Nationwide trends in mediastinal tumor and myasthenia gravis surgery in Japan: a decade claims-based analysis...

Mediastinal tumor surgery and extended thymectomy for myasthenia gravis (MG) have undergone significant changes with the advancement of minimally invasive techniques. However, nationwide population-based data capturing these trends in Japan remain limited. This study aimed to characterize national surgical trends for mediastinal tumors and MG using a comprehensive administrative claims database.

We analyzed data extracted from the National Database of Health Insurance Claims and Specific Health Checkups (NDB), covering over 95% of insured procedures in Japan. We classified surgeries from 2014 to 2023 by disease category (benign tumor/malignant tumor/MG) and approach (open/thoracoscopic/robotic-assisted). Crude and age-standardized surgery rates were calculated per 100,000 person-years. Temporal trends were assessed using linear and Poisson regression models.

In 2023, a total of 6214 surgeries was performed: 54.4% for benign tumors, 41.6% for malignant tumors, and 4.0% for MG. Thoracoscopic approaches accounted for 76.4% of all procedures (29.4% robotic-assisted), while open surgery comprised 23.6%. Over the decade, age-standardized overall mediastinal tumor surgeries increased significantly (P = 0.0001), driven by marked rises in malignant, thoracoscopic, and robotic-assisted surgeries (each P < 0.0001). In contrast, extended thymectomies and open surgeries declined (P = 0.0019, and < 0.0001, respectively). Age-standardized malignant tumor surgery rates rose in both sexes (relative risk = 1.051 for males, 1.065 for females, and 1.058 overall; P < 0.0001), especially among those aged ≥ 40 years in both sexes (P < 0.0024).

This nationwide study reveals growing surgical demand for mediastinal tumors and underscores the widespread adoption of minimally invasive techniques.