Safety of heart radiotherapy for malignant cardiac tumors: a short and long term study

Abstract

Abstract Background Radiotherapy (RT) may be used as a complementary or palliative treatment for selected cases of malignant cardiac tumors, and improves the overall and relapse-free survival in cardiac sarcomas (1–3). Its use is limited by the risk of radiation injury on the cardiac structures (4). Only few data about the safety of cardiac RT are available. Purpose This study aimed to assess the short and long term adverse cardiac effects in a cohort of patients with cardiac malignancies treated with RT directly on the heart. Methods We reviewed the clinical and echocardiographic data of 25 patients (pts) treated with cardiac RT from 2002 to 2021, using Intensity Modulated RT or Tomotherapy at doses of 25–59 Gy over 5–25 fractions for primary or metastatic tumors (21 sarcomas). The patients had ECG and echocardiogram (ECHO) before RT and weekly during the treatment. After RT, the cardiac surveillance included a visit with ECG and ECHO every 3 months for the first 2 years, every 6 months for 3 years, and yearly thereafter. We compared the left ventricular ejection fraction (LVEF) before RT and at the last available follow-up for all patients; for 12 pts whose radiation field included the right chambers, we analyzed also the right ventricular shortening fraction (RVSF) at the last available follow-up. Results The pts were 14 males, 11 females, aged 22 to 75 (median 54) when treated. The intent was adiuvant after R1 surgery in 12 pts, preoperative in 3, palliative or curative for metastatic or unresectable tumors or in patients refusing redo surgery or chemotherapy (10 pts). Anthracyclines chemotherapy was used in 19 pts. The radiation field included the left atrium and/or ventricle in 11 pts, the right heart in 9, both left and right structures in 3. Two pts were lost to follow-up after 36 and 50 months; 17 died, 3 to 175 months after RT (median 12), all for non-cardiac causes; 6 are alive (with complete local remission) 15 to 126 months (median 79) after completing RT. Acute toxicities were: atrial fibrillation in 2 pts, pericarditis in 2 (both reverted in one week with medical therapy) and temporary worsening of ventricular arrhythmias in one pt with myocardial metastases. At last follow-up no significant valvular or pericardial disease was evident; the LVEF was >50% in all pts (5–10% decreased -compared to baseline- in 2 pts, improved in 3, stable in the others) and the RVSF was >35%. Conclusions In our experience, RT may be used in the treatment of cardiac malignancies with little adverse effects both on short term and at a median follow-up of 13 months (and lasting up to >10 years). Funding Acknowledgement Type of funding sources: None.