Clinical Characteristics and Incidences of Benign and Malignant Insulinoma Using a National Inpatient Database in Japan.

Abstract

Insulinoma is the most common pancreatic functional neuroendocrine neoplasm, yet little information on recent clinical practice in patients with insulinoma, especially malignant insulinoma, is available. This work aims to clarify the characteristics and practice patterns in patients with insulinoma using a national inpatient database. Using the Japanese Diagnosis Procedure Combination database, we retrospectively identified patients with insulinoma admitted between 2010 and 2018. We compared background characteristics and therapeutic interventions between patients with benign and malignant insulinoma. We also estimated the incidence of insulinoma using the number of patients with newly diagnosed insulinoma in 2012. We identified 844 patients with benign insulinoma and 102 patients with malignant insulinoma. Patients with malignant insulinoma were younger (median, 55.5 vs 66.0 years, P < .001) and less likely to be female (55.9% vs 65.3%, P = .061) than patients with benign insulinoma. Analysis of therapeutic interventions revealed that patients with malignant insulinoma more frequently received medications (71.6% vs 49.6%, P < .001) but less frequently underwent pancreatic surgery (57.8% vs 72.0%, P = .003). Older patients were a smaller proportion of those undergoing surgery and a larger proportion of those managed with medications without surgery (P < .001). The incidence of insulinoma was estimated to be 3.27 (95% CI, 2.93-3.61) individuals per million Japanese adult population per year. The present study using a nationwide database had a larger sample size than previous studies and revealed definitive differences in patient characteristics and therapeutic patterns between benign and malignant insulinoma.