapy. Large-scale administrative claims databases may provide valuable insights into how these evolving therapeutic options are utilized in routine clinical practice. We conducted a retrospective observational study from January 2014 to November 2024 using the Japan Medical Data Center (JMDC) claims database, which contains anonymized health insurance claims from insured individuals across Japan. Patients with NETs were identified using predefined disease codes combined with treatment and procedure records. Patient demographics, primary tumor sites, treatment, including surgery, chemotherapy and radionuclide therapy, and healthcare utilization were analyzed. Overall survival was evaluated using the Kaplan–Meier method. A total of 17,346 patients with NETs were identified. Men accounted for a higher proportion of NET cases than women. Mean age at diagnosis was 63 ± 14 years (63 ± 15 years in women and 64 ± 14 years in men). The annual number of registered NET cases increased steadily throughout the study period. NETs most commonly originated in the digestive tract, particularly the colorectum, followed by the pancreas. Most patients were diagnosed at early stages (Stage I/II). Endoscopic treatment was frequently performed, especially for colorectal NETs. Somatostatin analogs were the most commonly administered systemic agents, and treatment durations were relatively long. The use of nuclear imaging and radionuclide therapy remained limited during the study period. Kaplan–Meier analysis demonstrated that overall survival differed significantly according to tumor stage. Stage IV disease was associated with markedly worse survival compared with Stages I–III (log-rank p < 0.001). In Cox regression analysis, Stage IV was associated with an increased risk of death. JMDC claims data enable feasible identification and characterization of NETs in Japan. This analysis captures the use of diverse treatment modalities, including cytotoxic chemotherapy and radionuclide therapy in Japan. Claims-based analyses provide a useful framework for understanding real-world treatment patterns and the evolving clinical landscape of NETs in Japan.