Stereotactic heart ablative radiotherapy (SHARP): a prospective multicentric phase II trial

Cardiac tumors are exceedingly rare with metastatic involvement representing the most frequent form of malignancy within the heart. In patients presenting with inoperable primary or recurrent malignant cardiac sarcomas or cardiac/epicardial/pericardial metastases, stereotactic body radiotherapy (SBRT) serves as an alternative local treatment to surgery or may, in some cases, constitute the sole viable local treatment modality. To date, there are only case reports or small retrospective studies assessing SBRT dose and toxicity for cardiac SBRT. The goal of this prospective multicentric observational study is to systematically evaluate the feasibility, toxicity and outcome of magnetic resonance-guided stereotactic body radiation therapy (MRgSBRT) in the management of primary and secondary cardiac malignancies.

The treatment is performed using MR-guided SBRT in five fractions on non-consecutive days (6-8 Gy per fraction prescribed to the 80% isodose). Four study centers participate in this prospective phase II trial (Heidelberg, Munich, Rome, Zurich). Eligible patients who consent to participate in the study will undergo treatment as indicated and approved by an interdisciplinary tumor board. Primary objective is to assess the feasibility and safety of online adaptive MRgSBRT; secondary endpoints are local control and survival outcome, acute and late toxicity, patient-reported outcome as well as technical feasibility of treatment.

The findings from this study may serve as a foundation for the future integration of cardiac SBRT into clinical practice guidelines for the management of cardiac malignancies.