# Changing trends in gamma knife surgery to linear accelerator brain stereotactic radiotherapy in Japan: a survey based on the nationwide claims database

## TL;DR

This study shows a shift in Japan from gamma knife surgery to linear accelerator-based brain radiotherapy, with an increase in outpatient treatments.

## Contribution

The study provides new insights into the changing trends of brain stereotactic radiotherapy platforms in Japan using nationwide claims data.

## Key findings

- Gamma knife surgery cases decreased while linear accelerator cases increased significantly from 2014 to 2021.
- The proportion of outpatient treatments rose for both platforms, with over half of linear accelerator cases being outpatient by 2021.
- The total number of stereotactic radiotherapy cases increased by 19.1% over the study period.

## Abstract

This study evaluated the trends in the platform for stereotactic radiotherapy to the brain (SRT), utilizing the open data of the National Database published by the Ministry of Health, Labour, and Welfare.

This study analyzed data from FY2014 to FY2021. The practices included in the study were gamma knife surgery (GKS) and SRT with a linear accelerator (LINAC). The total number of outpatient and inpatient cases in each SRT system was evaluated annually.

From April 2014 to March 2022, the study included 212,016 cases (102,691 GKS and 109,325 LINAC) of the registered 1,996,540 radiotherapy cases. In the first year, 13,117 (54.1%) cases were GKS, and 11,128 (45.9%) were LINAC; after that, GKS decreased, and LINAC increased, reaching the same rate in FY2017. Compared to the first year, the final year showed 11,702 GKS (− 1415 or − 10.8%) and 17,169 LINAC (+ 6041 or + 54.3%), with an increase of 4626 total SRT cases to 28,871 (+ 19.1%). The percentage of outpatient treatment also increased from 4.6 to 11.8% for GKS and from 44.7 to 57.9% for LINAC.

The study found a gradual decrease in the selection of GKS, an increasing trend in the selection of LINAC, and an increase in the overall number of stereotactic irradiations. In particular, the proportion of outpatient treatment increased, indicating that more than half of LINAC was selected for outpatient treatment.

The online version contains supplementary material available at 10.1007/s11604-023-01511-1.