Epidemiology and prognosis of malignant peripheral nerve sheath tumor (MPNST) in Japan: A population-based analysis using the national cancer registry.

Abstract

The national epidemiology of malignant peripheral nerve sheath tumor (MPNST) remains underexplored. We analyzed Japanese domestic statistics for MPNST using the National Cancer Registry (NCR), a population-based database launched in 2016. We analyzed 837 MPNST cases diagnosed between 2016 and 2019, comparing them with 22,685 non-MPNST soft tissue sarcomas. We assessed demographics, treatment, and survival using Kaplan-Meier and Cox proportional hazards models. The age-adjusted incidence of MPNST in Japan was 0.13 per 100,000. Unlike other sarcomas, MPNST showed a balanced sex ratio and a relatively higher proportion of adolescent and young adult (AYA) patients (18.5 % vs. 10.7 %, p < 0.001). Most MPNSTs (87.4 %) originated from the skin and soft tissues. The 3-year survival rate for MPNST patients (53.0 %) was lower than that for other sarcomas (64.3 %, p < 0.001). Surgery was associated with longer survival (hazard ratio [HR]: 2.09; p < 0.001), while no clear benefit was observed for chemotherapy or radiotherapy. Radiotherapy was more frequently used in MPNST patients (21.1 % vs. 15.6 %, p < 0.001), likely reflecting a selection bias towards non-surgical cases. This is the first study to analyze the national epidemiology and prognosis of MPNST in a socio-economically homogeneous, single ethnic group. MPNST primarily affected the skin and soft tissues, with a higher incidence in the AYA group. Surgery was associated with better outcomes, whereas chemotherapy and radiotherapy implied poorer prognosis owing to selection bias for unresectable cases. The NCR provides a valuable model for research on rare diseases in homogeneous populations.