Cardiac Monitoring for Thoracic Radiotherapy: Survey of Practice Patterns in the United States

Abstract

American Society of Clinical Oncology (ASCO)'s 2017 Guideline on Prevention and Monitoring of Cardiac Dysfunction in Survivors of Adult Cancers identified patients receiving thoracic radiation (TRT) ≥ 30 Gy (heart in field) at increased risk for developing radiation induced heart disease (RIHD). ASCO encouraged clinicians to actively screen and monitor for baseline modifiable cardiac risk factors and therapy-induced cardiotoxicity in this high-risk population, which would include a majority of lung and esophageal patients obtaining definitive TRT. Further, coronary artery calcium (CAC) is an independent risk factor for adverse cardiac events that can be mitigated with preventative medical therapy. CAC is easily identified on non-contrast thoracic CT simulation scans, yet it is unclear whether ROs are aware of the clinical implications of CAC seen on simulation scans. We sought to assess ROs practice patterns, experiences, and perceptions of cardiac screening and monitoring for TRT patients. A 28-question survey was emailed to United States ROs 3 times from September 2018 to January 2019. Responses were collected on Survey Monkey and descriptive statistics were used to report results. Of the 162 respondents from 42 states, 94% treat non-breast thoracic cancers to doses ≥ 45 Gy with heart in the field, 51% practice in academic settings, and 62% have an average of 1-5 thoracic cancer patients actively on treatment. While 22% have access to a Cardio-Oncology program, 81% were not aware of the ASCO cardiac monitoring guidelines. Only 24% agreed with these guidelines, whereas 41% thought they should be more specific and 35% were not sure. The most significant reported barrier to cardiac monitoring in asymptomatic patients was lack of strong evidence for type and timing of cardiac monitoring tests (69%). The majority (56%) did not monitor cardiac changes after RT. When monitoring, 38% prefer ECHO, yet 72% were unsure or had no preference as to which type of ECHO to order. While 62% agreed that RIHD could occur in any section of the heart in the RT field and that the earliest expected time-point that cancer survivors would be symptomatic from RIHD was <2years (27%), 2-5 years (41%) or 5-10 yrs (26%), 72% would NOT reduce tumor coverage and 67% would NOT reduce RT dose in order to minimize RT heart dose since the priority was cancer control. If CAC was evident on CT sim scans, 68% had never thought about what actions to take or did not take any actions, whereas 38% would refer to internist or cardiologist. Only 7% reported having ongoing clinical trials for cardiac monitoring at their centers. This survey highlights a critical gap in knowledge about cardiac monitoring and potentially missed opportunities for preventive medical management in a high risk population that may have competing life-threatening cardiac risks. Future studies focusing on timing and detection of RIHD may elucidate the utility of cardiac monitoring for TRT patients.