Safety and Efficacy of Unresectable Malignant Cardiac Tumors Treated with Concurrent Chemoradiation Therapy Using a 1.5T MR-Linac (GASTO-1078).

PURPOSE

This trial aimed to investigate the safety and efficacy of treating malignant cardiac tumors with hypofractionated radiation therapy and concurrent chemotherapy (hypo-CCRT) using a 1.5T MR-Linac.

METHODS AND MATERIAL

Patients with both primary and secondary malignant cardiac tumors underwent split-course hypo-CCRT on a 1.5T MR-Linac, receiving 30 Gy/6 fractions initially, followed by a boost course of 20 to 30 Gy/4 to 6 fractions, totaling 50 to 60 Gy. Concurrent chemotherapy (docetaxel and nedaplatin) was administered weekly. The primary endpoint was local recurrence-free survival (LRFS). Secondary endpoints included objective response rate, progression-free survival (PFS), overall survival (OS), toxicity, and quality of life.

RESULTS

From October 2021 to October 2023, 7 patients were enrolled in the study and received split-course hypo-CCRT on the 1.5T MR-Linac. The median follow-up was 26 months (range, 8.3-36.3 months). The objective response rate was 85.7% (6/7). The 2-year LRFS rate was 71.4%, with the median LRFS not reached. The 2-year PFS rate was 38.1%, with a median PFS of 20.1 months (95% CI, 8.8-31.5 months). The 2-year OS rate was 71.4%, with the median OS yet to be determined. No patients experienced acute or late toxicity above grade 2. Three months posttreatment, the ejection fraction percentage increased from 63.43% ± 7.21% to 68.57% ± 4.28% (P = .02), and the internal diameter of the right ventricle decreased from 24.43 ± 2.99 to 18.86 ± 3.13 mm (P < .01). The European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 scores were significantly improved at 6 months posttreatment (P < .05).

CONCLUSIONS

Split-course hypo-CCRT on MR-Linac for malignant cardiac tumors was feasible, generally well-tolerated, and showed promising oncologic as well as patient-reported outcomes in this small prospective cohort. Further study is warranted for the long-term effects.