# Precision Treatment of Pulmonary Sarcoma Metastasis Using Personalized Ultrafractionated Stereotactic Adaptive Radiotherapy: A Case Report

## TL;DR

A personalized ultrafractionated radiotherapy approach successfully treated complex lung metastases in a sarcoma patient with minimal side effects.

## Contribution

A novel adaptive radiotherapy method is demonstrated for treating complex pulmonary sarcoma metastases.

## Key findings

- The PULSAR approach achieved excellent local control with minimal toxicity.
- Tumor regression allowed treatment of a second lesion after lung re-expansion.
- Real-time imaging enabled adaptive treatment planning based on tumor changes.

## Abstract

The lungs represent the most common sites of distant metastases in soft tissue sarcoma (STS) patients. The relative radioresistance of STS renders them ideal targets for stereotactic radiotherapy (SRT). In this study, the treatment of a complex STS lung metastases case involving complete main bronchus occlusion and lung collapse using an image-guided, personalized ultrafractionated stereotactic adaptive radiotherapy (PULSAR) approach is reported. A biologically effective dose (BED) of 102 Gy10 was delivered in two stages separated by 21 days using the CyberKnifeTM platform (Accuray Inc., Sunnyvale, CA, USA) and the Synchrony Lung Optimized (Synchrony-LOTTM) motion management system (Accuray Inc.). Each treatment stage was based on real-time imaging data, allowing for the adaption of the treatment plan to the tumor's size and shape. Prior to the second stage, significant tumor regression was observed, leading to lung re-expansion and restoration of pulmonary function. This expansion enabled the visualization and treatment of a second peripheral lesion, which received a BED of 106 Gy10 in a single session. The applied treatment protocol resulted in excellent local control and minimal toxicity. The combination of the PULSAR approach and real-time imaging techniques hold significant promise for treating complex cases and marks a shift toward more adaptive and personalized radiation oncology.