A recent study by researchers at the University of Texas MD Anderson Cancer Center entitled “Prospective Exploratory Analysis of Cardiac Biomarkers and Electrocardiogram Abnormalities in Patients Receiving Thoracic Radiation Therapy with High-Dose Heart Exposure”, published in the Journal of Thoracic Oncology, has demonstrated that high-dose radiation exposure to the heart following thoracic radiation therapy (RT) leads to no clinically significant cardiac events, and only small changes in cardiac biomarkers and electrocardiograms were observed.
For many different types of thoracic cancers, radiation therapy is used as a standard of care. However, even though radiation exposure to the heart is avoided, frequently high radiation exposure is inevitable, and its effects are still ill defined.
In this study, the research team assessed three cardiac function biomarkers — brain natriuretic peptide (BNP), troponin-I (TNI), and electrocardiogram (ECG) — in 25 patients who were receiving high-dose conformal radiation therapy for lung cancer, thymoma, esophageal cancer or malignant mesothelioma, with an expected ≥20 GY radiation exposure to the heart.
Biomarker measurements were done before radiation therapy exposure, on the day of the last dose, and 1 to 2 months after finishing the treatment.
The results demonstrated that before radiation therapy, TNI levels were undetected, increasing moderately in 2 patients following treatment, but decreasing at the follow-up measurement.
Changes in BNP were not observed at any analyzed time-point, and twelve patients had some change in ECG readings during different points in therapy. However these were usually resolved, asymptomatic, and did not require management.
“The main objective of this study was to determine if short-term trends could be observed in the acute setting but we are continuing to follow these patients and intend to pool the results of this study with those involving other patients with locally-advanced disease to determine whether further toxicity arises that warrants longer follow-up with these metrics. A more complete clinical analysis should entail follow-up for at least 2 or 3 years and with an increased dose range; such a design presumably would reveal the impact of dose on both acute and late RT-related toxicity and thereby strengthen the associations observed in this analysis of acute effects,” Dr. Daniel Gomez, lead author of this study stated in an International Association for the Study of Lung Cancer (IASLC) news release.