Together with data on cardiac substructure sensitivities, the knowledge gained from modern cardiac imaging techniques has the potential to ultimately guide RT treatments and post-RT surveillance. Although uniform standardized cardiovascular surveillance recommendations for cancer survivors with cardiac radiation exposure are lacking, modern cardiac imaging allows more sensitive determination of subclinical cardiac dysfunction in the heart, including individual cardiac regions. In addition, an increasing number of studies have examined correlations between radiation doses to specific cardiac regions and cardiac morbidity and mortality ( Central Illustration) ( 3, 5, 9-29). However, data showing correlations between higher heart radiation exposure and cardiac events and survival in patients with lung or esophageal cancer have led to a reexamination of the severe cardiac effects that can occur within the first 2 years after RT ( 5-8). Many studies in patients with breast cancer or lymphoma have demonstrated that radiation-induced cardiac disease (RICD) most often occurs a number of years after RT. Thus, even though advances in RT techniques have decreased incidental cardiac doses, late cardiac toxicity can still develop. Although the heart was originally considered a relatively radiation resistant organ, data examining the association of cardiac radiation dose and adverse outcomes indicate that there can be a ∼4%-16% relative risk of heart disease and major cardiac events per Gray (Gy) of mean heart dose (MHD) of radiation ( 2-4), with no safe dose identified. However, cardiac radiation exposure can lead to long-term adverse outcomes, including cardiac death. Thoracic malignancies, including lung, esophageal, gastric, and breast cancers, as well as childhood cancers and lymphomas, often include RT in definitive curative treatment regimens. Radiation therapy (RT) is a critical component of treatment for more than one-half of adult patients with cancer ( 1). Future efforts should explore further personalization of radiotherapy to minimize cardiac dysfunction by coupling knowledge derived from enhanced dosimetry to cardiac substructures, post-radiation regional dysfunction seen on advanced cardiac imaging, and more complete cardiac toxicity data. In addition, treatment of ventricular arrhythmias with the use of ablative radiotherapy may inform knowledge of radiation-induced cardiac dysfunction. ![]() Advanced cardiac imaging, cardiovascular risk assessment, and potentially even biomarkers can help guide post-radiotherapy patient care. We also highlight data demonstrating that in some cases radiation doses to specific cardiac substructures correlate with cardiac toxicities and/or survival beyond mean heart dose alone. In this review, we provide an overview of the evolution of radiotherapy techniques in thoracic cancers and associated reductions in cardiac risk. With improvements in cardiac-sparing techniques, radiation-induced cardiac dysfunction has decreased but remains a continued concern. Radiation therapy is an important component of cancer therapy for many malignancies.
0 Comments
Leave a Reply. |