MR-guided stereotactic body radiation therapy for intracardiac and pericardial metastases

Austin J Sim; Russell F Palm; Kirby B DeLozier; Vladimir Feygelman; Kujtim Latifi; Gage Redler; Iman R Washington; Evan J Wuthrick; Stephen A Rosenberg

doi:10.1016/j.ctro.2020.10.006

MR-guided stereotactic body radiation therapy for intracardiac and pericardial metastases

Clin Transl Radiat Oncol. 2020 Oct 31:25:102-106. doi: 10.1016/j.ctro.2020.10.006. eCollection 2020 Nov.

Authors

Austin J Sim¹, Russell F Palm¹, Kirby B DeLozier¹, Vladimir Feygelman¹, Kujtim Latifi¹, Gage Redler¹, Iman R Washington¹, Evan J Wuthrick¹, Stephen A Rosenberg¹

Affiliation

¹ Department of Radiation Oncology, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, United States.

Abstract

Aims: To assess the safety and efficacy of MR-guided stereotactic body radiation therapy (MRgSBRT) for cardiac metastases.

Materials/methods: This single institution retrospective analysis evaluated our experience with MRgSBRT for cardiac metastases. Response rate was compared between pre-RT and post-RT imaging. Symptomatic changes were also tracked and documented.

Results: Between 4/2019 and 3/2020, five patients with cardiac metastases (4 intracardiac and 1 pericardial) were treated with MRgSBRT. Median age at treatment was 73 years (range 64-80) and two patients had pre-existing cardiac disease. Histologies included melanoma and breast adenocarcinoma. Median lesion diameter was 2 cm (range 1.96-5.8 cm). Three patients were symptomatic, one of whom had pulmonary hypertension and RV enlargement. Another patient had an asymptomatic arrythmia. Median PTV prescribed dose was 40 Gy (range 40-50 Gy) and delivered in five fractions on nonconsecutive days. Median PTV volume was 53.4 cc (range 8.7-116.6 cc) and median coverage was 95% (range 84.1-100%). A uniform 3 mm margin was used for real-time gating, allowing a median 7% (range 5-10%) pixel excursion tolerance. Median follow-up was 4.7 months (range 0.9-12.3). Two patients exhibited stable disease, two had a partial response and one exhibited a complete response. All symptomatic patients experienced some relief. There were no acute adverse events, however, one patient without prior cardiac disease developed atrial fibrillation 6 months after treatment. Two patients died of causes unrelated to cardiac MRgSBRT.

Conclusion: In this largest known series of cardiac metastasis MRgSBRT, real-time image guidance enables safe treatment resulting in good response with improving presenting symptoms without acute adverse events.

Keywords: Cardiac metastasis; MR-guidance; Real-time image guidance; SBRT.