Proton Therapy in the Treatment of Liver Metastases

Local control of hepatic metastases appears to be a major determinant of overall survival. However, many patients are not suitable for resection due to medical or surgical reasons. Therefore, there is an important role for a treatment that can provide the equivalent of tumor resection with minimal morbidity. Stereotactic body radiotherapy (SBRT) delivers an ablative regimen of highly focused external beam radiotherapy that targets one or more discrete extracranial lesions. Published reports using SBRT to treat liver metastases have shown actuarial local control rates ranging from 50-100% with higher doses associated with better local control. In patients with metastatic liver disease, aggressive local therapy using modern radiotherapy techniques are promising and project to have a substantial role in the treatment of metastatic liver cancer to treat unresectable disease. The dosimetric advantage of proton therapy may lead to improved clinical outcomes with less morbidity, however, there is no clinical data to confirm this assertion. We thus propose a phase I study to determine the feasibility and safety of stereotactic body proton therapy in patients with liver metastases followed by a phase II study to determine the efficacy of such treatment on local control.